Chapter 19 Tro Powerpoint

Roy KennedyMassachusetts Bay Community College

Wellesley Hills, MA

Introductory Chemistry, 3rd EditionNivaldo Tro

Chapter 19Biochemistry

2009, Prentice Hall

Tro's Introductory Chemistry, Chapter 19

2

The Cell• Smallest structural unit in a living

organism.• The nucleus is the part of the cell

that controls cell function.• The outer boundary of the cell is

called the cell membrane.• The region between the nucleus and

the cell membrane is called the cytoplasm.The cytoplasm is filled with a number of

specialized structures that carry out much of the cell’s work.


3

Carbohydrates


4

Carbohydrates, Continued• Carbon, hydrogen, and oxygen.• Ratio of H:O = 2:1.

Same as in water.

• Contain carbonyl groups and alcohol groups.Large number of polar groups leads to high solubility in

water.Dissolve in blood stream.

• Also known as sugars, starches, cellulose, dextrins, and gums.

5

Classification of Carbohydrates• Hydroxycarbonyls have many OHs and one C=O.• Names of monosaccharides and disaccharides all end in –ose.

• Monosaccharides cannot be broken down into simpler carbohydrates.Triose, tetrose, pentose, and hexose.Aldose contain aldehyde carbonyl.Ketose contain ketone carbonyl.

• Disaccharides are two monosaccharides linked.Lose H from one and OH from other.

• Polysaccharides are three or more monosaccharides linked into complex chains.Starch and cellulose polysaccharides of glucose.


6

Carbohydrate Formula Source

Glucose (mono) C6H12O6 Blood, plants, fruit, honey

Fructose (mono) C6H12O6 Plants, fruit, honey

Galactose (mono) C6H12O6

Sucrose (disac) C12H22O11 Sugar cane and beets, maple

syrup, fruits and veggies

Maltose (disac) C12H22O11 Partial hydrolysis of starch

Lactose (disac) C12H22O11 Milk (5%)

Starch (poly) Potatoes, corn, grains

Cellulose (poly) Cell wall of plants

Saccharides


7

D-Glyceraldehyde

OH

C

C

C

C

O

HH H

H

OH

OHH

C HOH

COH H

CH2OH

CHOD-Erythrose

OH

C

C

C

C

O

HH OH

H

H

OHH

C OHH

COH H

CH2OH

CHOD-Threose

C OHH

CH2OH

CHO

HOCH2

C

C

O

H OH

H

8

C

C

C

C

C

OOH

H

H H

H

OH

H

OH

OH H

C

C

C

CH2OH

CHO

OH

OH

OHH

H

H

D-Ribose D-Arabinose

C

C

C

C

C

OOH

H

H OH

H

OH

H

H

OH H

C

C

C

CH2OH

CHO

H

OH

OHH

H

OH

C

C

C

C

C

OOH

H

H OH

H

OH

OH

H

H H

C

C

C

CH2OH

CHO

H

H

OHH

OH

OH

D-Lyxose

C

C

C

C

C

OOH

H

H H

H

OH

OH

OH

H H

C

C

C

CH2OH

CHO

OH

H

OHH

OH

H

D-Xylose

Ald

open

tose

s


9

Ring Structure• In aqueous solution, monosaccharides exist

mainly in the ring form.

C

C

C

C

C

OOH

H

H H

H

OH

H

OH

OH H

OH

OHOH

O

OH CH

CHCH

CHC

H2

Ribose

OH

C

C

C

C

C

CO

H

H

H

OH OHH H H

H OHOH

OH

OHOH

OH

O

OH

CH

CHCH

CH

CH

CH

2

Glucose


10

Cyclic Monosaccharides• Oxygen attached to second last carbon

bonds to carbonyl carbon.Acetal formation.

• Convert carbonyl to OH.Transfer H from original O to carbonyl O.

• New OH group may be same side as CH2OH () or opposite side ().

• Haworth projection.

11

Formation of Ring Structure


12

Glucose• A.k.a. blood sugar, grape

sugar, and dextrose.

• Aldohexose = sugar containing aldehyde group and six carbons.

• Source of energy for cells.5 to 6 grams in blood stream.Supplies energy for about 15

minutes.

C

C C

C

OC OH

HH

OH

OH

H

H

OH H

CH2OH

CH2OHC

C

C

CC

O

OH

OH

OH

OH

H

H

H

HH


13

Fructose• A.k.a. levulose, fruit

sugar.

• Ketohexose = sugar containing ketone group and six carbons.

• Sweetest known natural sugar.

C

C C

C

O

H

OH

OH

H

OH

CH2OHH

HOH2C

CC

CC

CH2OH

O

OH

OH

OHH H

H

HOH2C


Galactose

• Occurs in brain and nervous system.

• Only difference between glucose and galactose is spatial orientation of groups on C4.

Glucose

OH

OH

OH

OH

O

OH CH

CHC

HCH

CHC

H2

HOCH2

CC

CC

CO

OH H

H

H

OH

OH

OH H H


15

Disaccharides

• Disaccharides are two monosaccharides linked together.

• When monosaccharides react together, a molecule of water is released.

• The bond between the monosaccharide units is called a glycosidic link.


16

Sucrose


17

Sucrose, Continued

• Also known as table sugar, cane sugar, beet sugar.

• Glucose + fructose = sucrose. —1:2-linkage involves

aldehyde group from glucose and ketone group from fructose. Gyclosidic link.

• Nonreducing sugar.Negative Benedict’s test.


18

O

C

CC

C

C

CH2OH

H

OH

OH

H

OH

HH

OH C C

C

O

C

HOCH2

OH

H

OH

OH

H

OH

CH2OHC

3C

4

C5

O

C2

HOCH2

1

H

OH

OH

H

OH

CH2OH6

O

C1

C 2C 3

C4

CH

5

CH2OH6

H

OH

OH

H

O

HH

OH

Sucrose, Continued

Glucose Fructose

– 1:2 Glycosidic Linkage

19

Lactose• Milk sugar.

• Glucose + galactose. -glycosidic linkage.

• Reducing sugar.Gives positive Benedict’s test.

O

C

CC

C

C

CH2OH

H

OH

OH

H

H

OH

H

O

C

CC

C

C

CH2OH

H

OH

OH

H

OH

HH

O

Galactose

Glucose

-1:4 glycosidic link

Digestion and Hydrolysis• Digestion breaks polysaccharides and

disaccharides into monosaccharides.• Hydrolysis is the addition of water to break the

glycosidic link.Under acidic or basic conditions.

• Monosaccharides can pass through intestinal walls into the blood stream.


21

Simple or Complex

• Monosaccharides and disaccharides are called simple sugars because they contain only two saccharide units.Also known as simple carbohydrates.

• Polysaccharides are called complex sugars because they are polymers of many saccharide units linked in chains.


22

Polysaccharides—Starch and Cellulose• Both are made of glucose rings linked together in long

chains. The only difference is the way the rings are linked.Give only glucose on hydrolysis.The differences in the way the rings are linked results in the

different properties of starch and cellulose.• Starch.

Digestible, soft, and chewy. 1:4— link.

• Cellulose. Not digestible. Fibrous, plant structural material.1:4—link.

• Glycogen. Structure similar to glucose, except highly branched.Used for excess glucose storage in animal bloodstreams.


23

and Glycosidic Links


24

Starch

—1:4 linkage

25

Practice—Which of the Following Molecules Are Carbohydrates?

OOH

H

OH

HOH2C

H

CH2OH

OH

H

O

H

OH

OH

H

H

CH2OH

HOH2C

OO

HH

OH

OH

H

H

OH H

CH2OHCH2

CH

CH2

OH

OH

OH

CH2OH

C

C

C

C

HOH2C

O

H

H

H

OH

OH

OH

NH2

CH C

NH

CH C

NH

CH C

O

O

CH3 O

OH

CH

CH3CH3

CH2SH

O

CCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

C

OCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH

C

O

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

Practice—Which of the Following Molecules Are Carbohydrates?, Continued

OOH

H

OH

HOH2C

H

CH2OH

OH

H

O

H

OH

OH

H

H

CH2OH

HOH2C

OO

HH

OH

OH

H

H

OH H

CH2OHCH2

CH

CH2

OH

OH

OH

CH2OH

C

C

C

C

HOH2C

O

H

H

H

OH

OH

OH

NH2

CH C

NH

CH C

NH

CH C

O

O

CH3 O

OH

CH

CH3CH3

CH2SH

O

CCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

C

OCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH

C

O

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

Carbohydrates have multiple OH groups and either C=O or two Os attached to the same C.


27

Lipids


28

Lipids, Continued• Chemicals of the cell that are insoluble in water,

but soluble in nonpolar solvents.• Fatty acids, fats, oils, phospholipids, glycolipids,

some vitamins, steroids, and waxes.• Structural components of cell membrane.

Because they don’t dissolve in water.

• Long-term energy storage.• Insulation.


29

Fatty Acids• Carboxylic acid (head) with a very long

hydrocarbon side chain (tail).• Saturated fatty acids contain no C=C double bonds

in the hydrocarbon side chain.• Unsaturated fatty acids have C=C double bonds.

Monounsaturated have one C=C. Polyunsaturated have more than one C=C.

CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 C

O

OH

HeadTail


30

Fatty Acids, ContinuedStearic acid—C18H36O2 a saturated fatty acid.

CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 C

O

OHCH2CH2CH2CH2CH2CH3

Oleic acid—C18H36O2 a monounsaturated fatty acid.

CH2 CH2 CH CH CH2 CH2 CH2 CH2 CH2 CH2 CH2 C

O

OHCH2CH2CH2CH2CH2CH3

31

Fatty Acids, Continued

32

Fats and Oils: Triglycerides• Fats are solid at room

temperature; oils are liquids.• Trigylcerides are triesters of

glycerol with fatty acids. The bonds that join glycerol to the

fatty acids are called ester linkages.

Glycerol

CH2

CH2

CH2

OH

OH

OH

CH2

CH2

CH2

O

O

O

C

C

C

O

O

O

CH2

CH2

CH2

CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2



CH3

CH3

CH3

ester linkage

33

Tristearin

34

Practice—Which of the Following Molecules Are Triglycerides? Classify as Saturated or Unsaturated.

OOH

H

OH

HOH2C

H

CH2OH

OH

H

O

H

OH

OH

H

H

CH2OH

HOH2C

OO

HH

OH

OH

H

H

OH H

CH2OHCH2

CH

CH2

OH

OH

OH

CH2OH

C

C

C

C

HOH2C

O

H

H

H

OH

OH

OH

NH2

CH C

NH

CH C

NH

CH C

O

O

CH3 O

OH

CH

CH3CH3

CH2SH

O

CCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

C

OCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH

C

O

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

35

Practice—Which of the Following Molecules Are Triglycerides? Classify as Saturated or Unsaturated, Continued.

OOH

H

OH

HOH2C

H

CH2OH

OH

H

O

H

OH

OH

H

H

CH2OH

HOH2C

OO

HH

OH

OH

H

H

OH H

CH2OHCH2

CH

CH2

OH

OH

OH

CH2OH

C

C

C

C

HOH2C

O

H

H

H

OH

OH

OH

NH2

CH C

NH

CH C

NH

CH C

O

O

CH3 O

OH

CH

CH3CH3

CH2SH

O

CCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

C

OCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH

C

O

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3OCH2

Saturated


36

Triglycerides• Triglycerides differ in the length of the fatty acid

side chains and in the degree of unsaturation.Side chains range from 12 to 20 C.Most natural triglycerides have different fatty acid chains

in the triglyceride; simple triglycerides have three identical chains.

• Saturated fat = all saturated fatty acid chains.Warm-blooded animal fat.Solids.

• Unsaturated fats = some unsaturated fatty acid chains.Cold-blooded animal fat or vegetable oils.Liquids.


37

Tristearin: A Simple Triglyceride Found in

Lard


38

Triolein:A Simple Triglyceride Found in Olive Oil


39

Structure and Melting Point

Name MP °C

Class

Myristic acid 58 Sat., 14 C

Palmitic acid 63 Sat, 16 C

Stearic acid 71 Sat, 18 C

Oleic acid 16 1 DB, 18 C

Linoleic acid -5 2 DB, 18 C

Linolenic acid -11 3 DB, 18 C

• Larger fatty acid = higher melting point.

• Double bonds decrease the melting point.More DB = lower MP.

• Saturated = no DB.• Monounsaturated = 1 DB.• Polyunsaturated = many

DB.


40

Cis Fats and Trans Fats

• Naturally unsaturated fatty acids contain cis double bonds.

• Processed fats come from polyunsaturated fats that have been partially hydrogenated, resulting in trans double bonds.

• Trans fats seem to increase the risk of coronary disease.


41

Practice—Would the Following Triglyceride Be Most Likely Found in Lard or Vegetable Oil?

CH2

CH2

CH2

CH2

CH3

OC

CH2

CH2

CH2

CH2

CH2

CH

CH

CH2

O

CH2

CH2

CH2

CH

OC

CH2

CH2

CH2

CH2

CH2

CH

CH

CH2

O

CH

CH3CH

CH2

CH2

CH

OC

CH2

CH2

CH2

CH2

CH2

CH

CH

CH2

O

CH

CH3CH2


42

Practice—Would the Following Triglyceride Be Most Likely Found in Lard or Vegetable Oil?,

Continued

CH2

CH2

CH2

CH2

CH3

OC

CH2

CH2

CH2

CH2

CH2

CH

CH

CH2

O

CH2

CH2

CH2

CH

OC

CH2

CH2

CH2

CH2

CH2

CH

CH

CH2

O

CH

CH3CH

CH2

CH2

CH

OC C

H2CH2

CH

CH

CH2

O

CH

CH3CH2

Many unsaturations, vegetable oil


45

Soaps• Triglycerides can be broken down into fatty acid salts and

glycerol by treatment with a strong hydroxide solution. The reaction is called saponifcation.

• Fatty acid salts have a very polar “head” because it is ionic and a very non-polar “tail” because it is all C and H.Hydrophilic head and hydrophobic tail.

• This unique structure allows the fatty acid salts, called soaps, to help oily substances be attracted to water. Micelle formation.

Emulsification.


46

Micelle

Oily particle

Hydrophilic head

Hydrophobic tail


47

Phospholipids• Esters of glycerol.• Glycerol attached to two fatty

acids and one phosphate group.• Phospholipids have hydrophilic

heads due to phosphate group, and hydrophobic tails from the fatty acid hydrocarbon chain.

• Part of lipid bilayer found in animal cell membranes.


48

Lipid Bilayer


49

Steroids• Characterized by four linked carbon

rings.• Mostly hydrocarbon-like.

Dissolve in animal fat.• Mostly have hormonal effects.• Serum cholesterol levels linked to

heart disease and stroke.Levels depend on diet, exercise,

emotional stress, genetics, etc.• Cholesterol synthesized in the liver

from saturated fats.

C

CC

CC

CC

C

CC

CC C

CC

C

C


50

Steroids, Continued

cholesterol

HO

CH3

CH3

CH3

CH3

CH3

O

CH3

CH3OHtestosterone

HO

CH3OH

estrogen-estradiol

O

CH3

CH3 O

OCH3C

progesterone


51

Practice—Which of the Hormones on the Previous Slide Does the Synthetic Hormone Below Mimic?

CH3O

CH3

OH

C CH


52

Practice—Which of the Hormones on the Previous Slide Does the Synthetic Hormone Below Mimic?,

Continued

CH3O

CH3

OH

C CH

Mestranol—a synthetic estrogen.


53

Proteinsand

Amino Acids


54

Proteins• Involved in practically all facets of cell function.• Polymers of amino acids.


55

Protein Structure• Proteins are polymers of amino acids.• The structure of a protein is key to its function.• Enzymes are proteins that act as catalysts.• Most proteins are classified as either fibrous or globular.• Fibrous proteins have linear, simple structure.

Insoluble in water.Used in structural features of the cell.

• Globular proteins have complex, three-dimensional structure.Generally have polar R groups of the amino acids pointing

out, so they are somewhat soluble, but also maintain an area that is nonpolar in the interior.

Fibrous & Globular Proteins


57

Amino Acids• NH2 group on carbon adjacent to COOH.

-amino acids.• About 20 amino acids found in proteins.

10 synthesized by humans, 10 “essential.”• Each amino acid has three-letter abbreviation.

Glycine = Gly.• High melting points.

Generally decompose at temperature > 200 °C.• Good solubility in water.• Less acidic than most carboxylic acids and less

basic than most amines.


58

Basic Structure of Amino Acids


59

Amino Acids• Main difference between amino acids is the side chain.

R group.

• Some R groups are polar, others are nonpolar.• Some polar R groups are acidic, others are basic.• Some R groups contain O, others N and others S.• Some R groups are rings, others are chains. • The differences in the R groups give the amino acids

their different properties.


Amino Acid Sidechains

61

Amino Acid Sidechains, Continued


62

NH2

CH C

O

CH3

OH NH2

CH C

O

CH2

CH2

CH2

NH

C

NH

NH2 OH

NH2

CH

O

CH2

CO

NH2

OH

NH2

CH

O

CH2

CO

OH

OH

AlanineAla

ArginineArg

AsparagineAsn

Aspartic AcidAsp


63

NH2

CH C

O

CH2

SH OH

NH2

CH C

O

CH2

CH2

C

O

NH2 OH

NH2

CH2C

O

OH

NH2

CH C

O

CH2

CH2

C

O

OH OH

CysteineCys

GlutamineGln

GlycineGly

Glutamic AcidGlu


64

NH2

CH C

O

CH2

CN

CHCH

NH

OH

NH2

CHC

HCH2

O

CCH3

CH3

OH

NH2

CHC

H2

CH

O

CCH3

CH3

OH

NH2

CH C

O

CH2

CH2

CH2

CH2

NH2OH

HistidineHis

IsoleucineIle

LeucineLeu

LysineLys


65

NH

CH

CH2

CH2

CH2

C

O

OH

NH2

CHC

H2

OH

O

COH

NH2

CH C

O

CH2

CH2

S

CH3 OH

NH2

CHC

H2 O

CC

CHCH

CH

CHCH

OH

ProlinePro

SerineSer

MethionineMet

PhenylalaninePhe


66

CHC

H C

NH2

CH3

OH O

OHNH2

CHC

H2O

CCC

CHC

NH

CH

CH

CH

CH

OH

NH2

CHC

H2 O

CC

CHCH

C

CHCH

OH

OH

NH2

CHC

HCH3

O

C

CH3

OH

ThreonineThr

TryptophanTrp

TyrosineTyr

ValineVal

67

Practice—Classify the R Group of Each Amino Acid as Acidic, Basic, Polar, or

Nonpolar.

NH2

CC

O

CH

2

CH2

C

O

OH

OH

H NH2

CCH

2

CH

O

CCH3

CH3

OH

H

NH2

CC

O

CH

2

CN

CHCH

NH

OH

HNH2

C

CH

2O

C

OHH

OH

68

Practice—Classify the R Group of Each Amino Acid as Acidic, Basic, Polar, or

Nonpolar, Continued.

NH2

CC

O

CH

2

CH2

C

O

OH

OH

H NH2

CCH

2

CH

O

CCH3

CH3

OH

H

NH2

CC

O

CH

2

CN

CHCH

NH

OH

HNH2

C

CH

2O

C

OHH

OH

Acidic Nonpolar

PolarBasic


6969


70

Primary Protein Structure• The primary structure is determined by the order of

amino acids in the polypeptide.

• Link COOH group of first to NH2 of second.Loss of water, condensation.Form an amide structure.Peptide bond.

• Linked amino acids are called peptides.Dipeptide = 2 amino acids, tripeptide = 3, etc.Polypeptides = many linked amino acids in a long chain.

• Changing one amino acid in the chain can alter the biochemical behavior of the protein.


71

Peptide Bond Formation


72

Practice—Draw the Structure of the Tripeptide Glu-Leu-His (Where Glu Is on the

C-Terminus).


73

Practice—Draw the Structure of the Tripeptide Glu-Leu-His (Where Glu Is on the

C-Terminus), Continued.

NH

CH

COH

CH2

CH2

CO

OH

O

NH

CH

CH2

CH

C

CH3

CH3

O

NH2CH

C

O

CH2

C

NCH

CH

NH


74

Primary StructureSickle-Cell Anemia

• Changing one amino acid in the protein can vastly alter the biochemical behavior.

• Sickle-cell anemia. Replace one Val amino acid with Glu on two of the four

chains.Red blood cells take on sickle shape that can damage organs.


75

Secondary Structure

• Short range repeating patterns found in protein chains.

• Maintained by interactions between amino acids that are near each other in the chain.

• Formed and held by H bonds between NH and C=O. -helix.

Most common. -pleated sheet.• Many proteins have sections that are -helix, other

sections are -sheets, and others are random coils.


76

-Helix

• Amino acid chain wrapped in a tight coil with the R groups pointing outward from the coil.

• The pitch is the distance between the coils.

• The pitch and helix diameter ensure bond angles are not strained and H bonds are as strong as possible.


77

-Helix, Continued


78

-Pleated Sheet

• Extended chain forms a zig-zag pattern.

• Chains linked together by H bonds.

• Silk.

79

Practice—The Amino Acids Shown Are on Two Different Peptide Strands that Show -Pleated Sheet Secondary Structure. Show the

H-Bonds that Form Between Them with Dashed “Bonds.”

N

CH

C

CH2

CH2

CO

OH

O

N

CH

CH2

CH

C

CH3

CH3

O

N

CH

C

O

CH2

C

NCH

CH

NH

H H H

N

CH

C

CH2

CH2

C O

OH

O

N

CH

CH2

CH

C

CH3CH3

O

N

CH

C

O

CH2

C

NCH

CH

NH

HHH

80

Practice—The Amino Acids Shown Are on Two Different Peptide Strands that Show -Pleated Sheet Secondary Structure. Show the

H-Bonds that Form Between Them with Dashed “Bonds,” Continued.

N

CH

C

CH2

CH2

CO

OH

O

N

CH

CH2

CH

C

CH3

CH3

O

N

CH

C

O

CH2

C

NCH

CH

NH

H H H

N

CH

C

CH2

CH2

C O

OH

O

N

CH

CH2

CH

C

CH3CH3

O

N

CH

C

O

CH2

C

NCH

CH

NH

HHH


81

Tertiary Structure• Large-scale bends and folds due to interactions

between R groups separated by large distances on the chains.

• Types of interactions include:H bonds.Disulfide linkages.

Between cysteine amino acids.Hydrophobic interactions.

Between large, nonpolar R groups.Salt bridges.

Between acidic and basic R groups.


82

Cysteine• The amino acid cysteine performs a

unique function in protein structure.• Cysteine units on remote parts of the

peptide chain can react together, forming a disulfide bond.

• The disulfide bond ties parts of the chain together, contributing to the tertiary structure.

C

C

NH2

O

OH

HCH

2SH


83

Interactions that Create Tertiary Structure


84

Tertiary Structure and Protein Type

• Fibrous proteins generally lack tertiary structure.Extend as long, straight chains with some secondary

structure.Generally are the structural proteins.

• Globular proteins fold in on themselves, forming complex shapes due to the tertiary interactions.Generally function as nonstructural proteins such as

enzymes.


85

Types of Proteins

• Tertiary structure determines the type of protein.• Globular:

Folds into a fairly compact, spherical shape.Water soluble.Mobile.

• Fibrous:Long coils aligned in stacks like pipes.Water insoluble.Provides strength to tissues.

Fibrous & Globular Proteins


87

Quaternary Structure• Many proteins are composed of multiple amino

acid chains.• The way the chains are linked together is called

quaternary structure.• Interactions between chains are the same as in

tertiary structure.


88

Nucleic Acids


89

Nucleic Acids, Continued• Carry genetic information.• DNA molar mass = 6 to 16 million amu.• RNA molar mass = 20K to 40K amu.• Made of nucleotides.

Phosphoric acid unit.Five carbon sugar.Cyclic amine (base).

• Nucleotide joined by phosphate linkages.


90

Nucleotide Structure• Each nucleotide has three parts: a cyclic pentose, a phosphate

group, and an organic aromatic base.• The pentoses are ribose or deoxyribose.• The pentoses are the central backbone of the nucleotide.• The pentose is attached to the organic base at C1 and to the

phosphate group at C5.

O

HH

H

H

OH

H

CH2

PO

OH

OH

O N

NO NH2


91

Sugars

C

C C

C

O

OH

H

OH

H

OH

HH

HOH2CC

C C

C

O

H

H

OH

H

OH

HH

HOH2C

Deoxyribose Ribose


92

Bases• The bases are organic amines that are aromatic.

Like benzene, except containing N in the ring.Means the rings are flat rather than puckered like the sugar rings.

• Two general structures: two of the bases are similar in structure to the organic base purine; the other two bases are similar in structure to the organic base pyrimidine.


93

Organic Bases

NH

CNH

CH

CHC

O

O

NH

CNH

CH

CC

O

O

CH3N

CNH

CH

CHC

NH2

O

N

CHN

C

NH2

NC

C NH

CHN

CN

C

OH

NC

C NH

CH

NH2

UracilThymineCytosine

Adenine Guanine

Purines

Pyrimidines


94

Bases• The structures of the base are complementary,

meaning that a purine and pyrimidine will precisely align to H-bond with each other.Adenine matches thymine or uracil.Guanine matches cytosine.

PurineBases

PyrimidineBases


95

DNA• Deoxyribonucleic acid.• Sugar is deoxyribose.• One of the following amine bases:

Adenine (A).Guanine (G).Cytosine (C).Thymine (T).

• Two DNA strands wound together in double helix.

• Each cell has entire DNA structure.


96

RNA• Ribonucleic acid.• Sugar is ribose.• One of the following amine bases:

Adenine (A).Guanine (G).Cytosine (C).Uracil (U).

• Single strands wound in helix.


97

Nucleotide FormationO

H

H

OH

H

OH

HH

HOH2C

N

N

NH2

N

NH O

H

H

OH

HHH

HOH2C

N

N

NH2

N

N+ H2O

+

O

H

H

OH

HHH

HOH2C

N

N

NH2

N

N

+ H2OOH P OH

OH

O

+OH P O

OH

O

O

H

H

OH

HHH

N

N

NH2

N

NCH2


98

NCH C

CH

CH

O C

N

N

CH

OH

CH

C

CHOH

CH2

N

NH2

O

P OOH

OH

Practice—Would the Nucleotide Shown Below Be Found in DNA or RNA? Is the Base a Purine or

Pyrimidine? What Is the Name of the Base?


99

Practice—Would the Nucleotide Shown Below Be Found in DNA or RNA? Is the Base a Purine or

Pyrimidine? What Is the Name of the Base?, Continued

NCH C

CH

CH

O C

N

N

CH

OH

CH

C

CHOH

CH2

N

NH2

O

P OOH

OH

RiboseRNA

Adenine,a purine.


100

Primary Structure of Nucleic Acids

• Nucleotides are linked together by attaching the phosphate group of one to the sugar of another at the O of C3.

• The attachment is called a phosphate ester bond.

• The phosphate group attaches to C3 of the sugar on the next nucleotide.

CH3

CH2

C1

O

C4

Base

H

HOH

H

CH25

OPO

O

O

CH3

CH2

C1

O

C4

Base

H

HOH

H

CH25

OPO

O

O

CH

3

CH2

C1

O

C4

Base

H

HO

H

CH25

OPO

O

O

CH3

CH2

C1

O

C4

Base

H

HOH

H

CH25

OPO

O


101

Linking Nucleotides

O

HH

H

H

OH

H

CH2

PO

OH

OH

O N

NO NH2

O

HH

H

H

OH

H

CH2

PO

OH

OH

O N

NO NH2

+

O

HH

H

HH

CH2

PO

OH

OH

O N

NO NH2

O

HH

H

H

OH

H

CH2

O

PO OH

O N

NO NH2

+ H2O


102

Nucleotide Chain


103

Practice—Draw a Linked Pair of Nucleotides Having Cytosine and Thymine as the Bases.


104

Practice—Draw a Linked Pair of Nucleotides Having Cytosine and Thymine as the Bases,

Continued.

O

CH CH2

C C

O

O

N

CNH

C

CCH

O

O

CH3P OHOH

O

OH

CH CH2

C C

OCH2

O

N

CN

CH

CH NH2

OHH

P OHO

HH


105

DNA Structure

• DNA made of two strands linked together by H bonds between bases.

• Bases are complementary.A pairs with T, C

with G.


106

Base Pairing

N

NH

CH

O

O

CH3

HN

N

N N

NHH

H AdenineThymine• Base pairing generates

the helical structure.• In DNA, the two

strands have complementary bases.Hold strands

together.Allow replication

of strand.


107

Adenine–Thymine Base Pair


108

DNA Replication

• When the DNA is to be replicated, the region to be replicated uncoils.

• This H bond between the base pairs is broken, separating the two strands.

• With the aid of enzymes, new strands of DNA are constructed by linking the complementary nucleotides to the original strand together.


109

DNA Replication, Continued


110

DNA Replication, Continued

111

Nucleic Acid → Polypeptide• Nucleic acids code for the production of proteins.• The order of bases in the nucleic acid determines the

order of amino acids in the polypeptide.• Three nucleic acids are required to code for each amino

acid.Codon.The three nucleotide sequences that code for a particular amino

acid are the same in all living organisms.

• A gene is a set of codons that code for a single protein.


112

Protein Synthesis• Transcription → translation.• In nucleus, DNA strand at gene separates and a

complementary copy of the gene is made in RNA.Messenger RNA = mRNA.

• The mRNA travels into the cytoplasm where it links with a ribosome.

• At the ribosome, each codon on the RNA codes for a single amino acid. They are joined together to form the polypeptide chain.


113

Protein Synthesis, Continued


114

Organization of Genetic Material

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