AP Biology

Macromolecules

You are what you eat!

AP Biology

Polymer

Is a long molecule consisting of many similar building blocks called monomers

Specific monomers make up each macromolecule

E.g. amino acids are the monomers for proteins

2

AP Biology 3

The Synthesis and Breakdown of Polymers Monomers form larger molecules by

condensation reactions called dehydration synthesis

(a) Dehydration reaction in the synthesis of a polymer

HO H1 2 3 HO

HO H1 2 3 4

H

H2O

Short polymer Unlinked monomer

Longer polymer

Dehydration removes a watermolecule, forming a new bond

Figure 5.2A

AP Biology 4

The Synthesis and Breakdown of Polymers Polymers can disassemble by

Hydrolysis (addition of water molecules)

(b) Hydrolysis of a polymer

HO 1 2 3 H

HO H1 2 3 4

H2O

HHO

Hydrolysis adds a watermolecule, breaking a bond

Figure 5.2B

AP Biology

Carbohydrates Structure / monomer

monosaccharide Function

energy raw materials energy storage structural compounds

Examples glucose, starch, cellulose, glycogen

glycosidic bond

AP Biology

Sugars Most names for sugars end in -ose Classified by number of carbons

6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde)

OH

OH

H

H

HO

CH2OH

HH

H

OH

O

Glucose

H

OH

HO

O H

HHO

H

Ribose

CH2OH

Glyceraldehyde

H

H

H

H

OH

OH

O

C

C

C6 5 3

AP Biology

Bonding of Carbohydrates

DisaccharidesConsist of

monosaccharidesAre joined by a

glycosidic linkage

7

AP Biology

Simple & complex sugars Monosaccharides

simple 1 monomer sugars glucose

Disaccharides 2 monomers sucrose

Polysaccharides large polymers starch

OH

OH

H

H

HO

CH2OH

H

H

H

OH

O

Glucose

AP Biology

Polysaccharides Polymers of sugars

costs little energy to build easily reversible = release energy

Function: energy storage

starch (plants) glycogen (animals)

in liver & muscles structure

cellulose (plants) chitin (arthropods & fungi)

AP Biology

Polysaccharide diversity Molecular structure determines function

isomers of glucose structure determines function…

in starch in cellulose

AP Biology 11

GlycogenConsists of glucose monomers Is the major storage form of glucose

in animals

AP Biology

Cellulose Most abundant organic

compound on Earth herbivores have evolved a mechanism to

digest cellulose most carnivores have not

that’s why they eat meat to get their energy & nutrients

cellulose = undigestible roughage

But it tasteslike hay!

Who can liveon this stuff?!

AP Biology 13

Chitin, another important structural polysaccharide Is found in the exoskeleton of

arthropodsCan be used as surgical thread

(a) The structure of the chitin monomer.

O

CH2OH

OHHH OH

H

NH

CCH3

O

H

H

(b) Chitin forms the exoskeleton of arthropods. This cicada is molting, shedding its old exoskeleton and emergingin adult form.

(c) Chitin is used to make a strong and flexible surgical

thread that decomposes after the wound or incision heals.

OH

Figure 5.10 A–C

Structural polysaccharides

Regents Biology

Lipids Lipids are composed of C, H, O

long hydrocarbon chains (H-C) “Family groups”

fats phospholipids steroids

Do not form polymers big molecules made of smaller subunits not a continuing chain

Regents Biology

Fats Structure:

glycerol (3C alcohol) + fatty acid fatty acid =

long HC “tail” with carboxyl (COOH) group “head”

dehydration synthesis

H2O

enzyme

Regents Biology

Fats store energy Long HC chain

polar or non-polar? hydrophilic or hydrophobic?

Function: energy storage

concentrated all H-C!

2x carbohydrates cushion organs insulates body

think whale blubber!

Why do humanslike fatty foods?

Regents Biology

Saturated fats All C bonded to H No C=C double bonds

long, straight chain most animal fats solid at room temp.

contributes to cardiovascular disease (atherosclerosis) = plaque deposits

Regents Biology

Unsaturated fats C=C double bonds in

the fatty acids plant & fish fats vegetable oils liquid at room temperature

the kinks made by doublebonded C prevent the molecules from packing tightly together

mono-unsaturated?poly-unsaturated?

Regents Biology

Hydrogenation Hydrogenation adds more H and changes

double bonds to single bonds

Regents Biology

Phospholipids Structure:

glycerol + 2 fatty acids + PO4

PO4 = negatively charged

It’s just like apenguin…

A head at one end& a tail

at the other!

Regents Biology

Steroids Structure:

4 fused C rings + ?? different steroids created by attaching different

functional groups to rings different structure creates different function

examples: cholesterol, sex hormones

cholesterol

Regents Biology

Cholesterol Important cell component

animal cell membranes precursor of all other steroids

including vertebrate sex hormones high levels in blood may contribute to

cardiovascular disease

Regents Biology

From Cholesterol Sex Hormones What a big difference a few atoms can make!

Regents Biology

Proteins Most structurally & functionally diverse group Function: involved in almost everything

enzymes (pepsin, DNA polymerase) structure (keratin, collagen) carriers & transport (hemoglobin, aquaporin) cell communication

signals (insulin & other hormones) receptors

defense (antibodies) movement (actin & myosin) storage (bean seed proteins)

Regents Biology

Proteins Structure

monomer = amino acids 20 different amino acids

polymer = polypeptide protein can be one or more polypeptide

chains folded & bonded together large & complex molecules complex 3-D shape

Rubisco

hemoglobin

growthhormones

H2O

Regents Biology

Amino acids Structure

central carbon amino group carboxyl group (acid) R group (side chain)

variable group different for each amino acid confers unique chemical

properties to each amino acid like 20 different letters of an

alphabet can make many words (proteins)

—N—H

HC—OH

||O

R

|—C—

|

H

Oh, I get it!amino = NH2 acid = COOH

Regents Biology

Protein structure & function

hemoglobin

Function depends on structure 3-D structure

twisted, folded, coiled into unique shape

collagen

pepsin

Regents Biology

Building proteins Peptide bonds

covalent bond between NH2 (amine) of one amino acid & COOH (carboxyl) of another

C–N bond

peptidebond

dehydration synthesisH2O

Regents Biology

Protein structure

amino acid sequence

peptide bonds

1°

determinedby DNA R groups

H bonds

R groupshydrophobic interactions

disulfide bridges(H & ionic bonds)

3°multiple

polypeptideshydrophobic interactions

4°

2°

Regents Biology 30

Sickle-Cell Disease: A Simple Change in Primary Structure

Results from a single amino acid substitution in the protein hemoglobin

Regents Biology

Protein denaturation Unfolding a protein

conditions that disrupt H bonds, ionic bonds, disulfide bridges temperature pH salinity

alter 2° & 3° structure alter 3-D shape

destroys functionality some proteins can return to their functional shape

after denaturation, many cannot

In Biology,size doesn’t matter,

SHAPE matters!

Regents Biologyproteinsproteins

DNADNA

Nucleic Acids Function:

genetic material stores information

genesblueprint for building proteins

DNA RNA proteins

transfers informationblueprint for new cellsblueprint for next generation

Regents Biology

Nucleic Acids Examples:

RNA (ribonucleic acid) single helix

DNA (deoxyribonucleic acid) double helix

Structure: monomers = nucleotides

RNA

DNA

Regents Biology

Nucleotides 3 parts

nitrogen base (C-N ring) pentose sugar (5C)

ribose in RNA deoxyribose in DNA

phosphate (PO4) group

Are nucleic acidscharged molecules?

Nitrogen baseI’m the

A,T,C,G or Upart!

Regents Biology 35

The Structure of Nucleic Acids

Each contains a sugar, phosphate group, and nitrogenous base

The bonds are called phosphodiester bonds

3’C

5’ end

5’C

3’C

5’C

3’ endOH

Figure 5.26

O

O

O

O

Regents Biology 36

DNA Pairing Adenine pairs with Thymine (or Uracil

in RNA) Guanine pairs with Cytosine Pairing is anti-parallel Ex. If 1 side is 5’-A-T-C-G-A-A-C-C-3’

the other side is 3’-T-A-G-C-T-T-G-G-5’

Regents Biology 37

DNA The nitrogenous bases in DNA

Form hydrogen bonds in a complementary fashion

Purines ( Adenine and Guanine)

bond only with pyrimidines ( cytosine, thymine and uracil)

CHCH

Uracil (in RNA)U

Ribose (in RNA)

Nitrogenous bases Pyrimidines

CNNC

OH

NH2

CHCH O C N

HCH

HN CO

C CH3

NHN C

CH

O

O

CytosineC

Thymine (in DNA)T

NHC

N CC N

CCHN

NH2 ON

HCNHH

C C

N

NHC NH2

AdenineA

GuanineG

Purines

OHOCH2

HH H

OH

H

OHOCH2

HH H

OH

H

Pentose sugars

Deoxyribose (in DNA) Ribose (in RNA)OHOH

CHCH

Uracil (in RNA)U

4’

5”

3’OH H

2’

1’

5”

4’

3’ 2’

1’

Pyrimidines

Purines

Regents Biology 38

RNA directs protein synthesis

1

2

3

Synthesis of mRNA in the nucleus

Movement of mRNA into cytoplasm

via nuclear pore

Synthesisof protein

NUCLEUSCYTOPLASM

DNA

mRNA

Ribosome

AminoacidsPolypeptide

mRNA

Figure 5.25

Regents Biology 39

Tape Measures of Evolution Can examine familial similarities in DNA

sequences Examine molecular genealogy of DNA

to find similar species Ex. Humans and gorillas differ by only 1

amino acid

Regents Biology 40