AP Biology

Chapter 5.

Macromolecules

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Macromolecules

Smaller organic molecules join together

to form larger molecules

macromolecules

4 major classes of macromolecules:

carbohydrates

lipids

proteins

nucleic acids

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Polymers

Long molecules built by linking chain

of repeating smaller units

polymers

monomers = repeated small units

covalent bonds

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How to build a polymer

Condensation reaction

dehydration synthesis

joins monomers by “taking” H2O out

1 monomer provides OH

the other monomer provides H

together these

form H2O

requires energy

& enzymes

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How to break down a polymer

Hydrolysis

use H2O to break apart monomers

reverse of condensation reaction

H2O is split into H and OH

H & OH group attach where the covalent

bond used to be

ex: digestion is

hydrolysis

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Carbohydrates

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Carbohydrates

Carbohydrates are composed of C, H, O

carbo - hydr - ate

CH2O

(CH2O)x C6H12O6

Function:

1. energy 2. energy storage

3. raw materials 3. structural materials

Monomer: monosaccharides (sugars)

Polymer: polysaccharide

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Carbohydrates include Sugars

Most names for sugars end in -ose

Classified by number of carbons

6C = hexose (glucose)

5C = pentose (fructose, ribose)

3C = triose (glyceraldehyde)

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What functional groups?

carbonyl

ketone

aldehyde

hydroxyl

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Sugar structure

5C & 6C sugars form rings in aqueous solutions

in cells!

Carbons are numbered

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Numbered carbons

C

CC

C

C

C

1'

2'3'

4'

5'

6'

O

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Simple & complex sugars

Monosaccharides (simple)

simple 1 monomer sugars

glucose

Disaccharides (simple)

2 monomers

sucrose

Polysaccharides (complex)

large polymers

starch

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Building sugars

Dehydration synthesis

|

glucose

|

glucose

glycosidic linkage

monosaccharides disaccharide

|

maltose

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Other examples:

• Sucrose = glucose + fructose

• Maltose = glucose + glucose

• Lactose = glucose + galactose

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Polysaccharides

Polymers of sugars

costs little energy to build

easily reversible = release energy

Function:

1. energy storage starch (plants)

glycogen (animals)

2. building materials = structure cellulose (plants)

chitin (arthropods & fungi)

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POLYSACCHARIDES~ “many sugars”

Ex: STARCH • polymer of αlpha glucose • linked by α 1-4 glycosidic linkages

Function: Energy storage in PLANTSMost animals have the enzymes to hydrolyze

starch, toohttp://www.langara.bc.ca/biology/mario/Assets/Amylopectin.jpg

http://www.district87.org/biology87/apbio/biochem/Activity6_notes.pdf

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POLYSACCHARIDES~ “many sugars”

TWO KINDS OF STARCH:amylose = unbranched starch

amylopectin = branched starch

http://www.langara.bc.ca/biology/mario/Assets/Amylopectin.jpg

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POLYSACCHARIDES~ “many sugars”

EX: GLYCOGENalpha 1-4 glycosidic bonds like starchMore branched than amylopectin

FUNCTION:Energy storage in ANIMALS

Stored in liver and muscle tissue

http://www.abcbodybuilding.com/magazine04/scientific.htm

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POLYSACCHARIDES~ “many sugars”

Example: CELLULOSE (PLANTS ) FUNCTION: Structural

Major component in cell wallsMost abundant organic compound on Earthbeta (ß) 1-4 glycosidic linkages

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• Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta 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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POLYSACCHARIDES

EX: CHITIN

FUNCTION: StructuralStructural polysaccharide made from ß glucose with a NITROGEN containing group attached

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Major component of:Exoskeletons in Arthropods

Cell walls in Fungi Dissolvable surgical thread

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Lipids: Fats & Oils

AP Biology 2006-2007

Lipidslong term energy storage

concentrated energy

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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

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Fats

Structure:

glycerol (3C alcohol) + fatty acid

fatty acid =

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

dehydration synthesis

H2O

enzyme

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Building Fats

Triacylglycerol (trigyceride)

3 fatty acids linked to glycerol

ester linkage = between OH & COOH hydroxyl carboxyl

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Dehydration synthesis

dehydration synthesis

H2O

H2O

H2O

H2O

enzyme

enzyme

enzyme

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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?

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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

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Unsaturated fats

C=C double bonds in

the fatty acids

plant & fish fats

vegetable oils

liquid at room temperature

the kinks made by double

bonded C prevent the

molecules from packing

tightly together

mono-unsaturated?poly-unsaturated?

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Saturated vs. unsaturated

saturated unsaturated

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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!

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Phospholipids

Hydrophobic or hydrophilic?

fatty acid tails =

PO4 head =

split “personality”

interaction with H2O

is complex & very

important!“repelled by water”

“attracted to water”

Come here,No, go away!Come here,No, go away!

hydrophobic

hydrophillic

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Phospholipids in water

Hydrophilic heads “attracted” to H2O

Hydrophobic tails “hide” from H2O

can self-assemble into “bubbles”

bubble = “micelle”

can also form a phospholipid bilayer

early evolutionary stage of cell?

bilayer

water

water

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Why is this important?

Phospholipids create a barrier in water

define outside vs. inside

they make cell membranes!

Tell themabout soap!

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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

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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

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Cholesterol

helps keep

cell membranes

fluid & flexible

Important component of cell membrane

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

AP Biology 2006-2007

Let’s build some

Lipids!

AP Biology 2007-2008

Ghosts of Lectures Past

(storage)

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Phospholipids & cells

Phospholipids of cell membrane double layer = bilayer

hydrophilic heads on outside in contact with aqueous solution outside of

cell and inside of cell

hydrophobic tails on inside form core

forms barrier between cell & external environment

Tell themabout soap!