Biology Form 4 Notes ; Dinamic of Cells

8/10/2019 Biology Form 4 Notes ; Dinamic of Cells

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CELL MEMBRANE

cytoplasm

Plasma membrane based on fluid – mosaic

hypothesis



Membran Sel- Hipotesis Bendalir Mozek

O2 , CO2

Glukosaion

(Membentuk tapak penerima

dengan protein pembawa)

The lipid

molecules

are

moving tomake the

bilayer

f lu id in

nature.Cholesterol in the membrane

helps to make the ‘lipid fluid’

more viscous in the cell

membranel

Allows small,

nonpolar and fat

soluble molecules topass through it eg.

water, fatty acid, gas

The carrier

and channel

proteins help

to move

polar/charged and

bigger

molecules

through the

membrane

eg. ions,

glukose,

amino acid

Explain the

fluid – mosaic

hypothesis ofthe cell

membrane.

polysaccharides Channel in

protein

molecule

Phospholipid

bilayer

Protein molecules scattered throughout and moving

in / outside the menbrane forming mosaic structureExternal of the cell

Internal of the cell

cytoplasm protein

cholesterol

Carbohydrate(sugar)

Channel protein



PERGERAKAN

BAHAN MERENTASI

MEMBRAN SEL

Passiv e transpo rt

Simple diffusionFacillitated diffusion

Active transport

osmosis

Movement of (solute) molecules from a

region of higher concentration to a region of

lower concentration (passively) untill itreaches equilibrium (the presence of

membrane is not necessary)

Movement of water molecules

(solvent) from a region of higher

water potential/ lower osmotic

concentration to a region of lower

water potential/ higher osmotic

concentration through partially

permeable membrane (eg. cell memb rane, viskin g tubing ) until

equilibrium is reached.

Higher osmotic

concentration of solution

causes increase in

osmotic pressure

example- diffusion of

water into root hairs

It is a diffusion

of solvent

molecules

Water

molecule

Partiallypermeable

membrane

Sugar

molecule

Cell in a su gar solut ion

Isotonic sugar solution has

the same osmotic

concentration to the osmotic

concentration in the cell sap

Hypotonic solution- its

osmotic concentration is lower

than the cell sap.

Hypertonic solution- its

osmotic concentration ishigher than the cell sap.

Movement of solute molecules / ions

from a region of lower concentration

to a region of higher concentration (

against the concentrat ion gradient )

actively (using the energy from cel l

metabol ism ) across cell membrane.It requires a carrier protein in the cell

membrane. ATP molecules bind to the

carrier protein molecule, make it

possible to change shape and carries

solute molecules across the cell

membrane. Example- movement of

mineral ions into root hairs andglucose molecules into ileum.

Passive diffusion ( needs no energy ) of

(polar) solute molecules / ions from higher

concentration of solutes region to lower

concentration across the cell membrane ,facillitated by channel protein / carrier

protein.

Solute molecule binds itself to

receptor site in the membrane

and carried through the

channel of protein molecule

example- diffusion od oxygen/ CO2

across bilipid layer of cell membrane

Example- diffusion of glucose molecules into red

blood cell



DIFFUSION



DIFFUSION

A B C

A - A purple crystal is

placed at the bottom of test

tube containing water

B – appearance of water

after 30 minutes

C- pink solution throughout

in the test tube

1. Explain the appearance ofsolution in test tube B and

C

2. Define operationally the

process of diffusion based

on the observations in all

the test tubes.

3. Does diffusion need a

partially permeable

membrane?

4. Give one example of this

process in animal and

plant.



TRANSPORT OF MATERIALS ACROSS CELL MEMBRANE

1. Describe the

structure of :

a. Alveolus

b. Blood capillary

2. Where can the

alveolus be found?

3. Why does the

diffusion of oxygen

and carbon dioxideoccur in the direction

as shown in the

Figure?

4. Explain the nature of

the alveolus wall?

5. Where does it occur

in plant?

6. How would the

diffusion process in

the Figure be slowed

down?

DIFFUSION OF OXYGEN GAS AND CARBON DIOXIDE

GAS IN ALVEOLUS

Blood

capillary



OSMOSISNote:

High water concentration = high water

potential (and low osmotic pressure /lowosmotic concentration )

Osmosis is the diffusion of water (

solvent) molecules down the water

potential gradient, through a

partially permeable membrane.

It stops when water moleculesreaches an equilibrium on both

sides of the membrane. At this stage

rate of water movement across the

membrane in both directions is

equal.

The partially permeable membrane

allows small particles like water molecules only to pass through it.

Why can’t solute molecules like

glucose or sucrose molecules pass

through the semi-permeable

membrane?

Give one example of omosis in

animal and plant.



Experiment On Osmosis



OSMOTIC CONCENTRATIONS





OSMOSIS

The number of water

molecules go in and out

is about equal.

Net movement of water

molecules out of the cell

Net movement of water

molecules into the cell

Surrounding sugar concentration:

(a) Isotonic

(b) hypertonic

(c) hypotonic

What would finally happen to cellin (c)?

sugar

solutionerythrocyte



TURGIDITY OF CELL

Cell a – The plant cell is 1……………. ………………

The cell is placed in the 2…………………………..

Solution. Water molecules diffuse into the cell by3……………….

A cell in this condition is characterised by :

4…………………………………………………………..

5…………………………………………………………..

6………………………………………………………….

Cell b- a plant cell in a 7…………………condition

The cell is placed in a 8………………… …………

solution. Water molecules diffuse 9………….. …

by 10……………… …………..

A cell in this condition is characterised by :

11………………………………………………………….

12………………………………………………………….

13………………………………………………………….

Turgidity of plant cell is very important because :

14…………………………………………………………





FACILITATED DIFFUSION



FACILLITATED DIFFUSIONThe Figure shows a facillitated

diffusion process by which a

glucose molecule is transported

acros the cell membrane.

The sequences of the process are :

1.……………………………………..

2.……………………………………..

3 dan 4………………………………

……………………………………….

5..…………………………………….

1

2

3

4

5

The characteristics of afacillitated difffusion are :

1. The (solute) molecules that are

transported are ……………….

and ……………………

2. The molecules move from a

region of (a)……… ……… to a

region of (b)…………. ………

down the (c)………… …………

3. The molecules move across

the cell membrane with the

aids of (d)……….. …………… or

( e) …….. ……….

4. It is a (f)………… ………….. Andrequires no energy.



ACTIVE

TRANSPORT1. Describe the stages of active

transport process based on the

diagram:

A.………………………………………

B……………………………………….

C……………………………………….

D……………………………………….

E………………………………………

2. In active transport, a carrier

protein requires …………. In the

form of ……….. to ………… ions /

solute molecules across the cell

membrane.

3. The direction of the process is

………….the concentration

gradient of the ……………..

4. In animals it takes place in………………………( give two

examples)

5. In plants it takes place in

………………………(two examples)

6. The ATP molecule binds to the

carrier protein to form……..……

and ……………….

A

B

C

D

E

Direction of solute

molecules / ions



REFLECTION a) Name the structures

in Figure 1, 2 and 3.

b) Name the parts

labelled A, B, C, P, Q, R

and S

Figure 1

Figure 2Figure 3

c) Explain the movementof the following

substances in Figure

1:

i) oksygen molecule

ii) chloride ions

iii)glucose molecules

d) Describe

the function

of the

organelles inFigure 2 and

3



REFLECTION

1. Name the organelles R,S and T.

2. State the function of each organelle.

3. Where are the organelles R, S and T most abundantly

found in human being? Explain.

4. Name the fluid X, membrane D, membrane L,

structure Y and Z

5. What would happen to the cell if the organelles R and

S are absent?

Organelle R

Organelle S

Structure Z

Organelle T

Structure Z

membrane D

Organelle SMembrane L



OSMOSIS

Membran

separa telapMolekul airMolekul gula

Rajah 1 menunjukkan satu

proses fizik yang berlaku

melalui membran sel ataumembran separa telap.

1) Namakan proses fizik

tersebut

2) Tunjukkan dengan lukisan

anak panah pergerakanmolekul-molekul melalui

membran separa telap.

Bilakah kadar pergerakan

bersih molekul-molekul

tersebut mencapai

keseimbangan?

3. Bolehkan molekul gula melalui membran separa telap? Mengapa?4. Beri satu contoh dimana proses fizik dalam Rajah 1 berlaku dalam

a) tumbuhan

b) haiwan atau manusia

5. Lukis rajah menunjukkan situasi akhir bagi larutan A dan larutan B pada Rajah 1.

Larutan A Larutan B

Biology Form 4 Notes ; Dinamic of Cells

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