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Chapter 5

The Structure and Function of Large Biological Molecules

PowerPoint^® Lecture Presentations for Biology

Eighth Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp

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Overview: The Molecules of Life

All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids
Within cells, small organic molecules are joined together to form larger molecules
Macromolecules are large molecules composed of thousands of covalently connected atoms
Molecular structure and function are inseparable

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Fig. 5-1

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Concept 5.1: Macromolecules are polymers, built from monomers

A polymer is a long molecule consisting of many similar building blocks
These small building-block molecules are called monomers
Three of the four classes of life’s organic molecules are polymers:

Carbohydrates
Proteins
Nucleic acids

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The Synthesis and Breakdown of Polymers

A condensation reaction or more specifically a dehydration reaction occurs when two monomers bond together through the loss of a water molecule
Enzymes are macromolecules that speed up the dehydration process
Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction

Animation: Polymers

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Fig. 5-2

Short polymer

HO

1

2

3

H

HO

H

Unlinked monomer

Dehydration removes a water

molecule, forming a new bond

HO

H₂O

H

1

2

3

4

Longer polymer

(a) Dehydration reaction in the synthesis of a polymer

HO

1

2

3

4

H

H₂O

Hydrolysis adds a water

molecule, breaking a bond

HO

H

HO

1

2

3

(b) Hydrolysis of a polymer

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Fig. 5-2a

Dehydration removes a water

molecule, forming a new bond

Short polymer

Unlinked monomer

Longer polymer

Dehydration reaction in the synthesis of a polymer

HO

H₂O

H

4

3

2

1

2

3

(a)

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Fig. 5-2b

Hydrolysis adds a water

molecule, breaking a bond

Hydrolysis of a polymer

HO

H₂O

H

3

2

1

2

3

4

(b)

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The Diversity of Polymers

Each cell has thousands of different kinds of macromolecules
Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species
An immense variety of polymers can be built from a small set of monomers

2

3

HO

H

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Concept 5.2: Carbohydrates serve as fuel and building material

Carbohydrates include sugars and the polymers of sugars
The simplest carbohydrates are monosaccharides, or single sugars
Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks

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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

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Fig. 5-3

Dihydroxyacetone

Ribulose

Ketoses

Aldoses

Fructose

Glyceraldehyde

Ribose

Glucose

Galactose

Hexoses (C₆H₁₂O₆)

Pentoses (C₅H₁₀O₅)

Trioses (C₃H₆O₃)

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Fig. 5-3a

Aldoses

Glyceraldehyde

Ribose

Glucose

Galactose

Hexoses (C₆H₁₂O₆)

Pentoses (C₅H₁₀O₅)

Trioses (C₃H₆O₃)

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Fig. 5-3b

Ketoses

Dihydroxyacetone

Ribulose

Fructose

Hexoses (C₆H₁₂O₆)

Pentoses (C₅H₁₀O₅)

Trioses (C₃H₆O₃)

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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

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Fig. 5-4

(a) Linear and ring forms

(b) Abbreviated ring structure

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Fig. 5-4a

(a) Linear and ring forms

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Fig. 5-4b

(b) Abbreviated ring structure

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A disaccharide is formed when a dehydration reaction joins two monosaccharides
This covalent bond is called a glycosidic linkage

Animation: Disaccharides

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Fig. 5-5

(b) Dehydration reaction in the synthesis of sucrose

Glucose

Fructose

Sucrose

Maltose

Glucose

(a) Dehydration reaction in the synthesis of maltose

1–4

glycosidic

linkage

1–2

glycosidic

linkage

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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

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Storage Polysaccharides

Starch, a storage polysaccharide of plants, consists entirely of glucose monomers
Plants store surplus starch as granules within chloroplasts and other plastids

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Fig. 5-6

(b) Glycogen: an animal polysaccharide

Starch

Glycogen

Amylose

Chloroplast

(a) Starch: a plant polysaccharide

Amylopectin

Mitochondria

Glycogen granules

0.5 µm

1 µm

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Glycogen is a storage polysaccharide in animals
Humans and other vertebrates store glycogen mainly in liver and muscle cells

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Structural Polysaccharides

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 (α) and beta (β)

Animation: Polysaccharides

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Fig. 5-7

(a)  and  glucose

ring structures

 Glucose

 Glucose

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

(b) Cellulose: 1–4 linkage of  glucose monomers

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Fig. 5-7a

(a)  and  glucose ring structures

 Glucose

 Glucose

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Fig. 5-7bc

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

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

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Polymers with α glucose are helical
Polymers with β 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

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Fig. 5-8

Glucose

monomer

Cellulose

molecules

Microfibril

Cellulose

microfibrils

in a plant

cell wall

0.5 µm

10 µm

Cell walls

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Enzymes that digest starch by hydrolyzing α linkages can’t hydrolyze β 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

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Fig. 5-9

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Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods
Chitin also provides structural support for the cell walls of many fungi

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Fig. 5-10

The structure

of the chitin

monomer.

(a)

(b)

(c)

Chitin forms the

exoskeleton of

arthropods.

Chitin is used to make

a strong and flexible

surgical thread.

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Concept 5.3: 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

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Fats

Fats are constructed from two types of smaller molecules: glycerol and fatty acids
Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon
A fatty acid consists of a carboxyl group attached to a long carbon skeleton

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Fig. 5-11

Fatty acid

(palmitic acid)

Glycerol

(a) Dehydration reaction in the synthesis of a fat

Ester linkage

(b) Fat molecule (triacylglycerol)

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Fig. 5-11a

Fatty acid

(palmitic acid)

(a)

Dehydration reaction in the synthesis of a fat

Glycerol

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Fig. 5-11b

(b)

Fat molecule (triacylglycerol)

Ester linkage

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Fats separate from water because water molecules form hydrogen bonds with each other and exclude the fats
In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride

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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
Unsaturated fatty acids have one or more double bonds

Animation: Fats

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Fig. 5-12

Structural

formula of a

saturated fat

molecule

Stearic acid, a

saturated fatty

acid

(a) Saturated fat

Structural formula

of an unsaturated

fat molecule

Oleic acid, an

unsaturated

fatty acid

(b) Unsaturated fat

cis double

bond causes

bending

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Fig. 5-12a

(a)

Saturated fat

Structural

formula of a

saturated fat

molecule

Stearic acid, a

saturated fatty

acid

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Fig. 5-12b

(b)

Unsaturated fat

Structural formula

of an unsaturated

fat molecule

Oleic acid, an

unsaturated

fatty acid

cis double

bond causes

bending

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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

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A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits
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
These trans fats may contribute more than saturated fats to cardiovascular disease

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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

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Phospholipids

In a phospholipid, two fatty acids and a phosphate group are attached to glycerol
The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head

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Fig. 5-13

(b)

Space-filling model

(a)

(c)

Structural formula

Phospholipid symbol

Fatty acids

Hydrophilic

head

Hydrophobic

tails

Choline

Phosphate

Glycerol

Hydrophobic tails

Hydrophilic head

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Fig. 5-13ab

(b)

Space-filling model

(a)

Structural formula

Fatty acids

Choline

Phosphate

Glycerol

Hydrophobic tails

Hydrophilic head

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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

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Fig. 5-14

Hydrophilic

head

Hydrophobic

tail

WATER

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Steroids

Steroids are lipids characterized by a carbon skeleton consisting of four fused rings
Cholesterol, an important steroid, is a component in animal cell membranes
Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease

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Fig. 5-15

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Concept 5.4: Proteins have many structures, resulting in a wide range of functions

Proteins account for more than 50% of the dry mass of most cells
Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances

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Table 5-1

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Animation: Structural Proteins

Animation: Storage Proteins

Animation: Transport Proteins

Animation: Receptor Proteins

Animation: Contractile Proteins

Animation: Defensive Proteins

Animation: Hormonal Proteins

Animation: Sensory Proteins

Animation: Gene Regulatory Proteins

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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

Animation: Enzymes

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Fig. 5-16

Enzyme

(sucrase)

Substrate

(sucrose)

Fructose

Glucose

OH

H

O

H₂O

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Polypeptides

Polypeptides are polymers built from the same set of 20 amino acids
A protein consists of one or more polypeptides

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Amino Acid Monomers

Amino acids are organic molecules with carboxyl and amino groups
Amino acids differ in their properties due to differing side chains, called R groups

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Fig. 5-UN1

Amino

group

Carboxyl

group

 carbon

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Fig. 5-17

Nonpolar

Glycine

(Gly or G)

Alanine

(Ala or A)

Valine

(Val or V)

Leucine

(Leu or L)

Isoleucine

(Ile or I)

Methionine

(Met or M)

Phenylalanine

(Phe or F)

Trypotphan

(Trp or W)

Proline

(Pro or P)

Polar

Serine

(Ser or S)

Threonine

(Thr or T)

Cysteine

(Cys or C)

Tyrosine

(Tyr or Y)

Asparagine

(Asn or N)

Glutamine

(Gln or Q)

Electrically

charged

Acidic

Basic

Aspartic acid

(Asp or D)

Glutamic acid

(Glu or E)

Lysine

(Lys or K)

Arginine

(Arg or R)

Histidine

(His or H)

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Fig. 5-17a

Nonpolar

Glycine

(Gly or G)

Alanine

(Ala or A)

Valine

(Val or V)

Leucine

(Leu or L)

Isoleucine

(Ile or I)

Methionine

(Met or M)

Phenylalanine

(Phe or F)

Tryptophan

(Trp or W)

Proline

(Pro or P)

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Fig. 5-17b

Polar

Asparagine

(Asn or N)

Glutamine

(Gln or Q)

Serine

(Ser or S)

Threonine

(Thr or T)

Cysteine

(Cys or C)

Tyrosine

(Tyr or Y)

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Fig. 5-17c

Acidic

Arginine

(Arg or R)

Histidine

(His or H)

Aspartic acid

(Asp or D)

Glutamic acid

(Glu or E)

Lysine

(Lys or K)

Basic

Electrically

charged

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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

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Peptide

bond

Fig. 5-18

Amino end

(N-terminus)

Peptide

bond

Side chains

Backbone

Carboxyl end

(C-terminus)

(a)

(b)

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Protein Structure and Function

A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape

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Fig. 5-19

A ribbon model of lysozyme

(a)

(b)

A space-filling model of lysozyme

Groove

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Fig. 5-19a

A ribbon model of lysozyme

(a)

Groove

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Fig. 5-19b

(b)

A space-filling model of lysozyme

Groove

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The sequence of amino acids determines a protein’s three-dimensional structure
A protein’s structure determines its function

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Fig. 5-20

Antibody protein

Protein from flu virus

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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

Animation: Protein Structure Introduction

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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

Animation: Primary Protein Structure

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Fig. 5-21

Primary

Structure

Secondary

Structure

Tertiary

Structure

 pleated sheet

Examples of

amino acid

subunits

⁺H₃N

Amino end

 helix

Quaternary

Structure

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Fig. 5-21a

Amino acid

subunits

⁺H₃N

Amino end

25

20

15

10

5

1

Primary Structure

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Fig. 5-21b

Amino acid

subunits

⁺H₃N

Amino end

Carboxyl end

125

120

115

110

105

100

95

90

85

80

75

20

25

15

10

5

1

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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 α helix and a folded structure called a β pleated sheet

Animation: Secondary Protein Structure

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Fig. 5-21c

Secondary Structure

 pleated sheet

Examples of

amino acid

subunits

 helix

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Fig. 5-21d

Abdominal glands of the

spider secrete silk fibers

made of a structural protein

containing  pleated sheets.

The radiating strands, made

of dry silk fibers, maintain

the shape of the web.

The spiral strands (capture

strands) are elastic, stretching

in response to wind, rain,

and the touch of insects.

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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

Animation: Tertiary Protein Structure

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Fig. 5-21e

Tertiary Structure

Quaternary Structure

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Fig. 5-21f

Polypeptide

backbone

Hydrophobic

interactions and

van der Waals

interactions

Disulfide bridge

Ionic bond

Hydrogen

bond

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Fig. 5-21g

Polypeptide

chain

 Chains

Heme

Iron

 Chains

Collagen

Hemoglobin

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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

Animation: Quaternary Protein Structure

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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

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Fig. 5-22

Primary

structure

Secondary

and tertiary

structures

Quaternary

structure

Normal

hemoglobin

(top view)

Primary

structure

Secondary

and tertiary

structures

Quaternary

structure

Function

 subunit

Molecules do

not associate

with one

another; each

carries oxygen.

Red blood

cell shape

Normal red blood

cells are full of

individual

hemoglobin

moledules, each

carrying oxygen.

10 µm

Normal hemoglobin





1

2

3

4

5

6

7

Val

His

Leu

Thr

Pro

Glu

Red blood

cell shape

 subunit

Exposed

hydrophobic

region

Sickle-cell

hemoglobin





Molecules

interact with

one another and

crystallize into

a fiber; capacity

to carry oxygen

is greatly reduced.





Fibers of abnormal

hemoglobin deform

red blood cell into

sickle shape.

10 µm

Sickle-cell hemoglobin

Glu

Pro

Thr

Leu

His

Val

1

2

3

4

5

6

7

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Fig. 5-22a

Primary

structure

Secondary

and tertiary

structures

Function

Quaternary

structure

Molecules do

not associate

with one

another; each

carries oxygen.

Normal

hemoglobin

(top view)

 subunit

Normal hemoglobin

7

6

5

4

3

2

1







Glu

Val

His

Leu

Thr

Pro

Glu

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Fig. 5-22b

Primary

structure

Secondary

and tertiary

structures

Function

Quaternary

structure

Molecules

interact with

one another and

crystallize into

a fiber; capacity

to carry oxygen

is greatly reduced.

Sickle-cell

hemoglobin

 subunit

Sickle-cell hemoglobin

7

6

5

4

3

2

1







Val

His

Leu

Thr

Pro

Glu

Exposed

hydrophobic

region

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Fig. 5-22c

Normal red blood

cells are full of

individual

hemoglobin

molecules, each

carrying oxygen.

Fibers of abnormal

hemoglobin deform

red blood cell into

sickle shape.

10 µm

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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

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Fig. 5-23

Normal protein

Denatured protein

Denaturation

Renaturation

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Protein Folding in the Cell

It is hard to predict a protein’s structure from its primary structure
Most proteins probably go through several states on their way to a stable structure
Chaperonins are protein molecules that assist the proper folding of other proteins

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Fig. 5-24

Hollow

cylinder

Cap

Chaperonin

(fully assembled)

Polypeptide

Steps of Chaperonin

Action:

An unfolded poly-

peptide enters the

cylinder from one end.

1

2

3

The cap attaches, causing the

cylinder to change shape in

such a way that it creates a

hydrophilic environment for

the folding of the polypeptide.

The cap comes

off, and the properly

folded protein is

released.

Correctly

folded

protein

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Fig. 5-24a

Hollow

cylinder

Chaperonin

(fully assembled)

Cap

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Fig. 5-24b

Correctly

folded

protein

Polypeptide

Steps of Chaperonin

Action:

1

2

An unfolded poly-

peptide enters the

cylinder from one end.

The cap attaches, causing the

cylinder to change shape in

such a way that it creates a

hydrophilic environment for

the folding of the polypeptide.

The cap comes

off, and the properly

folded protein is

released.

3

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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

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Fig. 5-25

EXPERIMENT

RESULTS

X-ray

source

X-ray

beam

Diffracted

X-rays

Crystal

Digital detector

X-ray diffraction

pattern

RNA

polymerase II

RNA

DNA

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Fig. 5-25a

Diffracted

X-rays

EXPERIMENT

X-ray

source

X-ray

beam

Crystal

Digital detector

X-ray diffraction

pattern

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Fig. 5-25b

RESULTS

RNA

polymerase II

DNA

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Concept 5.5: Nucleic acids store and transmit hereditary information

The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene
Genes are made of DNA, a nucleic acid

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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 in ribosomes

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Fig. 5-26-1

mRNA

Synthesis of

mRNA in the

nucleus

DNA

NUCLEUS

CYTOPLASM

1

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Fig. 5-26-2

mRNA

Synthesis of

mRNA in the

nucleus

DNA

NUCLEUS

mRNA

CYTOPLASM

Movement of

mRNA into cytoplasm

via nuclear pore

1

2

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Fig. 5-26-3

mRNA

Synthesis of

mRNA in the

nucleus

DNA

NUCLEUS

mRNA

CYTOPLASM

Movement of

mRNA into cytoplasm

via nuclear pore

Ribosome

Amino

acids

Polypeptide

Synthesis

of protein

1

2

3

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The Structure of Nucleic Acids

Nucleic acids are polymers called polynucleotides
Each polynucleotide is made of monomers called nucleotides
Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group
The portion of a nucleotide without the phosphate group is called a nucleoside

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Fig. 5-27

5 end

Nucleoside

Nitrogenous

base

Phosphate

group

Sugar

(pentose)

(b) Nucleotide

(a) Polynucleotide, or nucleic acid

3 end

3C

5C

Nitrogenous bases

Pyrimidines

Cytosine (C)

Thymine (T, in DNA)

Uracil (U, in RNA)

Purines

Adenine (A)

Guanine (G)

Sugars

Deoxyribose (in DNA)

Ribose (in RNA)

(c) Nucleoside components: sugars

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Fig. 5-27ab

5' end

5'C

3'C

5'C

3'C

3' end

(a) Polynucleotide, or nucleic acid

(b) Nucleotide

Nucleoside

Nitrogenous

base

3'C

5'C

Phosphate

group

Sugar

(pentose)

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Fig. 5-27c-1

(c) Nucleoside components: nitrogenous bases

Purines

Guanine (G)

Adenine (A)

Cytosine (C)

Thymine (T, in DNA)

Uracil (U, in RNA)

Nitrogenous bases

Pyrimidines

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Fig. 5-27c-2

Ribose (in RNA)

Deoxyribose (in DNA)

Sugars

(c) Nucleoside components: sugars

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Nucleotide Monomers

Nucleoside = nitrogenous base + sugar
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
Nucleotide = nucleoside + phosphate group

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Nucleotide Polymers

Nucleotide polymers are linked together to build a polynucleotide
Adjacent nucleotides are joined by covalent bonds that form between the –OH group on the 3′ carbon of one nucleotide and the phosphate on the 5′ carbon on the next
These links create a backbone of sugar-phosphate units with nitrogenous bases as appendages
The sequence of bases along a DNA or mRNA polymer is unique for each gene

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The DNA Double Helix

A DNA molecule has two polynucleotides spiraling around an imaginary axis, forming a double helix
In the DNA double helix, the two backbones run in opposite 5′ → 3′ directions from each other, an arrangement referred to as antiparallel
One DNA molecule includes many genes
The nitrogenous bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C)

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Fig. 5-28

Sugar-phosphate

backbones

3' end

5' end

Base pair (joined by

hydrogen bonding)

Old strands

New

strands

Nucleotide

about to be

added to a

new strand

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DNA and Proteins as Tape Measures of Evolution

The linear sequences of nucleotides in DNA molecules are passed from parents to offspring
Two closely related species are more similar in DNA than are more distantly related species
Molecular biology can be used to assess evolutionary kinship

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The Theme of Emergent Properties in the Chemistry of Life: A Review�

Higher levels of organization result in the emergence of new properties
Organization is the key to the chemistry of life

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Fig. 5-UN2

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Fig. 5-UN2a

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Fig. 5-UN2b

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Fig. 5-UN3

% of glycosidic

linkages broken

100

50

0

Time

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Fig. 5-UN4

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Fig. 5-UN5

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Fig. 5-UN6

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Fig. 5-UN7

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Fig. 5-UN8

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Fig. 5-UN9

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Fig. 5-UN10

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You should now be able to:

List and describe the four major classes of molecules
Describe the formation of a glycosidic linkage and distinguish between monosaccharides, disaccharides, and polysaccharides
Distinguish between saturated and unsaturated fats and between cis and trans fat molecules
Describe the four levels of protein structure

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You should now be able to:

Distinguish between the following pairs: pyrimidine and purine, nucleotide and nucleoside, ribose and deoxyribose, the 5′ end and 3′ end of a nucleotide