Movement of Water.pptx

7/27/2019 Movement of Water.pptx

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Movement of Water

Takes place on three levels:

From soil into cells

From cells into tissues (apoplast andsymplast

From xylem up the stems (bulk flow)


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Movement of Water at the

Tissue/Organ Level

From Cell to Cell, Through the Root to the

Stem

Apoplast

Symplast


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Water Absorption by Roots

Surface is increased by:

Root hairs

Mycorrhizae - 90% of

terrestrial plants Fungus attached to

roots

Hyphae form a

mycelium Hyphae grow into

the root , betweenplants cells


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Most plants form mutually beneficial

relationships with fungi, which facilitate

the absorption of water and minerals

from the soilRoots and fungi form mycorrhizae,

symbiotic structures consisting of plant

roots united with fungal hyphae

2.5 mm

Once soil solution enters the roots

The extensive surface area of cortical cellmembranes enhances uptake of water and

selected minerals


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Water Movement Through Tissues

Symplast pathway through the cytosol of

adjacent cells viaplasmodesmata

Apoplast water movement through the cell

walls

Transmembrane - slow


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Apoplast Symplast

Materials flowing alongthe apoplastic route areblocked by the waxy(suberin) Casparianstrip at the endoderm

Must enter endodermalcells to move into thexylem

Enables endodermalcellsto extract (activetransport)minerals from soil


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Symplast Pathway

Central vacuole stores water/minerals

Tonoplast - membrane

Proton pumps in the

tonoplast, pump H+ into thevacuole

Other active transport

moves soil minerals into

the vacuole (K+

) Makes the cytosol

hyposmotic (increases s )


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Key

Symplast

Apoplast

The symplast is thecontinuum of

cytosol connected

by plasmodesmata.

The apoplast is

the continuum

of cell walls and

extracellular

spaces.

Apoplast

Transmembrane route

Symplastic routeApoplastic route

Symplast

Transport routes between cells. At the tissue level, there are three passages:

the transmembrane, symplastic, and apoplastic routes. Substances may transfer

from one route to another.

(b)

Figure 36.8b


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Figure 36.9

1

2

3

Uptake of soil solution by the

hydrophilic walls of root hairs

provides access to the apoplast.

Water and minerals can then

soak into the cortex along

this matrix of walls.

Minerals and water that cross

the plasma membranes of root

hairs enter the symplast.

As soil solution moves along

the apoplast, some water and

minerals are transported into

the protoplasts of cells of theepidermis and cortex and then

move inward via the symplast.

Within the transverse and radial walls of each endodermal cell is the

Casparian strip, a belt of waxy material (purple band) that blocks the

passage of water and dissolved minerals. Only minerals already in

the symplast or entering that pathway by crossing the plasma

membrane of an endodermal cell can detour around the Casparian

strip and pass into the vascular cylinder.

Endodermal cells and also parenchyma cells within the

vascular cylinder discharge water and minerals into their

walls (apoplast). The xylem vessels transport the water

and minerals upward into the shoot system.

Casparian strip

Pathway along

apoplast

Pathwaythrough

symplast

Plasma

membraneApoplastic

route

Symplastic

route

Root

hair

Epidermis Cortex Endodermis Vascular cylinder

Vessels

(xylem)

Casparian strip

Endodermal cell

4 5

2

1


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Long Distance Transport

Bulk Flow

Movement of Materials From Source to Sink

Roots to LeavesLeaves to Roots


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Root Pressure

Root pressureThe Hydrostastic pressure created between the rootsis known as root pressure.

This root pressure can be demonstrated by cutting the stem of the plant in pot dueto the root pressure in the root the water oozes out of the stem and can bemeasured by inserting a rubber tube with capillary tube with coloured solution anda drop of oil ( to avoid the evaporation ) due to the root pressure the colouredsolution rises up this shows root pressure is present

water pressure that pushes water up the xylem (positive pressure) Root cells pump (active transport) mineral ions into the xylem at night

Lowers water potential in the root

Guttation - exudation of water droplets on the tips of leaf margins More water enters

leaves than istranspired, and theexcess leaks out

Root pressure sometimes results in guttation, (the exudation of waterdroplets on tips of grass blades or the leaf margins of some small, herbaceousdicots in the morning). More water enters the leaves than is transpired, andthe excess is forced out of the leaf.


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Ascent of Sap

The water that enters the root cells is a solution

of numerous and different types of soil inorganic

salts and this aqueous cellular solution is called

Sap

Ascent of sap is the upward movement of the sap

from the roots to the leaves and growing points oapical meristems and other aerial plant parts

Water absorbed by root hairs, enter root

cortex,endodermis, the xylem vessels and

tracheids,then to mesophyll cells of the leaf.

Composition of Xylem sap: It is dilute aqueous

solution with pH 5

It has organic acids, amino acids, and amides

It has plant hormones like abscisic acid and

cytokinins

Xylem

sap

Waterpotentialgradient

Mesophyll

cells

Stoma

Water

molecule

Atmosphere

Transpiration

Xylem

cellsAdhesion Cell

wall

Cohesion,

by

hydrogen

bonding

Water

molecule

Root

hair

Soil

particle

Water

Cohesion

and adhesion

in the xylem

Water uptake

from soil


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Mechanism of Ascent of Sap

Plants lose an enormous amount of

water through transpiration and the

transpired water must be replaced by

water transported up from the roots

Xylem sap rises to heights of more than

100 m in the tallest plants


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Transpiration

Transpiration is the evaporate loss of water by plants

Defination: Loss of water in the vapour form from anypart of the plant body. The heat energy to convertliquid water into vapour is provided by solar energy of

sunlight Types of Transpiration:

A) Foliar or stomatal : Lossof water from tiny pores inleaf called stomata

B) Lenticular : The loss of water from lenticels which ispresent in stem

C) Cuticular : The loss of water from cork of cuticle(where cuticle impermeable membrane)


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Water is drawnup the xylem inthe stem by

three factors:

Root pressure

Capillary action Transpirationpull


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Root pressure refers to the forces that drawswater up to the xylem vessels by osmosis andactive transport.

Capillary action plays a part in upwardmovement of water in small plants.

Transpiration pull refers to the strongest forcethat causes water to rise up to the leaves oftall trees. It is a result of loss of water vapourfrom the leaves (transpiration).


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Transpiration Pull Theory

Water is moved up from the roots ofthe plants, up the stem and out theleaves by the Transpiration-PullTheory (Cohesion-Tension pulltheory).Proposed by Dixon and Joly1895. This theory is applied fromsmall herbs to tall trees

The theory is based on the three keyproperties of water:

1) Cohesion: the ability of watermolecules to stick together

Molecules of water have tremendousforce of attraction to one another

2) Adhesion: the ability of watermolecules to stick to the sides ofhollow tubes. It s attraction tochemicals of different types

3) The surface tension of water


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Plants have continuous xylem vesselsextending from roots to the top of the plants

One end of xylem tube is connected with root

hair via, endodermis and cortex and other end

is connected with sub stomatal cavity via

mesophyll cells . These xylem vessels are

completely filled with water

The water is filled in xylem due to cohesionand adhesion forces of water .The water

column cannot be broken or pulled away from

xylem walls because of cohesion and adhesion

Transpiration results in loss of water from

mesophyll cells hence osmotic pressure

increased so water potential becomes

negative

Xylem vessels of leaves have high water

potential .so water is drawn from the xylem

vessels into mesophyll cells

In other words transpiration develops

transpiration pull on water column


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Experiment to demonstrate the existence of transpiration pull

Mechanism of Transpiration : Mesophyll are arranged loosely with intracellular

spaces and mesophyll loose water continuously and

cell becomes wet and intracellular space is filled withwater and squeezes out through stomata

During Day time:starch (insoluble in water) is converted into glucose

The guard cells are turgid ,they swell up and dorsal

wall of guard cells stretch apart and leads to opening

of ventral walls

This enables water vapors generated in mesophyll

cells to come out in atmosphere

During Night time Glucose again converted into starch and water

Turgor pressure of guard cells decreases since they

loose water to neighboring cells

Hence the ventral walls comes one another ,stomata

closes


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Stomata help regulate the rate of

transpiration Loss of water vapour in

transpiration ,exchange ofoxygen and carbon di oxidein the leaf also occursthrough pores calledstomata

Stomata open in the daytime and closes in nighttime this leads to change inthe turgidity in the guardcells

About 90% of the water aplant loses Escapes through stomata

20

Figure 36.14


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Cells flaccid/Stoma closedCells turgid/Stoma open

Radially oriented

cellulose microfibrils

Cell

wall

Vacuole

Guard cell

Figure 36.15a


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Factors affecting rate of transpiration:

a) Humidity of the air

b) Temperature of the air

c) Strong wind

d) Light


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Mineral Ion Uptake

Roots uptake mineral ions through a process called activetransport.

Active transport requires energy. In the form of ATP

Energy comes from the high number of mitochondria found

in the root hair cells. Minerals are present in the soil as charged particles ( ions)

which cannot move across cell membranes

The concentration of minerals in the soil is usually lowerthan the concentration of minerals in the root

Ions are absorbed from the soil both passive and activetransport.

The endodermal cells have many transport proteinsembedded in their plasma membrane


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Phloem Transport : Flow from source

to Sink Organic nutrients are translocated through the phloem (translocation is

the transport of organic nutrients in the plant)

Phloem sap

Is an aqueous solution that is mostly sucrose

Phloem sap has 15-30% of dissolved solutes ,pH 7.2-8.5 90% is the disaccharide sugars (cane sugar CHO) ,it also contains

amino acids, hormones ,vitamins ,inorganic substance like potassium

ions

Travels from a sugar source to a sugar sink

A sugar source is a plant organ that is a net producer of sugar, such asmature leaves

A sugar sink is an organ that is a net consumer or storage of sugar,

such as a tuber or bulb


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A sugar source Is a plant organ that is a net

producer of sugar, such asmature leaves

A sugar sink

Is an organ that is a netconsumer or storer of sugar,such as a tuber or bulb

Sugar must be loaded intosieve-tube members beforebeing exposed to sinks

In many plant species, sugarmoves by symplastic andapoplastic pathways

Figure 36.17a

Mesophyll cell

Cell walls (apoplast)

Plasma membrane

Plasmodesmata

Companion

(transfer) cell

Sieve-tube

member

Mesophyll cell

Phloem

parenchyma cellBundle-

sheath cell

Sucrose manufactured in

mesophyll cells can

travel via the symplast (blue

arrows) to

sieve-tube members. Insome species, sucrose

exits the symplast (red

arrow) near sieve

tubes and is actively

accumulated from the

apoplast by sieve-tube

members and their

companion cells.

(a)


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The pressure flow or Mass Flow

Hypothesis1. Glucose is created at the leaf (The

Source) during photosynthesis.

Glucose is changed into the

disaccharide sucrose in order to be

transported in the plant.2. This sucrose is actively transported

(uses energy) into the phloem cells in

the leaf.

3. There is a high concentration ofsugar (sucrose) in the phloem at thesource.

4. Because there is so much sugar in

the phloem, some water moves infrom the xylem to try and balance

out the concentration.

5. This creates a high amount of

pressurein the phloem near the

source.


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6. Meanwhile sugar is being actively transported into the root or any otherstorage area in the plant (The Sink).

6. Sinks have lots of sugar (usually joined together to form starch).

7. The phloem cells around a sink have low amounts of sugar and thereforewater will leave them and cause them to have a low amount of pressure


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Due to the difference in pressure in the phloem cells at the Source and the

Sink, sugar will be forced down the phloem along this pressure gradient


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Mineral Nutrition

In 1860,Julius Von Sachs, demonstrated that

plants can be grown to maturity in a defined

nutrient solution in complete absence of

soil . This technique of growing plants in a

nutrient solution is known as Hydroponics

Hydroponics has been successful employedas technique for tomato , seedless cucmber


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Essential nutrient elements There are 17 essential elements in plants.

Absence of any one of the element could prevent plants from

completing its normal life cycle or some essential plantconstituent or metabolite will not be manufactured.

According to the relative concentrations found in tissue (orthe relative concentrations required in nutrient solution),these 17 elements are classified as macronutrients and

micronutrients (trace elements). Macronutrients are morethan 10 mmole per kilogram of dry weight, micronutrient areless than 10 mmole per kilogram of dry weight.


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Macro nutrients

They are present in plant tissues in large amounts, It includes Carbon,

hydrogen, oxygen , nitrogen, phosphorous, sulphur, potassium, calcium

and magnesium

Micro nutrients: or trace elements ,are needed in very small amounts

,includes iron, magnesium, copper, molybdenum, zinc, boron,chloine and

nickel

Essential elements grouped into 4 groups based on their functions

A) Essential elements as Biomolecules

B) Essential elements as component of energy-related compounds (mg

as chlorophyll ,phosphorous as ATP) C) Essential elements that can activate or inhibit enzymes

D) Essential elements can alter osmotic potential of a cell E.g.: potassium

play important role in opening and closing of stomata


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Mineral Nutrition


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Toxicity of Micro nutrients

All the micro nutrients which are required by plants must be in optimum level fornormal growth

If these micro nutrients increase above the optimum level the toxicity increaseswhich affects plant growth

The increase in optimum level cause been seen through the symptoms of the plantE.g.: When the Mn concentration increase the dark spots appear on the leaf

METABOLISM OF NITROGEN:

Nitrogen is an important component of amino acids, proteins, nucleic acidsand chlorophyll and other pigments ,hormones and vitamins

Molecular nitrogen cannot be consumed by plants ,so this Mol N intoelemental N and then fix N to oxygen is an endergonic reaction needs lot of

energy Nitrogen exists as two nitrogen atoms joined by triple covalent bond (NN)

The process of conversion of nitrogen (N) to ammonia termed as nitrogenfixation


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Sources of Nitrogen : In nature ,lightning and UV radiation provide enough energy to convert nitrogen to

nitrogen oxide ( NO, NO, NO)

Industrial combustions, forest fires, automobile exhausts, and power generatingstations

Decomposition of organic nitrogen of dead plants and animals is called ammonification

Ammonia volatiles and re-enters the atmosphere but most of them is converted intonitrate by soil bacteria

2NH+ 3O------------> 2NO+ 2 H + 2HO ( Ammonia is first fixed to nitrite ( NO) bybacteria Nitrosomonas/ Nitrococcus

2NO + O-------2NO ( Nitrite is further oxidised to nitrate with help of bacteriaNitrobacter -------------- these steps are called nitrification .

These nitrifying bacteria are chemoautotrophs

The nitrate (NO) is absorbed by plants and transported to plants

In leaves it is reduced to form ammonia finally forms amide group of amino acids

Nitrate present in soil is reduced to nitrogen by denitrification ( bacteriapseudomonasand Thiobacillus)


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Biological Nitrogen fixation Only certain prokaryotic species are capable of fixing

nitrogen. Reduction of nitrogen to ammonia by living

organisms is called Biological nitrogen fixation Enzyme nitrogenase which is capable of nitrogen

reduction .Microbes which has this enzyme are calledN - fixers

Nitrogen fixing bacteria are free-living or symbioticE.g.: Aerobic bacteriaAzotobacter ,beijernickia whilerhodospirillum is anaerobic and bacillus are free living

Cyanobacteria likeAnabena and Nostocare also free-

living nitrogen fixers Symbiotic biological nitrogen fixation :

It involves study of legume-bacteria relationshipspecies of rod shaped Rhizobium

The most common association on roots is as nodulesthese are small outgrowths on roots

Microbe Frankia also produces nitrogen-fixing noduleson roots of non-leguminous plants

Rhizobium and Frankia are free living in soil ,butsymbionts can fix atmospheric nitrogen

The pink or reddish nodules is because of leguminoushaemoglobin or leg- haemoglobin

Frankia bacteria fixing nodules

Rhizobium N fixing bacteria


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Nodule formation Nodule formation is multiple reaction

between rhizobium and roots of host cells

Steps involved are : a) When a root hair of a leguminous plant

comes in contact with the bacterium -Rhizobium, it curls or becomes deformed.

b) At the site of curling, the rhizobia(bacteria) invade the root tissue.

c) Some of the bacteria within the roottissue enlarge to become membranebound structures called bacteroids.

d) The plant responds to this invasion byforming an infection thread made up ofplasma membrane that grows inward fromthe infected cell of the host, separating the

infected from the rest of the plant. e) Cell division now sets in, in the infected

tissue leading to nodule formation. Thenodule thus formed establishes a directvascular connection with the host for theexchange of nutrients.


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The nodules contain biochemical components such as Enzyme nitrogenase andleghaemoglobin .

The enzyme nitrogenase is a MO-Fe protein and catalyses the conversion ofatmospheric nitrogen to ammonia

Since enzyme nitrogenase is very sensitive to molecular oxygen it requiresanaerobic condition. To protect this from o ,the nodules contain o scavenger

called leg-haemoglobin ( Interesting abt aerobic and anaerobic condition)

During this process nodule formation nitrogenase require high input of energy ( 8ATP for each NH produced)

Fate of Ammonia:

At physiological p .the ammonia is protonated to form NH (ammonium ) ion,hence NH is used to synthesis amino acids

A) Reductive amination : In this ammonia reacts with -ketoglutaric acid andforms glutamic acid

B) Transamination : Transfer of amino group from one amino acid to keto group ofketo acid ,here asparagine and glutamine are two most important amides formed


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Photosynthesis

This membrane system is responsiblefor synthesis of ATP and NADPH(nicotinamide adenine dinucleotidephosphate.) ( LIGHT REACTIONS)

In stroma , enzymatic reactions

incorporate co into plants leading

to synthesis of sugar--- starch(DARK REACTIONS)

Photosystems: (PS)

A photosystem is a small group ofpigment molecules and proteins that

work togeother for the absorption andtransference of light energy

Thylakoids posses two photosystemsPhotosystem I and Photosystem II


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Photosystem I and Photosystem IIPHOTOSYSTEM -- I PHOTOSYSTEM -- II

It is 85nm in diameter , reaction centeris chlorophyll a pigment molecule called

pigment 700 ( P700) max absorption at

700 nm

It is 110 nm in diameter , reaction centeris chlorophyll a pigment molecule called

pigment 680 (P680) max absorption at

680 nm

It is embedded in stroma thylakoids It is embedded in the grana thylakoids

It is associate with light harvesting

complex I (LHC I), ferredoxin reducing

substance (FRS), ferredoxin (Fd) and

plastocyanin (PC)

It is also associated with light harvesting

complex II (LHC II), Pheophytin,

plastoquinone

It is involved in both cyclic and Non-cyclicphotophosphorylation

This system is involved in only non-cyclicphotophosphorylation

It is not involved in photolysis of H0 and

no evolution of 0

It is involved in photolysis of H0 and

evolution of 0

Mechanism of Photosynthesis


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Mechanism of Photosynthesis Light reactions is 1st phase of

photosynthesis which is light

dependent reaction

Location: Thylakoidmembrane of grana and

stroma thylakoid

It is photochemical reaction

involve conversion of solar

energy into chemical energy

which is available in form of

ATP and NADPH

Light reaction is also known

as HILL REACTION

Light reaction involve :

photolysis of H0

Photophosphorolyation is the

conversion of ADP into ATP

by addition of inorganic

phosphate using light energy

Non-Cyclic


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y

Photophosphorylation

The electrons lost by P680 (PS-II) are taken

up by P700 (PS-I) and do not get back to

P680 i.e., unidirectional and hence it is

called noncyclic phosphorylation.The electrons pass through the primary

acceptor, plastoquinone (PQ), cytochrome

complex, plastocyanin (PC) and finally to

P700.

The electrons given out by P700 are taken

up by primary acceptor and are ultimately

passed on to NADP.The electrons combine with H+ and

reduce NADP to NADPH2. The hydrogen

ions also called protons are made

available by splitting up of water.

Non-cyclic photophosphorylation needs

a constant supply of water molecules.

The net result of non-cyclicphosphorylation is the formation of

oxygen, NADPH and ATP molecules.

Oxygen is produced as a waste product of

photosynthesis.


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Cyclic

PhotophosphorylationThe electrons released by P700 of PS-I in the

presence of light are taken up by the primaryacceptor and are then passed on to ferredoxin(Fd), plastoquinone (PQ), cytochrome complex,plastocyanin (PC) and finally back to P700 i.e.,electrons come back to the same molecule aftercyclic movement

The cyclic photophosphorylation also results inthe formation of ATP molecules just like in non -cyclic photo phosphorylation.

As the electrons move downhill in the electrontransport chain, they lose potential energy andATP molecules are formed in the same way as inmitochondria during respiration.

During cyclic photophosphorylation, electronsfrom photosystem - I are not passed to NADPfrom the electron acceptor. Instead the electronsare transferred back to P700. This downhillmovement of electrons from an electronacceptor to P700 results in the formation of ATP

and this is termed as cyclicphotophosphorylation.

It is very important to note that oxygen andNADPH2 are not formed during cyclephotophosphorylation


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Cyclic Photophosphorylation

It is associated with PSI

The electron expelled from

chlorophyll molecule is cycled

back

Photolysis of water and evolution

of oxygen do not take place

Photophosphorylation takes place

at two places

NADP is not reduced

Noncyclic photophosphorylation

It is associated with both PS I and

PSII

The electrons are not cycled back

but compensated by theelectrons from photolysis of

water

Photolysis of water and evolution

of o takes place

Photophosphorylation takes place

only at one place

NADP is reduced to NADPH


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THE CALVIN CYCLE

The C3 type of carbon reactions occurs in the stroma ofthe chloroplast. It is also called Calvin cycle after itsdiscoverer, Melvin Calvin.

a) In the first step CO2

is accepted by a 5- carbonmolecule, ribulose -1,5 biphosphate (RuBP) and 2molecules of 3-carbon compound that is 3-phosphoglycerate (PGA) are formed. This reactionis catalysed by an enzyme called Rubisco-Ribulosebiphosphate carboxylase oxygenase. Formation ofPGA is called carboxylation.

b) The 3 - carbon compound formed is the first stableproduct of this pathway and hence the name C3pathway.

c) After carboxylation, reduction of PGA occurs byutilizing ATP and NADPH2 formed duringphotochemical reactions. Reduction results in the

formation of glyceraldehyde-3-phosphate.

d) These 3 - carbon molecules, also called triosephosphates are diverted from the Calvin cycle andact as precursors for the synthesis of sucrose andstarch.

The Calvin cycle proceeds in three stages: (1)carboxylation, during which CO2 combines with

ribulose-1,5-bisphosphate (2) reduction, during which

carbohydrate is formed at the expense of the

photochemically made ATP and NADPH; and (3)

regeneration during which the CO2 acceptor ribulose

1,5-bisphosphate is formed again so that the cycle

continuesFor the cycle to continue on its own regeneration of the

initial 5- carbon acceptor molecule i.e., RuBP takes

place, from glyceraldehyde 3- phosphate using an ATP

molecule.


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In C4 plants the photosynthesis takes

place in a chloroplast of a thin-walled

mesophyll cell and a 4-carbon acid is

handed off to a thick-walled bundle

sheath cell where the Calvin cycle

occurs in a chloroplast of that second

cell. This protects the Calvin cycle from

the effects ofphotorespiration.
http://hyperphysics.phy-astr.gsu.edu/hbase/biology/phoc.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/biology/phoc.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/biology/phoc.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/biology/phoc.html


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THE C PATHWAY

The C4 pathway is designed to efficiently fix CO2 at low

concentrations and plants that use this pathway are known as

C4 plants. These plants fix CO2 into a four carbon compound

(C4) called oxaloacetate. This occurs in cells called mesophyll

cells.1. CO2 is fixed to a three-carbon compound called

phosphoenolpyruvate to produce the four-carbon

compound oxaloacetate. The enzyme catalyzing this

reaction, PEP carboxylase, fixes CO2 very efficiently so the

C4 plants don't need to to have their stomata open as

much.

2. The oxaloacetate is then converted to another four-carbon compound called malate in a step requiring the

reducing power of NADPH.

3. The malate then exits the mesophyll cells and enters the

chloroplasts of specialized cells called bundle sheath cells.

Here the four-carbon malate is decarboxylated to produce

CO2, a three-carbon compound called pyruvate, andNADPH. The CO2 combines with ribulose bisphosphate

and goes through the Calvin cycle.

4. The pyruvate re-enters the mesophyll cells, reacts with

ATP, and is converted back to phosphoenolpyruvate, the

starting compound of the C4 cycle.


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.

These C4 plants are well adapted to (and likely to befound in) habitats with high daytime temperatures

intense sunlight.

Some examples: crabgrass

corn (maize) sugarcane

sorghum

Photorespiration

Photorespiration occurs when the CO2 levelsinside a leaf become low. This happens on hot dry days

when a plant is forced to close its stomata to preventexcess water loss. If the plant continues to attempt tofix CO2 when its stomata are closed, the CO2 will getused up and the O2 ratio in the leaf will increaserelative to CO2 concentrations.

When the CO2 levels inside the leaf drop to around 50ppm, Rubisco starts to combine O2 with RuBP instead

of CO2. The net result of this is that instead of producing 2 3C

PGA molecules, only one molecule of PGA is producedand a toxic 2C molecule called phosphoglycolate isproduced.

Oxidation of ribulose-1,5-bisphosphate

by Rubisco produces a 3-carbon

compound, 3-phosphoglycerate, and a

2-carbon compound,

phosphoglycolate. Because carbon is

oxidized, the process is termed

photorespiration .


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C PATHWAY Photosynthesis occurs in

mesophyll cells

The CO molecule acceptor isRuBp

The first stable product is a 3ccompound 3-PGA

Photorespiration rate is highand leads to loss of fixed CO.It decreases CO fixation rate

Optimum temp is 20-25c Examples of C plants are rice ,wheat and potato

C PATHWAY Phtosynthesis occurs in

mesophyll and bundle sheathcells

The CO acceptor molecule is

phosphoenol pyruvate The fist stable product is 4c

compound OAA

Photorespiration is negligibleand it is almost absent hence,it increases CO fixation rate

Optimum temp is 30-45c

Examples of C plants aremaize, sugarcane etc


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Factors affecting Photosynthesis

There are several factors which

affect the rate of photosynthesis as

described below:

A) Light intensity :

The rate of photosynthesis

increases almost linearly with

increase in light intensity

further increase in light intensity,

the rate of photosynthesis starts to

level off and reaches

saturation

Limiting to photosynthesis at

extremely high light intensity,when leaves are unable to utilize

the absorbed light, the rate of

photosynthesis declines by a

phenomenon called photo inhibit!


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B) Carbondi- oxide Photosynthesis occurs at a very wide

range of C02 concentration. At verylow C02 concentration, photosynthesisis strongly limited by the low C02

The increase in C02 concentration, therate of photosynthesis increases

C) Water

The amount of water utilized inphotosynthetic reactions is quitesmall. Therefore, water rarelybecomes a limiting factor for

photosynthesis. If it gets too cold, the rate of

photosynthesis will decrease. Plantscannot photosynthesise if it gets toohot.


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Respiration

Cellular respiration or themechanism of breakdown of

food materials within the cell to

release energy , and the trapping

of this energy for synthesis of

ATP

The breakdown of C-C bonds ofcomplex compounds through

oxidation within the cell ,leading

to release of considerable

amount of energy is called

Respiration


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Glycolysis

Glycolysis literally means "splittingsugars." In glycolysis, glucose (a six

carbon sugar) is split into two

molecules of a three-carbon sugar.

Glycolysis yields two molecules of ATP

(free energy containing molecule), two

molecules of pyruvic acid and two"high energy" electron carrying

molecules of NADH.

Glycolysis can occur with or without

oxygen. In the presence of oxygen,

glycolysis is the first stage ofcellular

respiration.

Without oxygen, glycolysis allows cells

to make small amounts of ATP. This

process is called fermentation.

Fate of glucose in living systems
http://biology.about.com/library/weekly/aa090601a.htmhttp://biology.about.com/library/weekly/aa090601a.htmhttp://biology.about.com/library/weekly/aa090601a.htmhttp://biology.about.com/library/weekly/aa090601a.htm


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Th 10 l d i i l l i Th


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There are 10 enzyme-catalyzed reactions in glycolysis. There are two stages

Stage 1: Reactions 1-5) A

preparatory stage in which

glucose is phosphorylated,converted to fructose which is

again phosphorylated and

cleaved into two molecules of

glyceraldehyde-3-phosphate. In

this phase there is an investment

of two molecules of ATP. Stage 2: (reactions 6-10) The two

molecules of glyceraldehyde-3-

phosphate are converted to

pyruvate with concomitant

generation of four ATP

molecules and two molecules ofNADH. Thus there is a net gain of

two ATP molecules per molecule

of Glucose in glycolysis.


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From one molecule of Glucose:

1Gl+2ATP+2NAD++ 4ADP+ 4Pi = 2pyruvate+2NADH+4ATP+ 2ADP+ 2Pi

After balancing: 1Gl + 2NAD++ 2ADP + 2Pi = 2pyruvate+2ATP + 2NADH

2 molecules of ATP generated can directly be used for doing work or

synthesis. The 2 NADH molecules are oxidized in mitochondria under aerobiccondition and the free energy released is enough to synthesize 6molecules of ATP by oxidative phosphorylation.

Under the aerobic condition, pyruvate is catabolized further in

mitochondria through pyruvate dehydrogenase and cytric acid cycle whereall the carbon atoms are oxidized to CO2. The free energy released is usedin the synthesis of ATP, NADH and FADH2.

Under anaerobic condition: Pyruvate is converted to Lactate in homolacticfermentation or in ethanol in alcohalic fermentation.


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Anaerobic Respiration

If no oxygen is available, cells can obtain energythrough the process ofanaerobic respiration.

A common anaerobic process isfermentation.

Fermentation is not an efficient process and results inthe formation of far fewer ATP molecules than aerobicrespiration.

There are two primary fermentation processes:

1. Lactic Acid Fermentation

2. Alcohol Fermentation


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Lactic acid fermentationoccurs when oxygen

is not available.

For example, in muscle tissues during rapidand vigorous exercise, muscle cells may be

depleted of oxygen. They then switch from

respiration to fermentation.


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The pyruvic acid formed during glycolysis is broken downto lactic acid and energy is released (which is used to formATP).

Glucose Pyruvic acid Lactic acid + energy


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The process oflactic acid fermentation replaces the process of aerobic

respiration so that the cell can have a continual source of energy, even inthe absence of oxygen.

However this shift is only temporary and cells need oxygen for sustainedactivity.

Reactions of the

i i id lClaisen condensation


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citric acid cycle

The citric acid cyclehas eight steps

Claisen condensation

thioester + ketone


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Balance Sheet for the Transition


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Balance Sheet for the TransitionReaction and Krebs Cycle

Input

2 Pyruvate2 ADP + 2 Pi

8 NAD+

2 FAD

Output

6 CO22 ATP

8 NADH

2 FADH2


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1. Formation of citrate


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2. Formation of isocitrate via cis-aconitate


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Iron-sulfur center in aconitase

2. Formation of isocitrate via cis-aconitate


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Iron-sulfur center in aconitase

3. Oxidation of isocitrate to a-ketoglutarate and CO2


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g 2

The NADH produced here is the first link between the TCA cycle

and electron transport and oxidative phosphorylation.

4. Oxidation of a-ketoglutarate to Succinyl-CoA and CO2


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E1a-ketoglutarate dehydrogenase

E2 dihydrolipoyl transsuccinylase

E3 dihydrolipoyl dehydrogenase

5. Conversion of succinyl-CoA to succinate


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6. Oxidation of succinate to fumarate


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Malonate is a strong competitive

inhibitor of succinate dehydrogenase

7. Hydration of fumarate to malate


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8. Oxidation of malate to oxaloacetate


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Products of one turn of the citric acid cycle


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ETS

The metabolic pathway through which the electrons passes from one carrier toanother is called Electron transport system (ETS)

It is present in the inner mitochondrial membrane .

Electrons from NADH produced in mitochondrial matrix during citric acid cycle are

oxidized by an NADH dehydogenase (complex I)

Electrons ------ubiquinone via FADH2 (complex II)-----generated during oxidation ofsuccinate

Reduced ubiquinone (ubiquinol) is oxidised to transfer electron to cytochome c via

cytochrome bc1 (complex III )

Cytochrome c is small protein act as mobile carrier in transfering electrons to

complex IV (cytochrome c oxidase complex) containing cytochrome a and a3

When electrons pas from one carrier to another via complex I to IV ,they are

coupled to ATP synthase (complex V) ------poduction of ATP from ADP and Pi

Finally oxidation of one molecule of NADH -----3 molecules of ATP

Electron Transport Chain:


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1. NADH transfers its

hydrogen's (each

containing a proton and an

electron) to the electron

carrier protein

NADHNADH

H

+

e-

e-



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Coenzyme

Q

e-

e-

H

+

2. Some electron carrier

proteins such as Coenzyme Q

can accept Protons as electrons

are passed through it

This increases the proton

gradient across the membrane

and enhances the proton

motive force



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3. During aerobic respiration,

the last protein transfers a pair

of electrons to an oxygen

molecule to form H20 (the O2

splits first)

e- e-

OO

2 O

molecule

= O2O

One

splits

H

+

H

+

H H

O



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ATP synthase

enzyme

H

+

H

+

H

+

H

+

H

+

H

+

ADP PATP

4. The ATP synthase enzyme utilisesthe proton motive force, and is able

to use energy formed to carry out the

process of phosphorylation from ADP

to ATP

S


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Summary:

Glycolysis:

2x ATP

2x NADH

2x Pyruvate (3C)

Link reaction:

2x Acetyl-CoA

2x NADH

2x CO2

Krebs:

6x NADH

2x FADH22x ATP

4x CO2

Electron transport chain:

All the hydrogen molecules from

the previously made NADH andFADH2 molecules are converted

into ATP. A total of 30 could

potentially be made. However

due to leakiness, it makes around

26/28 ATP.

G h d D l


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Growth and Development

Differentiation : The cells derived from root apical and shoot-apicalmeristems and cambium differentiate and mature to perform specific functions.

During differentiation cells undergo major structural changes both in their cell wall

and in protoplasm

De differentiation: The living differentiated cells that by now have lost thecapacity to divide can regain the capacity of division

Re differentiation : Meristem/ tissues are able to divide and produce cellsthat once again loose the capacity to divide but mature to perform specific

functions

Development : It is a term that includes all changes that an organism goes through during its life

cycle from germination of the seed to senescence


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Growth:Growth can be defined as an irreversible permanent increase insize of an organ or its parts or even of an individual cell.

Generally, growth is accompanied by metabolic processes (both anabolic and

catabolic), that occur at the expense of energy.

Growth can be defined as an irreversible permanent increase in size of anorgan or its parts or even of an individual cell.

Growth Rate:The increased growth per unit time is termed as growth rate. An organism, or a part of the organism can produce more cells in a variety of ways.

The growth rate shows an increase that may be arithmetic or geometrical.

In arithmetic growth, following mitotic cell division, only one daughter cell

continues to divide while the other differentiates and matures.


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Mathematically, it is expressed as

Lt = L0 + rt

Lt= length at time t

L0= length at time zero

r = growth rate / elongation per unit time.

The exponential growth can be expressed as

W1 = W0 ert

W1 = final size (weight, height, number etc.)

W0 = initial size at the beginning of the period

r = growth rate

t = time of growth

e = base of natural logarithms

PLANT GROWTH REGULATORS


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The plant growth regulators (PGRs) are small, simple molecules of diverse chemicalcomposition.

indole compounds (indole-3-acetic acid, IAA);

adenine derivatives (N6-furfurylamino purine, kinetin),

derivatives of carotenoids (abscisic acid, ABA);

terpenes (gibberellic acid, GA3) or gases (ethylene, C2H4). Plant growth regulators are variously described as plant growth substances, plant

hormones phytohormones in literature.

Major Plant Growth Regulators


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j g

Auxins: Auxins (from Greek auxein : to grow) was first isolated from human urine. The term auxin is applied to the indole-3-acetic acid (IAA), and to other natural and synthetic

compounds having certain growth regulating properties. They are generally produced by thegrowing apices of the stems and roots, from where they migrate to the regions of their action.

Auxins like IAA and indole butyric acid (IBA) have been isolated from plants. NAA (naphthaleneacetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic) are synthetic auxins.

They help to initiate rooting in stem cuttings,

In application widely used for plant propagation.

Auxins promote flowering e.g. in pineapples. They help to prevent fruit and leaf drop at early stagesbut promote the abscission of older mature leaves and fruits.

In most higher plants, the growing apical bud inhibits the growth of the lateral (axillary) buds, aphenomenon called apical dominance.

Removal of shoot tips (decapitation) usually results in the growth of lateral buds. It is widely appliedin tea plantations, hedge-making.

Auxins also induce parthenocarpy, e.g., in tomatoes. They are widely used as herbicides. , 4-D,widely used to kill dicotyledonous seeds, does not affect mature monocotyledonous plants.

It is used to prepare seed-free lawns by gardeners. Auxin also controls xylem differentiation andhelps in cell division.


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Gibberellins: Gibberellins are another kind of promotery PGR.

They are denoted as GA1, GA2, GA3 and so on. However, Gibberellic acid (GA3)

was one of the first gibberellins to be discovered and remains the most intensively

studied form. All GAs are acidic.

They produce a wide range of physiological responses in the plants.

Their ability to cause an increase in length of axis is used to increase the length of

grapes stalks.

Gibberellins, cause fruits like apple to elongate and improve its shape. They also

delay senescence. Thus, the fruits can be left on the tree longer so as to extend

the market period. GA3 is used to speed up the malting process in brewing industry.

.


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Cytokinins: Cytokinins have specific effects on cytokinesis, and were discovered as kinetin

(a modified form of adenine, a purine) from the autoclaved herring spermDNA.

Kinetin does not occur naturally in plants. Search for natural substances with

cytokinin-like activities led to the isolation of zeatin from corn-kernels andcoconut milk.

Natural cytokinins are synthesised in regions where rapid cell division occurs,for example, root apices, developing shoot buds, young fruits etc. It helps toproduce new leaves, chloroplasts in leaves, lateral shoot growth andadventitious shoot formation.

Cytokinins help overcome the apical dominance. They promote nutrient mobilisation which helps in the delay of leaf

senescence.


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Ethylene: Ethylene is a simple gaseous PGR. It is synthesized in large amounts by tissues

undergoing senescence and ripening fruits.

Influences of ethylene on plants include horizontal growth of seedlings,swelling of the axis and apical hook formation in dicot seedlings.

Ethylene promotes senescence and abscission of plant organs especially of

leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate

during ripening of the fruits. This rise in rate of respiration is called respiratoryclimactic.

Ethylene breaks seed and bud dormancy, initiates germination in peanutseeds, sprouting of potato tubers. Ethylene promotes rapid internode/petiole

elongation in deep water rice plants. It helps leaves/ upper parts of the shoot to remain above water. Ethylene also

promotes root growth and root hair formation, thus helping the plants toincrease their absorption surface.


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Abscisic Acid:It acts as a general plant growth inhibitor and an inhibitorof plant metabolism.

ABA inhibits seed germination. ABA stimulates the closure of stomata in the

epidermis and increases the tolerance of plants to various kinds of stresses.

Therefore, it is also called the stress hormone.

ABA plays an important role in seed development, maturation and dormancy.

By inducing dormancy, ABA helps seeds to withstand desiccation and other factors

unfavorable for growth. In most situations, ABA acts as an antagonist to GAs.


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Photoperiodism: Flowering in certain plants depends not only on a combination of light and dark

exposures but also their relative durations. This response of plants to periods of

day/night is termed photoperiodism. .

It has been hypothesized that there is a hormonal substance(s) that is responsible

for flowering. This hormonal substance migrates from leaves to shoot apices for

inducing flowering only when the plants are exposed to the necessary inductive

photoperiod.

The significance of photoperiodism is in regulating flowering in plants. Flowering is

an important step towards seed formation and seeds are responsible for

continuing the generation of a plant. So, photoperiodism has an important role to

play in evolution.


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Vernalisation: There are plants for which flowering is either quantitatively or qualitatively

dependent on exposure to low temperature. This phenomenon is termedvernalisation.

It prevents precocious reproductive development late in the growing season,and enables the plant to have sufficient time to reach maturity.

Vernalisation refers specially to the promotion of flowering by a period of lowtemperature.

Some important food plants, wheat, barley, rye have two kinds of varieties:winter and spring varieties. The spring variety are normally planted in thespring and come to flower and produce grain before the end of the growingseason. Winter varieties, however, if planted in spring would normally fail to

flower or produce mature grain within a span of a flowering season. Hence,they are planted in autumn. They germinate, and over winter come out assmall seedlings, resume growth in the spring, and are harvested usually

around mid-summer.

BIOMOLECULES


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BIOMOLECULES1. Molecules containing Carbon, Hydrogen, Nitrogen, and

often Oxygen.

2. They make up living organisms

3. Examples: Methane (CH4) Glucose (C6H12O6) are allorganic molecules

4. Basic Molecule: Proteins, Carbohydrates (sugars), Lipids(Fats), Nucleic Acid (DNA, RNA)

5. Macromolecule: Large molecules of the above that canbe broken down.

Ex. Starch into sugar

Protein Basics


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Protein Basics Made of Amino Acid Chains

Amino Acids are bondedthrough a peptide bond

3 main parts

- Amino group NH2- Carboxyl group COOH

- R group (side chain)each of the 20 types

of amino acids have

a unique R group


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Protein Shapes


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Protein Shapes

A proteins shape is determined by the orderthat amino acids are joined in

The shape of a protein determines its function

Hemoglobin antibody enzymes polymerase

Protein Structure


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Four Levels of Structure allow for any shape

2-28

Protein Structure


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Protein Structure Primary Structure

Primary structure is the order of the amino acids thatmake up a protein.

- the interactions of the R groups on each amino acid

cause the molecule to bend and fold different

arrangements create different shapes- as a result- the order of

amino acids determines

the shape of the protein

- shape determines function- changing a single amino acid can change a proteins

shape.

Protein Structure Secondary Structure


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Protein Structure- Secondary Structure

The folding proteins often assume one of twogeneral shapes

pleated sheets or an alpha helix these are the

proteins secondary structure.

- hydrogen bonds between amino acids

stabilize the secondary structureAlpha Helix


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Protein Structure Tertiary Structure

The coiled or pleated structures continue to fold untilthey form a complex three dimensional structure.

- most proteins are completed at this stage and arefully functioning proteins.

Remember: Shape determines function

Protein Shape Quaternary Structure


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Protein Shape-Quaternary Structure

Some more complex proteins are assembledfrom two

or more protein molecules.

- Insulin 2 forms 2 proteins or 6 proteins

- Hemoglobin 4 proteins

Protein Functions


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Proteins are the Worker Molecules of Living Things

Enzymes - proteins that allow chemical reactions tooccur in living things

Antibodies proteins that protect the body frominfection

Structure cytoskeleton, hair, nails, muscles, spiderweb, silk, feathers ,horns, hooves etc.

Hormones chemical messengers

Cell membrane proteins can act as channels throughthe cell membrane

- receptor proteins found on membranetransmit signals to the inside of cells

Hemoglobin protein found in blood that carries oxygen

Nucleic Acid Basics


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Nucleic Acid Basics

Made of C,H,O,N,P SPONCH

Monomer is a nucleotide

Functions

- information storage- information transfer

- energy transfer

Meet the Monomer-Nucleotide


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Meet the Monomer-Nucleotide

P = Phosphate GroupS= 5 Carbon Sugar (ribose or deoxyribose)B= Nitrogen Base

Meet the Polymer


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Meet the Polymer

Polymers of nucleic acids are chains ofnucleotides joined by condensation reactions

They are held together by covalent bonds

between the sugar of one nucleotide and thephosphate of another

- called phosphodiesterbonds

Meet the Polymers


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Meet the Polymers

DNA 2 chains of

nucleotides held RNA

together by H Bonds


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Nucleic Acid Types-DNA

Deoxyribonucleic Acid

made of two strands ofnucleotides

Form a double helix DNA stores hereditary

information

- recipes for theproteins

found in the cellsnucleus


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Nucleic Acid Types- RNA

Ribonucleic Acid

Single strand of nucleotides

forms a single helix

transfers information from

the DNA to the ribosomes

- carries a protein recipe to

the ribosome

-ribosomes are structures in a cellthat make protein

DNA- stores protein recipes in the nucleus

f


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RNA transfers them to the ribosome to be built

DNA RNA


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DNA vs. RNA

Double stranded Single Stranded

SugarDeoxyribose Sugar ribose

Nitrogen Bases Nitrogen Bases

Adenine Adenine

Thymine Uracil

Guanine Guanine

Cytosine Cytosine


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Nucleic Acid Types - ATP

Adenosine Tri-Phosphate

ATP is a single nucleotide

high energy molecule

produced by cellular

respiration

transfers energy within

cells

Li id B i


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Lipid Basics

Made of C,H,O

monomer = glycerol + fatty acids

hydrophobic - dont dissolve in water

oil and water dont mix

Fatty Acids


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Fatty Acids

2 typessaturated and unsaturated

- Whats the difference?

- saturated fatty acids contain

no double bonds

between C atoms

- holds the maximum # of H atoms

- unsaturated fatty acids

contain double bonds

between C atoms atoms


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Lipids- Fats and Oilsenergy insulation

and moreFats & Oils (triglycerides)- long term energy

storageFat has twice the calories of carbohydrates.

fat = 9 cal/g sugar= 4 cal/g

Lipids have more C H bonds which store energy

2-24

Health tip:

Saturated or

hydrogenated

fats(bad) vs.

unsaturated

(good)

Li id t d f ti


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Lipids: types and functions

Fats/Oils long term energy storage,

insulation and protection

Phospholipids cell membranes

Steroids make hormones (chemical

messengers)

Waxes waterproofing

Fats


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Fats

Solid at room temperature

Energy storage in animals

contain saturated fatty acids

Saturated fat and fatty acid

Stearic acid

Oils


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Oils

energy storage in plants

contain unsaturated fatty acids

liquid at room temperature

Unsaturated fat and fatty acidDouble bondcauses moleculeto bend

Oleic acid

Ph h li id


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Phospholipids-

Glycerol

only 2 fatty acids (not 3 like fats and oils)

3rd fatty acid is replaced by a

phosphate moleculeSPONCH

Phospholipid structure


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Phosphate molecule forms a hydrophilic (water

loving) head Fatty acid molecules make up a hydrophobic

tails

CH2OPO OO

CH2CH

CH2

OO

C O C O

Phosphate

Glycerol

(a) Structural formula (b) Space-filling model

Fatty acids

(c) Phospholipidsymbol

Hydrophobictails

Hydrophilichead

Hydrophobictails

Hydrophilich

ead

CH

2 Choline

+

Figure 5.13

N(CH3)

3

myelin - phospholipid that insulates nerve


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myelin phospholipid that insulates nerve

cells

We are all literally Fatheads


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Lipids- Cholesterol

connected rings of carbon component of cell membrane adds to the integrity of

the membrane

used to make steroids

Steroids: Lipids that act as Hormones


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Steroids: Lipids that act as Hormones

Hormonesare chemical messengers- produced in one part of the body, they travel to and

cause changes in another part of the body

- Hormones control:growth

developmenttissue function

sexual function

the way our bodies use food,

the reaction of our bodies to emergencies,

mood

- examples

estrogens

testosterone

Estrogen Testosterone

Waxes-Lipids that repel water


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p p

- found on the surface of leaves

- found on animal hair to keep it pliable

- found on the feathers of water birds to

prevent them from becoming waterlogged

Carbohydrates-sugars


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y g

Made of C, H,O

Carb = Carbon hydr = water Carbohydrate = carbon +water

general formula = CH2O 2-1 ratio of hydrogen tooxygen like water H2O

ribose C5H10O5

glucose C6H12O6sucrose C12H22O11

many carbohydrate names end in -ose

More carbohydrate basics


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y

Monomer: monosaccharide one sugar Functions of carbohydrates:

Energy for metabolism (glucose)

Short term energy storage (glycogen/starch)

Structure: plants cell wall animals

exoskeleton

Source of carbon for other molecules Cell surface markers cell identification

Monosaccharide: Simple Sugars


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p g

Monossaccharides like glucose are the main

source of energy in living things

Disaccharides-2 sugars


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g

2 monosaccharides linked together by acondensation reaction

- form a glycosidic bond

Examples:

Sucrose Table Sugar

glucose + fructose

Lactose Milk Sugar

glucose + galactose

Maltose

glucose + glucose

Polysaccharides-Many Sugars


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y y g

Polysaccharides are polymers composed of largenumbers of monosaccharides.

- the monosaccharides are joined bycondensation reactions.

- form glycosidic bonds

Used for short term

energy storage and

structure

Energy Storage Polysaccharides


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gy g y

Starch

polymer made

up of glucose

monomers

Stores glucose

in plants

Chloroplast Starch

1 m

Starch: a plant polysaccharide

Glycogen


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Polymer of glucose monomers

Is the major storage form of glucose in animals

Stored in liver and muscle

More highly branched than

starch contains more

stored energy

Mitochondria Glycogengranules

0.5 m

Glycogen: an animal polysaccharide

Glycogen

Structural Polysaccharides


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Structural Polysaccharides

Cellulose Is a polymer of glucose connected in a

straight unbranched chain

Multiple strands of cellulose are heldtogether by hydrogen bonds makes arigid structure

Is a major component of the tough wallsthat enclose plant cells

Other Uses for Carbohydrates


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Cell surface markers carbohydrates attachedto parts on the cell membrane where they act

to identify the cell

ABO blood groups

are identified by

carbohydrates on

their surface

Metabolites


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The essential organic compounds are called metabolites Metabolites are formed as a result of metabolic activity

There are two types of metabolites a) Primary b) secondary

Primary metabolite: a) Biochemical intermediate andproducts of normal metabolic pathway E.g.: Amino acids,

nucleotides ,sugars b) Animal tissues posses only primary metabolite

Secondary metabolite : They are the products formed byalteration of normal or primary metabolite Eg.: alkaloids,flavanoids, colored pigments, scent, gums

The entire collection

Biomacromolecules


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The acid soluble pool contains chemicals withsmall molecular mass 18-800 (Da) are

biomicromolecules

The acid insoluble pool contains chemicalswith generally large molecular mass more

than 800 (Da) are biomacromolecules E.g.:

proteins, nucleic acids and polysaccharides

Metabolism


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The sum total of the chemical processes that occur in living

organisms, resulting in growth, production of energy,elimination of waste material, etc.

Anabolism- build up of complex molecules E.g.: proteins

from amino acids Catabolism- break down of complex molecules E.g.:

Energy liberated during catabolic reaction ,formation of

lactic acid from glucose in skeletal muscles

Metabolic pathway is multistep chemical reactions where

each step is catalyzed by different components of either

same enzyme complex or different enzyme

Fates ofOrganic

ORGANIC BUILDING BLOCK MOLECULESMonosaccharides

Amino acids

Acetates


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g

Building

Blocks inATP

Metabolism

Acetates

Nucleotide bases

Polymers&

other

energy

rich

molecules

CO2&

H2O

anabolicprocesses

catabolic

processes

ATP

ADP+Pi

energyenergy

Enzymes


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Enzymes are proteinaceous substances produced by living cells that catalyzebiochemical pathway

Term enzyme coined by Willy Kuhne

All known enzymes are proteins but all proteins are not enzymes

Non protein enzymes are:

a) Ribozymesb) Ribonuclease-p

c) Peptidyl transferase

Enzymes are globular,they have 3-D confirmation with one or more

Enzymes Act as Biological Catalysts


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y g y

Catalysts are inorganic molecules that speed upchemical reactions

- catalysts remain unchanged by the reaction that theyspeed up.

-one molecule of catalyst can catalyze (start) manychemical reactions

Enzymes speed up reactions in living things

-enzymes are not changed by the reaction they speed

up- one molecule of enzyme can catalyze (start) many

reactions

Active Site


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Active Site

Enzymes have an area called an active site.- the active site is where the chemical reaction

occurs

The Shape of the Enzyme Determines

Function


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Function

The active site of the enzyme fits with onlyone type of molecule known as the substrate.

Substrate is the molecule that the enzyme

acts on. The fact that the active site can only accept

one type of substrate is known as enzyme

specificity

Enzyme Reactions


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Written as :

Enzyme+ Substrate ES Enzyme + Product

- ES refers to the enzyme substrate complex,the time when thesubstrate joins with

the active site.

ExampleCatalase + 2H2O2 ES Catalase + 2H2O + O2enzyme substrate enzyme enzyme product product

substrate

complex

Enzyme Inhibitors


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Inhibitors control the rate of enzyme activity- if there is too much of an enzymes product,

inhibitors can slow or even stop an enzymes

activity Two types of Inhibition

- Competitive Non Competitive

Competitive Inhibition


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The inhibitor is a molecule that can occupy partof the active site

While the inhibitor is in the active site, substrate

cant bind with the enzyme inhibitors competewith the substrate for the active site

inhibitor competes with substrate inhibitor blocks the active site

Noncompetitive Inhibition


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The inhibitor binds with the enzyme at a site away fromthe active site.

Inhibitor causes enzyme to change shape prevents

substrate from entering the active site

Inhibitor binds with enzyme Enzyme changes shape keeps

substrate from active site

Co-Enzymes and Co-factors


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Co Enzymes and Co factors

Co-enzymes and Co-factors are molecules thathelp certain enzymes to catalyze a reaction

- co-enzymes and co-factors often act as

carriers of electrons, atoms or functionalgroups needed to complete a reaction.

Co-Enzymes and Co-Factors


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- while they bind to an enzymes active site, and

participate in the reaction, they are not changed bythe reaction and arent considered substrates.

- Co-enzymes are organic molecules and include:

NAD, NADP, FAD, vitamin B 1, vitamin B 6, andvitamin B 12

- Co-factors are inorganic molecules and includedietary minerals like zinc, iron, copper & potassium

Denatured Enzymes


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y

Enzymes are proteins and if they are exposed to extremes oftemp or pH lose their shape

- if a protein loses its shape, it loses its function

- a protein that loses its shape is said to be denatured

- if an enzyme is denatured, substrate cant enter the active

site

extreme

tempor

pH

Common Enzymes


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Amylase - breaks down starch

Catalase breaks down H2O2

DNA polymerase joins DNA nucleotides to build DNA

Lipase break apart fats

Lactase breaks apart lactose milk sugar

Protease- breaks apart protein molecules

How do enzymes bring about high rate

of chemical conversions


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of chemical conversions

For any chemical to react ,they must collide,

collision

Occurs when certain molecules pick energy

After picking energy ,the reactant /substrate

reachesHigh energy state called Transition state

Chemicals react only in transition state ,

The difference in average energy content of (s)

from that of this transition state is called activation

energy

Properties of Enzymes


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All enzymes are proteins, enzymatic proteins are globular in nature

Biocatalyst : They catalyze the biochemical reactions , they either initiate

biochemical reaction nor change equilibrium

They speed up the rate of chemical reaction and helps to attain equilibrium

Complexes : E+ S ESEPE+P

Reversibility : Enzymes catalyze the reaction in both directions E.g. Fumarase

changes malic acid to fumaric acid @ 7.8 pH while @ pH 6.2 it promotes reverse

reactions

Enzyme concentration : Only small quantity of enzyme is sufficient for bringing

about biochemical change

Temperature and pH Sensitivity : Enzymes operate @ temperature of 25-35c .

Enzymes become inactive on freezing and denatures above 45c .Enzymes showoptimum activity @ neutral pH


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What are the factors affectingEnzyme Activity?

20C (increasing temperature)


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Increasing the temperature will lead to the increase

in kinetic energy of enzyme and substrate molecules.

Enzyme and substrate molecules move withincreasing speed and collide more frequently witheach other.

This increases the rate ofenzyme-substrate complexformation This increases the rate ofenzyme-substrate complex formation and productformation.

Rate of reaction increases

37C


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As the temperature continues toincrease, the rate of enzyme activity alsoincreases until the optimaltemperature

is reached.

Optimal temperature is the temperature

at which the enzyme works best. Rate ofproduct formation is highest!

Beyond Optimal Temperatures


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At high temperatures (>60C), weak bonds

within the enzyme molecule are broken Enzyme loses its shape and its active site.

Loss ofshape leads to a loss offunction.

Enzyme is said to have denatured Denaturation is the change in 3D structure of

an enzyme or any other protein caused byheat or chemicals such as acids or alkali,causing it to lose its function.

Denaturation


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Different enzymes denature at different temperatures. Most enzymes denature at

temperatures higher than 60C. However, there are some enzymes that stay active even

at high temperatures like 80C (Enzymes in the bacteria Thermus aquaticus)

Effect of pH on enzyme activity


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Enzyme works best within a narrow pHrange

Each enzyme works best at particular pH,

known as its optimum pH level.

At extreme pH levels, enzymes lose their

shape and function and become

denatured.

Effect of pH on enzyme activity


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Effect of Substrate on Enzyme Activity


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An increase in enzyme concentration increases therate

of reaction until it reaches a max velocity known as

Vmax

When all the active sites are occupied by the

substrate

Complex. There is no further increase in the velocityof enzymes catalyzed reaction

MichelsMenten constant or Km value is defined

asThe substrate concentration to produce half max

velocity V max in any enzyme catalyzed reaction

Classification of Enzymes


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Oxidoreductases/Dehydroenase Transferase

Hydrolases

Lyases (removal of double bonds)

Isomerases

Anatomy of Plants


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A tissue is group of similar and dissimilar cells having

common origin ,structure and function Based on capacity to divide cells can be

a) Meristems

b) Permanent

Meristematic tissue: a) These are the formative tissueswhich are made up of immature, and similar cells,and are in continuous state of cell divisions andforming

Features of Meristem:

a) They are found in the growing regions of the plantbody

b) Cells are compactly arranged without intracellularspaces

c) They are various shapes like oval, rectangular,polygonal

d) Cells have prominent nucleus ,vacuole generallyabsent


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Classification of meristem based on position:

A) Apical meristem: Found at root tip and shoot tip

B) Intercalary : These are found at the base and on lateral side, they show rapid growth

C) Lateral : They are found in sides of the stem and root

Permanent Tissues: The derivatives of meristematic tissue undergo differentiation anddevelop into permanent tissue .

The cells have definite shape and size and they never divide

A) Simple : Tissue containing similar structure and carry out similar function

a) Parenchyma b) collenchyma c) sclerenchyma

A) Parenchyma : a) It is simple permanent living storage tissues found in soft parts ofplant body

b) It appears in various shapes like oval, polygonal ,cells can be loosely arranged orcompactly arranged

C) Cells are thin made of cellulose ,vacuole are large and prominent

It functions in buoyancy , food and water conducting and secondary growth


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B) Collenchyma : a) It is simple permanent, living mechanical tissue

b) It is found in aerial part of petiole, pedicle and other tender parts

c) It appears shapes like polygonal ,irregular shapes, cell wall is thick due to deposition

of pectin ,vacuolated cytoplasm

It function in mechanical support, take part in photosynthesis and secondary growth

C ) Sclerenchyma : a) It is found in all parts of body along with xylem and phloem

b) It appear spindle shaped (star shaped) ,it is compactly arranged withoutintercellular spaces

c) Cell is thick due to deposition of lignin ,dont have cytoplasm and nucleus

It functions as mechanical support, rigid to various part of plant, it helps in food and

water conducting

COMPLEX PERMANENT TISSUES: They are composed of several kinds of cells andperform a common function . They are two types of tissues:

A) Xylem

B) Phloem

Xylem : It is type of complex tissue which help in conducting of water in the plant .Xylem has four different kind of cells a) Tracheids b) Tracheae (vessels) c) Xylem


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Xylem has four different kind of cells a) Tracheids b) Tracheae (vessels) c) Xylemfibers and d) Xylem parenchyma (wood parenchyma)

Tracheids : These are primitive water conducting cells found in pertridophytes, gymnosperms

Their cell wall is thick due to deposition of lignin ,help in conduction of water

Cells are dry without nucleus and cytoplasm

Tracheae :

Vessels are elongated cylindrical tube like structures with hard , thick lignified walls

They are found in almost all angiosperms ,vessels also occur in some petridophytes

The cell wall is thick due to deposition of lignin but not uniform distribution

Xylem parenchyma:

It is the living component of xylem

They help in better conduction of food and water

Xylem fiber :

They provide mechanical support and strength to xylem


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Phloem : It is type of complex permanent tissue which help in

food conduction .

The components of phloem are a) Sieve cells b) companion cells

c) phloem parenchyma d) phloem fiber

A) sieve cells :

a)They are narrow, elongated cells with tapering ends

b)These cells have sieve areas (perforated areas) throughout

lateral walls

B) Companion cells :

a) They are parenchyma cells associated with sieve tube cells

,they are thin walled ,elongated

b) They appear small rounded, triangular, or rectangular cells

c) They have dense cytoplasm, a prominent nucleus, cytoplasm

is granular

They help in conduction of food and play role in maintaining

pressure gradient


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C ) Phloem parenchyma :

a) They are living cells with distinct cytoplasm and nucleus

b) They contain crystals, tannins and mucilage

c)Cells are elongated , broadly cylindrical in shape

They help in storage of organic food material like starch, tannin, and help in

translocation of food materials

D) Phloem fibers :

a) Cell wall is thick, lignified with pits

b) They occur in groups , as sheets or cylinders

Phloem give mechanical support to tissues and organs, used in making ropes ,threads

Fig. 35-10e

3 m Sieve-tube elements:longitudinal view (LM)


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Sieve-tube element (left)and companion cell:cross section (TEM)

Sieve plate

Companioncells

Sieve-tubeelements

Plasmodesma

Sieveplate

Nucleus ofcompanioncells

Sieve-tube elements:longitudinal view Sieve plate with pores (SEM)

10 m

30 m

Tissue System

and Its Functions

Component Tissues Location of Tissue

Systems

Dermal Tissue Epidermis


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System

protection prevention of

water loss

p

Periderm (in older

stems and roots)

Ground Tissue

System

photosynthesis

food storage

regeneration

support

protection

Parenchyma tissue

Collenchyma tissue

Sclerenchyma tissue

Vascular Tissue

System transport of water

and minerals

transport of food

Xylem tissue

Phloem tissue


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Diagnostic Features of a Dicot Root

* Presence of thin walled cells in the

epiblema.

* Absence of cuticle, and stomata.

* Presence of unicellular root hairs.

* Absence of hypodermis.

* Presence of passage cells and casparian

thickenings in the endodermis.

* Presence of uniseriate pericycle made up

of parenchyma.

* Presence of conjuctive tissue.

* Absence of pith.

* Presence of radial vascular bundles

exhibiting tetrach condition with exarch

xylem.


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Diagnostic Features of a Monocot Root

* Presence of thin walled cells in the

epiblema.

* Absence of cuticle and stomata.

* Presence of unicellular root hairs.

* Presence of passage cells andcasparian thickenings in the

endodermis.

* Presence of parenchyma cells in the

pericycle.

* Presence of conjuctive tissue.

* Presence of a distinct pith.* Presence of radial vascular bundles

with polyarch condition and an exarch

xylem.


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Diagnostic Features of a Monocot Stem

* Absence of trichomes.

* Presence of stomata.

* Presence of a hypodermis made up of

sclerenchyma.* Presence of undifferentiated ground tissue.

* Presence of numerous vascular bundles

irregularly scattered with cerifugal arrangement.

* Vascular bundles are conjoint, collateral & closed

with endarch xylem.

* Presence of only two protoxylem & twometaxylem vessels in each bundle.

* Presence of a lysigenous cavity.

* Absence of phloem parenchyma.

* Presence of a bundle sheath made up of

sclerenchyma.


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Diagnostic Features of a Young Dicot Stem

Following are some of the diagnostic features of

a young dicot stem

* Presence of cuticle and trichomes.

* Presence of stomata.

* Presence of a hypodermis made up ofcollenchyma.

* Presence of a wavy endodermis containing

numerous starch grains.

* Presence of a bundle cap above each vascular

bundle, formed by sclerenchyma.

* Presence of eight vascular bundles, arranged

in the form of a broken ring.

* Presence of conjoint, collateral and open

vascular bundles with an endarch xylem.

Excretion


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Animals accumulate ammonia, urea, uric acid, carbon

dioxide, water and ions like Na+, K+, Cl, phosphate, sulphate,etc., either by metabolic activities or by other means likeexcess ingestion

The nitrogenous wastes. Ammonia, urea and uric acid arethe major forms of nitrogenous wastes excreted by theanimals

Definition : Excretion is the physiological process ofeliminating the nitrogenous waste substances from the body

Fats and carbohydrates -----metabolized ---------> CO + HOwith liberation of energy, Proteins ------- metabolized -----CO + HO + ammonia

Ammonia is highly toxic ,it should be disposed off from body

or converted into less toxic substances like urea or uric acid The process of excreting ammonia is Ammonotelism. Many

bony fishes, aquatic amphibians and aquatic insects areammonotelic in nature.


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Different animals expel different nitrogenous

compounds. On the basis of the type of nitrogenousend product. There are 3 modes of excretion. Theyare:

(a) Ammonotelism :It is the type of excretion inwhich ammonia is the main nitrogenous wastematerial. Such animals are called ammonotetic E.g:aquatic animal groups like sponges, coelentrates,crustaceans,

(b) Ureotelism : It is a type of excretion where ureais the main nitrogenous wa

Movement of Water.pptx

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