Macromolecules

Chapter 5

Macromolecules

Large complex molecules Carbohydrates, proteins, lipids &

nucleic acids

Macromolecules

Polymer Large molecule Carboydrates, proteins, nucleic

acids Monomers Smaller repeating units Build polymers

Macromolecules

Monomers are connected by a dehydration reaction

Condensation reaction

Fig. 5-2a

Dehydration removes a watermolecule, forming a new bond

Short polymer Unlinked monomer

Longer polymer

Dehydration reaction in the synthesis of a polymer

HO

HO

HO

H2O

H

HH

4321

1 2 3

(a)

Macromolecules

Polymers are broken apart into monomers by hydrolysis

Bonds are broken by adding water

Fig. 5-2b

Hydrolysis adds a watermolecule, breaking a bond

Hydrolysis of a polymer

HO

HO HO

H2O

H

H

H321

1 2 3 4

(b)

Carbohydrates

Simple sugars to complex polymers

Stored energy Structure

Carbohydrates

Monosaccharides Single sugar

– Glucose, fructose, galactose Molecules contain carbon, hydrogen &

oxygen in a 1:2:1 ratio CH2O End in –ose Aldose: aldehyde sugar Ketose: ketone sugar

Fig. 5-3a

Ald

ose

s

Glyceraldehyde

Ribose

Glucose Galactose

Hexoses (C6H12O6)Pentoses (C5H10O5)Trioses (C3H6O3)

Fig. 5-3b

Ket

ose

s

Dihydroxyacetone

Ribulose

Fructose

Hexoses (C6H12O6)Pentoses (C5H10O5)Trioses (C3H6O3)

Carbohydrates

Dissaccharides Two monosaccharides combined Glycoside linkage: Covalent bond between two sugars Sucrose (glucose & fructose) Maltose (glucose & glucose) Lactose (glucose & galactose)

Fig. 5-5

(b) Dehydration reaction in the synthesis of sucrose

Glucose Fructose Sucrose

MaltoseGlucoseGlucose

(a) Dehydration reaction in the synthesis of maltose

1–4glycosidic

linkage

1–2glycosidic

linkage

Carbohydrates

Polysaccharides Many monosaccharides combined Starch (plant), glycogen (animal),

cellulose (plant), chitin

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

Fig. 5-10

The structureof the chitinmonomer.

(a) (b) (c)Chitin forms theexoskeleton ofarthropods.

Chitin is used to makea strong and flexiblesurgical thread.

Lipids

Insoluble in water– Hydrophobic

Store energy Make membranes

Lipids

Fats– Unsaturated– Saturated

Phospholipids– Glycerol, phosphate, fatty acid

Steroids

Fats

Glycerol and fatty acids Triglyceride 3 fatty acids attached to a glycerol

Fatty acid(palmitic acid)

(a) Dehydration reaction in the synthesis of a fat

Glycerol

Fig. 5-11b

(b) Fat molecule (triacylglycerol)

Ester linkage

Fig. 5-12

Structuralformula of asaturated fatmolecule

Stearic acid, asaturated fattyacid

(a) Saturated fat

Structural formulaof an unsaturatedfat molecule

Oleic acid, anunsaturatedfatty acid

(b) Unsaturated fat

cis doublebond causesbending

Phospholipids

Cell membrane Tails are hydrophobic Hydrophilic head

Fig. 5-14

Hydrophilichead

Hydrophobictail WATER

WATER

Steroids

Steroids

Proteins

Amino acids Building blocks of proteins 20 different amino acids Peptide bond Polypeptide

Peptidebond

Fig. 5-18

Amino end(N-terminus)

Peptidebond

Side chains

Backbone

Carboxyl end(C-terminus)

(a)

(b)

Fig. 5-17Nonpolar

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)

Electricallycharged

Acidic Basic

Aspartic acid(Asp or D)

Glutamic acid(Glu or E)

Lysine(Lys or K)

Arginine(Arg or R)

Histidine(His or H)

Protein Function

Enzyme catalysis Defense Transport Support Motion Regulation Storage

Protein structure

Primary Secondary Tertiary Quaternary

Primary Structure

Sequence of amino acids

Secondary Structure

Hydrogen bonds between amino acids

Pleats or helix

Tertiary structure

Attraction between side chains Hydrophobic interaction Disulfide bridges Ionic bonds Hydrogen bonds

Quaternary structure

Two or more polypeptide chains aggregate

Sickle cell anemia

Fig. 5-22

Primarystructure

Secondaryand tertiarystructures

Quaternarystructure

Normalhemoglobin(top view)

Primarystructure

Secondaryand tertiarystructures

Quaternarystructure

Function Function

subunit

Molecules donot associatewith oneanother; eachcarries oxygen.

Red bloodcell shape

Normal red bloodcells are full ofindividualhemoglobinmoledules, eachcarrying oxygen.

10 µm

Normal hemoglobin

1 2 3 4 5 6 7

Val His Leu Thr Pro Glu Glu

Red bloodcell shape

subunit

Exposedhydrophobicregion

Sickle-cellhemoglobin

Moleculesinteract withone another andcrystallize intoa fiber; capacityto carry oxygenis greatly reduced.

Fibers of abnormalhemoglobin deformred blood cell intosickle shape.

10 µm

Sickle-cell hemoglobin

GluProThrLeuHisVal Val

1 2 3 4 5 6 7

Structure

Denaturation: Alter, unravel shape of protein Temperature, pH, salt Chaperonins: Proteins that help with structure

Nucleic Acids

DNA and RNA Transfer & store genetic

information Nucleotides are the subunits Nitrogenous base 5 carbon sugar Phosphate group

Nucleic Acids

Pyrimidines Cytosine, thymine and uracil Single carbon ring Purines Adenine, guanine Double ring structure

Nitrogenous Bases

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

Fig. 5-27c-2

Ribose (in RNA)Deoxyribose (in DNA)

Sugars

(c) Nucleoside components: sugars

DNA

Double helix Sugar-phosphate backbone is on the

outside of helix Run in opposite direction Antiparallel Base pairs held together by hydrogen

bonds Adenine-thymine (uracil) Cytosine-guanine

DNA

DNA

Fig. 5-28

Sugar-phosphatebackbones

3' end

3' end

3' end

3' end

5' end

5' end

5' end

5' end

Base pair (joined byhydrogen bonding)

Old strands

Newstrands

Nucleotideabout to beadded to anew strand