CAMPBELL Outline BIOLOGY - Napa Valley College Pages 120 Fall 2014 New... · CAMPBELL BIOLOGY Reece •Urry ... Right-click slide / select “Play ... Like carbohydrates, lipids are

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CAMPBELL

BIOLOGYReece • Urry • Cain • Wasserman • Minorsky • Jackson

© 2014 Pearson Education, Inc.

TENTH

EDITION

CAMPBELL

BIOLOGYReece • Urry • Cain • Wasserman • Minorsky • Jackson

TENTH

EDITION

5The Structure

and Function of

Large

Biological

MoleculesDr Burns

NVC

Outline

I. Macromolecules

II. Carbohydrates – simple and complex

III. Lipids – triglycerides (fats and oils),

phospholipids, carotenoids, steroids, waxes

IV. Proteins – enzymes, keratin,

V. Nucleotides – ATP, NAD+

VI. Nucleic Acids – DNA & RNA

Overview: The Molecules of Life

All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids

Macromolecules are large molecules composed of thousands of covalently connected atoms

Molecular structure and function are inseparable


Macromolecules are polymers, built from

monomers

A polymer is a long molecule consisting of many similar building blocks

The repeating units that serve as building blocks

are called monomers

Three of the four classes of life’s organic molecules are polymers

Carbohydrates

Proteins

Nucleic acids


Polymers

Many biological molecules formed by linking a

chain of monomers

A dehydration reaction occurs when two

monomers bond together through the loss of a water

molecule

Polymers are disassembled to monomers by

hydrolysis, a reaction that is essentially the reverse

of the dehydration reaction

Enzymes are specialized macromolecules that

speed up chemical reactions such as those that

make or break down polymers

The Synthesis and Breakdown of Polymers


2


Animation: Polymers

Right-click slide / select

“Play”

Figure 5.2a

(a) Dehydration reaction: synthesizing a polymer

Short polymer Unlinked monomer

Dehydration removesa water molecule,forming a new bond.

Longer polymer

1 2 3 4

1 2 3

Figure 5.2b

(b) Hydrolysis: breaking down a polymer

Hydrolysis addsa water molecule,breaking a bond.

1 2 3 4

1 2 3

Examples of Organic Compounds

1. Carbohydrates – sugars, polymers of sugars

2. Lipids – triglycerides (fats and oils),

phospholipids, steroids, waxes

3. Proteins – enzymes, keratin, actin

4. Nucleic Acids – DNA & RNA

Carbohydrates serve as fuel and building

material

Carbohydrates include sugars and the

polymers of sugars

The simplest carbohydrates are

monosaccharides, or simple sugars

Carbohydrate macromolecules are

polysaccharides, polymers composed of

many sugar building blocks

Functions of Carbohydrates

1. Rapidly Mobilized Source of Energy

Monosaccharides and disaccharides

2. Energy storage

Glycogen in animals

Starch in plants

3. Structural

In cell walls bacteria and plants (Cellulose).

In exoskeletons (Chitin).

4. Coupled with protein to form glycoproteins

Important in cell membranes

3

Simple Carbohydrates Sugars

Monosaccharides have molecular formulas that

are usually multiples of CH2O

Glucose (C6H12O6) is the most common

monosaccharide

Monosaccharides are classified by

The location of the carbonyl group (as aldose or

ketose)

The number of carbons in the carbon skeleton


Figure 5.3a

Aldose (Aldehyde Sugar) Ketose (Ketone Sugar)

Glyceraldehyde

Trioses: 3-carbon sugars (C3H6O3)

Dihydroxyacetone

Figure 5.3b

Pentoses: 5-carbon sugars (C5H10O5)

Ribose Ribulose


Figure 5.3c


Hexoses: 6-carbon sugars (C6H12O6)

Glucose Galactose Fructose

Though often drawn as linear skeletons, in

aqueous solutions many sugars form rings

Monosaccharides serve as a major fuel for

cells and as raw material for building molecules


4

Figure 5.4

(a) Linear and ring forms

(b) Abbreviated ring structure

1

2

3

4

5

6

6

5

4

32

1 1

23

4

5

6

1

23

4

5

6

A disaccharide is formed when a dehydration

reaction joins two monosaccharides

This covalent bond is called a glycosidic

linkage


Disaccharide


Animation: Disaccharide

Right-click slide / select “Play”

Figure 5.5

(a) Dehydration reaction in the synthesis of maltose

(b) Dehydration reaction in the synthesis of sucrose

Glucose Glucose

Glucose

Maltose

Fructose Sucrose

1–4glycosidic

linkage

1–2glycosidic

linkage

1 4

1 2

Reactions where two molecules are linked together

and water is removed is …

1. Condensation or

dehydration

2. Hydrolysis

Conde

nsatio

n

Hyd

roly

sis

50%50%

Complex Carbohydrates

5

Polysaccharides

Polysaccharides, the polymers of sugars, have

storage and structural roles

The structure and function of a polysaccharide are

determined by its sugar monomers and the

positions of glycosidic linkages

Types

1. Starch

2. Glycogen

3. Cellulose

4. Chitin


Complex carbohydrates - Polysaccharide


Animation: Polysaccharides


Functions of Carbohydrates

1. Rapidly Mobilized Source of Energy

Monosaccharides and disaccharides

2. Energy storage - Polysaccharides

Glycogen in animals

Starch in plants

3. Structural - Polysaccharides

In cell walls bacteria and plants (Cellulose).

In exoskeletons (Chitin).

4. Coupled with protein to form glycoproteins

Important in cell membranes

Structure of Complex Carbohydrates

Polysaccharides - Long chains of saccharides

(sugars) – 100s to 1000s

Cellulose, starch and glycogen consist of chains

of only glucose.

Chitin consists of chains of glucose with N-acetyl

groups

Structure of Complex Carbohydrates

The differences between the complex

carbohydrates is in the structure – branched,

unbranched, spiral, hydrogen-bonded.

Cellulose is tightly packed and hard to digest

Starch is coiled and may be branched and is easier

to digest

Glycogen is coiled with extensive branching and is

even easier to digest.

6

Figure 5.6

(a) Starch:a plant polysaccharide

(b) Glycogen:an animal polysaccharide

Chloroplast Starch granules

Mitochondria Glycogen granules

Amylopectin

Amylose

Glycogen

1 m

0.5 m

Polysaccharides in Plants for Energy Storage

Starch, a storage polysaccharide of plants, consists entirely of glucose monomers

Plants store surplus starch as granules within amyloplasts

The simplest form of starch is amylose


Starch

Starch – form stored in plants, coiled, mainly α

1-4 glycosidic linkage. If branched then will

also have α 1-6 glycosidic linkage, stored in

amyloplasts. Plants used for energy storage,

easy to digest

Sources: Potatoes, rice, carrots, corn

Function: Energy Storage

Starch

Types of starches:

Amylose – not branched

Amylopectin – branched, more common

Figure 5.6a

Storage structures(plastids)containing starchgranules in a potatotuber cell

50 µm

(a) Starch

Amylose (unbranched)

Amylopectin(somewhatbranched)

Glucosemonomer

7

Glycogen

Glycogen – form stored in animals for energy,

coiled, highly branched, contains α 1-4

glycosidic linkage and α 1-6 glycosidic linkage,

easy to digest

Found in animals: stored mainly in liver and

muscle

Function: Energy Storage

Question

Why do we store glycogen in our muscles?

Figure 5.6b

Glycogengranules inmuscletissue Glycogen (branched)

1 µm

(b) Glycogen

Structural Polysaccharides in Plants - Starch

The polysaccharide cellulose is a major

component of the tough wall of plant cells

Like starch, cellulose is a polymer of glucose,

but the glycosidic linkages differ

The difference is based on two ring forms for

glucose: alpha () and beta ()


Cellulose

Cellulose – straight chains of glucose, -OH

groups H-bond to stabilize chains into tight

bundles, β 1-4 glycosidic linkage, hard to

digest

Used by plants for structure and in cell walls.

Figure 5.7a

(a) and glucose ring structures

Glucose Glucose

4 1 4 1

8

Figure 5.7b

(b) Starch: 1–4 linkage of glucose monomers

(c) Cellulose: 1–4 linkage of glucose monomers

41

41


Polymers with glucose are helical

Polymers with glucose are straight

In straight structures, H atoms on one strand can

bond with OH groups on other strands

Parallel cellulose molecules held together this way

are grouped into microfibrils, which form strong

building materials for plants

Cell wall

Microfibril

Cellulosemicrofibrils in aplant cell wall

Cellulosemolecules

Glucosemonomer

10 m

0.5 m

Figure 5.8

Enzymes that digest starch by hydrolyzing

linkages can’t hydrolyze linkages in cellulose

Cellulose in human food passes through the

digestive tract as insoluble fiber

Some microbes use enzymes to digest cellulose

Many herbivores, from cows to termites, have

symbiotic relationships with these microbes


Why do we care?

Chitin, another structural polysaccharide, is found

in the exoskeleton of arthropods.

Contains N-acetyl group which hydrogen bond. It is

cross-linked with protein to form a strong

exoskeleton for insects and crustaceans

Chitin also provides structural support for the cell

walls of many fungi


Structural Polysaccharides - ChitinFigure 5.9

Chitin forms the exoskeletonof arthropods.

The structureof the chitinmonomer

Chitin is used to make a strong and flexiblesurgical thread that decomposes after thewound or incision heals.

9

Figure 5.8a

The structure of the chitinmonomer

Question

Is Chitin α or β linkage?

Glycoproteins

Glycoproteins – carbohydrate + protein on

outer surface of cell membranes – we will

return to this when we study cell membranes

The form of carbohydrate stored in animals is?

1. Starch

2. Glycogen

3. Cellulose

Sta

rch

Gly

cogen

Cel

lulo

se

33% 33%33%

Which carbohydrate contains nitrogen?

1. Starch

2. Cellulose

3. Glycogen

4. Chitin

Sta

rch

Cel

lulo

se

Gly

cogen

Chiti

n

25% 25%25%25%

Starch is composed of glucose molecules

joined by what kind of covalent bond?

1. β 1-4 Glycosidic

linkage

2. α 1-4 Glycosidic

linkage

10

Lipids

Like carbohydrates, lipids are mainly made of carbon, hydrogen and oxygen

They are not soluble in water, they are soluble in nonpolar solvents

Types:

1. Triglycerides (Fats)

2. Phospholipids

3. Carotenoids

4. Steroids

5. Waxes

Lipids are a diverse group of hydrophobic

molecules

Lipids are the one class of large biological

molecules that do not form polymers

The unifying feature of lipids is having little or no

affinity for water

Lipids are hydrophobic because they consist

mostly of hydrocarbons, which form nonpolar

covalent bonds

The most biologically important lipids are fats,

phospholipids, and steroids


I. Lipid - Triglycerides

Function

Energy storage, insulation, protection

Triglycerides (triacylglycerol) are three fatty

acids joined to glycerol

The fatty acids are covalently linked by an

ester linkage through a condensation reaction

Figure 5.10a

(a) One of three dehydration reactions in the synthesis of a fat

Fatty acid(in this case, palmitic acid)

Glycerol

Figure 5.10b

(b) Fat molecule (triacylglycerol)

Ester linkageEster vs Ether

11

Triglycerides

Butter, lard (animal fat), and vegetable oils

are all triglycerides

Differences are in the structure of the fatty

acids

Fatty acids vary in length (number of carbons) and

in the number and locations of double bonds

Saturated fatty acids have the maximum number

of hydrogen atoms possible and no double bonds

in the carbon chain.

Unsaturated fatty acids have one or more double

bonds in the carbon chain.


Fatty Acids

Fatty Acids

Saturated fatty acids – carbon chain has no

double bonds CH3-(CH2-CH2)n-COOH

Unsaturated fatty acids – carbon chain has a

double bond

Monounsaturated fatty acids have one double

bond

Polyunsaturated fatty acids – more than one

double bond


Animation: Fats


Figure 5.11

(a) Saturated fat(b) Unsaturated fat

Structuralformula of asaturated fatmolecule

Space-fillingmodel of stearicacid, a saturatedfatty acid

Structuralformula of anunsaturated fatmolecule

Space-filling modelof oleic acid, anunsaturated fattyacid

Cis double bondcauses bending.

(a) Saturated fat

Structuralformula of asaturated fatmolecule

Space-fillingmodel of stearicacid, a saturatedfatty acid

Figure 5.11a

12

Figure 5.11b (b) Unsaturated fat

Structuralformula of anunsaturated fatmolecule

Space-filling modelof oleic acid, anunsaturated fattyacid

Cis double bondcauses bending.

Fats made from saturated fatty acids are called

saturated fats, and are solid at room temperature

Most animal fats are saturated

Fats made from unsaturated fatty acids are called

unsaturated fats or oils, and are liquid at room

temperature

Plant fats and fish fats are usually unsaturated


Trans fats

Hydrogenation is the process of converting

unsaturated fats to saturated fats by adding

hydrogen

Hydrogenating vegetable oils also creates

unsaturated fats with trans double bonds

Trans fats – unsaturated oils that have been

chemically saturated so they will be solid at

room temperature (Crisco)


13

Certain unsaturated fatty acids are not synthesized

in the human body

These must be supplied in the diet

These essential fatty acids include the omega-3

fatty acids, required for normal growth, and thought

to provide protection against cardiovascular

disease


Essential fatty acids

The major function of fats is energy storage

Humans and other mammals store their fat in

adipose cells

Adipose tissue also cushions vital organs and

insulates the body


Function of Triglycerides

Which type of fatty acid does not contain a double

bond?

1. Polyunsaturated

2. Omega 3 unsaturated

3. Trans fat

4. Saturated

Poly

unsatu

rate

d

Om

ega

3 unsa

tura

ted

Tra

ns fa

t

Sat

urate

d

25% 25%25%25%

II. Lipid - Phospholipids

Function

Backbone of cell membranes

Similar structure as triglycerides but have:

Glycerol

2 fatty acids

Phosphate group (negatively charged)

R group

II. Lipid - Phospholipids

Phospholipids are amphiphathic

Phosphate end of molecule soluble in water -

hydrophilic.

Lipid (fatty acid) end is not soluble in water -

hydrophobic.

Figure 5.12

Choline

Phosphate

Glycerol

Fatty acids

Hydrophilichead

Hydrophobictails

(c) Phospholipid symbol(b) Space-filling model(a) Structural formula

Hyd

rop

hil

ic h

ead

Hyd

rop

ho

bic

tail

s

14

When phospholipids are added to water, they

self-assemble into a bilayer, with the

hydrophobic tails pointing toward the interior

The structure of phospholipids results in a

bilayer arrangement found in cell membranes

Phospholipids are the major component of all

cell membranes


Phospholipid’s role in memebranesFigure 5.13

Hydrophilichead

Hydrophobictail

WATER

WATER

III. Lipid - Carotenoids

Consist of isoprene units

Orange and yellow plant pigments

Classified with lipids

Some play a role in photosynthesis

Animals convert to vitamin A

Isoprene-derived compounds

IV. Lipids - Steroids

Structure: Four fused rings

Examples: cholesterol, bile salts, reproductive hormones, cortisol

Steroids - Functions

Functions include

Hormones - Signaling within and between cells (estrogen, testosterone, cortisol)

Cholesterol – Important part of cell membrane

Bile salts - Emulsify fat in small intestine

15

IV. Lipids - Steroids

Unlike triglycerides and phospholipids, steroids have no fatty acids

Structure is a four ring backbone, with side chains attached

Figure 5.14 Cholesterol

V. Lipids - Waxes

Covers surface of leaves of plants.

Functions

Minimizes water loss from leaves to air.

Barrier against entrance of bacteria and

parasites into leaves of plants.

This type of lipid is an important component of

membranes

1. Triglycerides

2. Phospholipids

3. Waxes

Trigly

cerid

es

Phosp

holipid

s

Wax

es

33% 33%33%

Proteins include a diversity of structures,

resulting in a wide range of functions

Proteins account for more than 50% of the dry

mass of most cells

Protein functions include catalyst, structural

support, storage, transport, cellular

communications, movement, and defense against

foreign substances


Proteins

Functions – numerous and varied include:

Facilitate chemical reactions (enzymes)

Transport

Movement of muscles

Structure

Cell signaling - Hormones (insulin)

Nutrition

Defense

Components of cell membrane

Immune response

16

Enzymes are a type of protein that acts as a

catalyst to speed up chemical reactions

Enzymes can perform their functions

repeatedly, functioning as workhorses that carry

out the processes of life


Protein Functions - Enzymes Enzymes

Enzymes are proteins that catalyze reactions = help reactions to happen – they speed up chemical reactions

They can only speed up reactions that would happen eventually (may take years)

They are usually specific for their substrates

They are not consumed (destroyed) in the process

Some enzymes need cofactors to function. Example = iron

Substrate = the

thing that is being

changed in the

reaction

Active site = Place

in the enzyme

where the substrate

binds.

Product = The

end result

Figure 5.15-a

Enzymatic proteins Defensive proteins

Storage proteins Transport proteins

Enzyme Virus

Antibodies

Bacterium

Ovalbumin Amino acidsfor embryo

Transportprotein

Cell membrane

Function: Selective acceleration of chemical reactions

Example: Digestive enzymes catalyze the hydrolysis

of bonds in food molecules.

Function: Protection against disease

Example: Antibodies inactivate and help destroy

viruses and bacteria.

Function: Storage of amino acids Function: Transport of substances

Examples: Casein, the protein of milk, is the major

source of amino acids for baby mammals. Plants have

storage proteins in their seeds. Ovalbumin is the

protein of egg white, used as an amino acid source

for the developing embryo.

Examples: Hemoglobin, the iron-containing protein of

vertebrate blood, transports oxygen from the lungs to

other parts of the body. Other proteins transport

molecules across cell membranes.

Figure 5.15-b

Hormonal proteinsFunction: Coordination of an organism’s activities

Example: Insulin, a hormone secreted by the

pancreas, causes other tissues to take up glucose,

thus regulating blood sugar concentration

Highblood sugar

Normalblood sugar

Insulinsecreted

Signalingmolecules

Receptorprotein

Muscle tissue

Actin Myosin

100 m 60 m

Collagen

Connectivetissue

Receptor proteinsFunction: Response of cell to chemical stimuli

Example: Receptors built into the membrane of a

nerve cell detect signaling molecules released by

other nerve cells.

Contractile and motor proteinsFunction: Movement

Examples: Motor proteins are responsible for the

undulations of cilia and flagella. Actin and myosin

proteins are responsible for the contraction of

muscles.

Structural proteinsFunction: Support

Examples: Keratin is the protein of hair, horns,

feathers, and other skin appendages. Insects and

spiders use silk fibers to make their cocoons and webs,

respectively. Collagen and elastin proteins provide a

fibrous framework in animal connective tissues.

Animation: Contractile Proteins

17

Animation: Defensive Proteins Animation: Enzymes

Animation: Gene Regulatory Proteins Animation: Hormonal Proteins

Animation: Receptor Proteins Animation: Sensory Proteins

18

Animation: Storage Proteins Animation: Structural Proteins

Animation: Transport Proteins Proteins

Proteins are all constructed from the same

set of 20 amino acids

Polypeptide chains are polymers built from

these amino acids

A protein is a biologically functional

molecule that consists of one or more

polypeptides

Amino Acids

Proteins are made up of the monomer = amino

acids

Amino acids are organic molecules with carboxyl

and amino groups

There are 20 amino acids, each with a different

substitution for R.

Figure 5.UN01

Side chain (R group)

Aminogroup

Carboxylgroup

carbon

19

Ionized amino acid

Ionized form

Figure 5.14Nonpolar side chains; hydrophobic


Glycine(Gly or G)

Alanine(Ala or A)

Valine(Val or V)

Leucine(Leu or L)

Isoleucine(Ile or I)

Proline(Pro or P)

Tryptophan(Trp or W)

Phenylalanine(Phe or F)

Methionine(Met or M)

Polar side chains; hydrophilic

Electrically charged side chains; hydrophilic

Aspartic acid(Asp or D)

Glutamic acid(Glu or E)

Lysine(Lys or K)

Arginine(Arg or R)

Histidine(His or H)

Glutamine(Gln or Q)

Acidic (negatively charged)

Basic (positively charged)

Asparagine(Asn or N)

Tyrosine(Tyr or Y)

Cysteine(Cys or C)

Threonine(Thr or T)

Serine(Ser or S)

Figure 5.14a

Nonpolar side chains; hydrophobic


Glycine(Gly or G)

Alanine(Ala or A)

Valine(Val or V)

Leucine(Leu or L)

Isoleucine(Ile or I)

Proline(Pro or P)

Tryptophan(Trp or W)

Phenylalanine(Phe or F)

Methionine(Met or M)

Figure 5.14b

Polar side chains; hydrophilic

Glutamine(Gln or Q)

Asparagine(Asn or N)

Tyrosine(Tyr or Y)

Cysteine(Cys or C)

Threonine(Thr or T)

Serine(Ser or S)

Figure 5.14c

Electrically charged side chains; hydrophilic

Aspartic acid(Asp or D)

Glutamic acid(Glu or E)

Lysine(Lys or K)

Arginine(Arg or R)

Histidine(His or H)

Acidic (negatively charged)

Basic (positively charged)

Amino Acid Polymers

Amino acids are linked by peptide bonds

A polypeptide is a polymer of amino acids

Polypeptides range in length from a few to more

than a thousand monomers

Each polypeptide has a unique linear sequence of

amino acids, with a carboxyl end (C-terminus) and

an amino end (N-terminus)


20

Figure 5.17

Peptide bond

New peptidebond forming

Sidechains

Back-bone

Amino end(N-terminus)

Peptidebond

Carboxyl end(C-terminus)

Protein Structure and Function

The specific activities of proteins result

from their intricate three-dimensional

architecture

A functional protein consists of one or

more polypeptides precisely twisted,

folded, and coiled into a unique shape

Figure 5.18

(a) A ribbon model (b) A space-filling model

Groove

Groove

Animation: Protein Structure Introduction

Four Levels of Protein Structure

The primary structure of a protein is its unique

sequence of amino acids

Secondary structure, found in most proteins,

consists of coils and folds in the polypeptide chain

Tertiary structure is determined by interactions

among various side chains (R groups)

Quaternary structure results when a protein consists

of multiple polypeptide chains


Figure 5.20a Primary structure

Aminoacids

Amino end

Carboxyl end

Primary structure of transthyretin

21

Primary structure, the sequence of amino

acids in a protein, is like the order of letters in

a long word

Primary structure is determined by inherited

genetic information


Primary Structure of Proteins


Animation: Primary Protein Structure


The coils and folds of secondary structure

result from hydrogen bonds between repeating

constituents of the polypeptide backbone

Typical secondary structures are a coil called an helix and a folded structure called a pleated sheet


Secondary Structure of Proteins


Animation: Secondary Protein Structure Right-

click slide / select “Play”

Secondary structure

Hydrogen bond

helix

pleated sheet

strand, shown as a flatarrow pointing towardthe carboxyl end

Hydrogen bond

Figure 5.20c

Tertiary structure is determined by interactions

between R groups, rather than interactions

between backbone constituents

These interactions between R groups include

hydrogen bonds, ionic bonds, hydrophobic

interactions, and van der Waals interactions

Strong covalent bonds called disulfide bridges

may reinforce the protein’s structure


Tertiary Structure of Proteins

22


Animation: Tertiary Protein Structure


Figure 5.20e

Tertiary structure

Figure 5.20f

Hydrogenbond

Disulfidebridge

Polypeptidebackbone

Ionic bond

Hydrophobic

interactions and

van der Waals

interactions

Quaternary structure results when two or more

polypeptide chains form one macromolecule

Collagen is a fibrous protein consisting of three

polypeptides coiled like a rope

Hemoglobin is a globular protein consisting of four

polypeptides: two alpha and two beta chains


Quaternary Structure of Proteins

Figure 5.20g

Quaternary structure

four identicalpolypeptides

Hemoglobin

Heme

Iron

subunit

subunit

subunit

subunit

Figure 5.20i

23

Figure 5.20j


Animation: Quaternary Protein Structure


Sickle-Cell Disease: A Change in Primary Structure

A slight change in primary structure can affect a

protein’s structure and ability to function

Sickle-cell disease, an inherited blood disorder,

results from a single amino acid substitution in the

protein hemoglobin


Figure 5.21

PrimaryStructure

Secondaryand TertiaryStructures

QuaternaryStructure

FunctionRed BloodCell Shape

subunit

subunit

Exposedhydrophobicregion

Molecules do notassociate with oneanother; each carriesoxygen.

Molecules crystallizeinto a fiber; capacityto carry oxygen isreduced.

Sickle-cellhemoglobin

Normalhemoglobin

10 m

10 m

Sic

kle

-cell

hem

og

lob

inN

orm

al

hem

og

lob

in

1

2

3

4

5

6

7

1

2

3

4

5

6

7

What Determines Protein Structure?

In addition to primary structure, physical and

chemical conditions can affect structure

Alterations in pH, salt concentration, temperature,

or other environmental factors can cause a

protein to unravel

This loss of a protein’s native structure is called

denaturation

A denatured protein is biologically inactive


Figure 5.22

Normal protein Denatured protein

tu

24

Protein Folding in the Cell

It is hard to predict a protein’s structure from its

primary structure

Most proteins probably go through several stages on

their way to a stable structure

Chaperonins or chaperones are protein molecules

that assist the proper folding of other proteins

Diseases such as Alzheimer’s, Parkinson’s, and

mad cow disease are associated with misfolded

proteins


Figure 5.21

Hollowcylinder

Cap

Chaperonin(fullyassembled)

Polypeptide

1 An unfoldedpolypeptideenters thecylinderfromone end.

2 Cap attachmentcauses thecylinder tochange shape,creating ahydrophilicenvironmentfor polypeptidefolding.

3 The capcomes off,and theproperlyfoldedprotein isreleased.

Correctly folded

protein

Scientists use X-ray crystallography to determine

a protein’s structure

Another method is nuclear magnetic resonance

(NMR) spectroscopy, which does not require

protein crystallization

Bioinformatics uses computer programs to predict

protein structure from amino acid sequences


Determining the Structure of ProteinsFigure 5.24

DiffractedX-rays

X-raysource X-ray

beam

Crystal Digital detector X-ray diffractionpattern

RNA DNA

RNApolymerase II

EXPERIMENT

RESULTS

The Roles of Nucleic Acids

There are two types of nucleic acids

Deoxyribonucleic acid (DNA)

Ribonucleic acid (RNA)

DNA provides directions for its own replication

DNA directs synthesis of messenger RNA (mRNA)

and, through mRNA, controls protein synthesis

Protein synthesis occurs on ribosomes


Figure 5.25-1

Synthesis ofmRNA

mRNA

DNA

NUCLEUS

CYTOPLASM

1

25

Figure 5.25-2

Synthesis ofmRNA

mRNA

DNA

NUCLEUS

CYTOPLASM

mRNA

Movement ofmRNA intocytoplasm

1

2

Figure 5.25-3

Synthesis ofmRNA

mRNA

DNA

NUCLEUS

CYTOPLASM

mRNA

Ribosome

AminoacidsPolypeptide

Movement ofmRNA intocytoplasm

Synthesisof protein

1

2

3

The Components of Nucleic Acids

Nucleic acids are polymers made of monomers

called nucleotides

Each nucleotide consists of a nitrogenous base, a

pentose sugar, and one or more phosphate

groups


Nucleotide Functions

Their functions include:

Energy (ATP)

Coenzymes that aid enzyme function (NAD+)

Messengers within cells (GTP)

Nucleotide Bases

There are 5 nucleotide bases:

Adenine, Thymine, Uracil, Guanine, Cytosine

Nucleoside = nitrogenous base + sugar

Nucleotide = nucleoside + phosphate group

There are two families of nitrogenous bases

Pyrimidines (cytosine, thymine, and uracil)

have a single six-membered ring

Purines (adenine and guanine) have a six-

membered ring fused to a five-membered ring

In DNA, the sugar is deoxyribose; in RNA, the

sugar is ribose

26

Nucleic Acids

Nucleic Acids are a chain or chains of nucleotides

The nucleotides are covalently bonded by phosphodiester linkage between the phosphates and sugars

Figure 5.26

Sugar-phosphate backbone5 end

5C

3C

5C

3C

3 end

(a) Polynucleotide, or nucleic acid

(b) Nucleotide

Phosphategroup Sugar

(pentose)

Nucleoside

Nitrogenousbase

5C

3C

1C

Nitrogenous bases

Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA)

Adenine (A) Guanine (G)

Sugars

Deoxyribose (in DNA) Ribose (in RNA)

(c) Nucleoside components

Pyrimidines

Purines

Figure 5.26abSugar-phosphate backbone

5 end

5C

3C

5C

3C

3 end

(a) Polynucleotide, or nucleic acid

(b) Nucleotide

Phosphategroup Sugar

(pentose)

Nucleoside

Nitrogenousbase

5C

3C

1C

Figure 5.26c

Nitrogenous bases

Cytosine (C)

Thymine (T, in DNA)

Uracil (U, in RNA)

Adenine (A) Guanine (G)

Sugars

Deoxyribose (in DNA)

Ribose (in RNA)

(c) Nucleoside components

Pyrimidines

Purines

27

Figure 5.27

Sugar-phosphatebackbones

Hydrogen bonds

Base pair joinedby hydrogen bonding

Base pair joinedby hydrogen

bonding

(b) Transfer RNA(a) DNA

5 3

53

Figure 5.UN02

Fatty acids are joined to glycerol by what

kind of linkage?

1. Peptide

2. Gycosidic

3. Phosphodiester

4. Ester

Pep

tide

Gyc

osid

ic

Phosp

hodiest

er

Est

er

25% 25%25%25%

Important Concepts

Know the vocabulary of the lecture and reading

What are the different types of biological molecules, what are their functions? Be able to identify their structures

What are the types of carbohydrates? What types of organisms are they found in? What are their functions, identify their structures?

Be able to describe the differences in the carbohydrates’ structures and the implications these difference have on our ability to digest them

Important Concepts

What are the types of starches and what structure stores starch?

What are the different types of lipids and their

biological functions?

What is the structure of amino acids, what bond

links amino acids together? Be able to draw and

amino acid structure.

Be able to describe protein structure including

primary, secondary etc. Know what forces hold

alpha helixes and beta sheets together, know the

forces that help shape tertiary structure.

Important Concepts

Know examples of steroids and functions of

each type of steroids.

What are enzymes? What is their function, what

are their properties, what are the active site, the

substrates, and the products?

What is the structure of nucleotides, What

are nucleic acids what are their functions.

Know the monomers and polymers and what

bonds link the monomers together.

CAMPBELL Outline BIOLOGY - Napa Valley College Pages 120 Fall 2014 New... · CAMPBELL BIOLOGY Reece •Urry ... Right-click slide / select “Play ... Like carbohydrates, lipids are

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