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Chapter 5.
Macromolecules
AP Biology
2005-2006
Macromolecules
 Smaller organic molecules join together
to form larger molecules

macromolecules
 4 major classes of macromolecules:
carbohydrates
 lipids
 proteins
 nucleic acids

AP Biology
2005-2006
Polymers
 Long molecules built by linking chain
of repeating smaller units
polymers
 monomers = repeated small units
 covalent bonds

AP Biology
2005-2006
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

AP Biology
requires energy
& enzymes
2005-2006
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

AP Biology
ex: digestion is
hydrolysis
2005-2006
Carbohydrates
AP Biology
2005-2006
Carbohydrates
 Carbohydrates are composed of C, H, O
carbo - hydr - ate
CH2O
(CH2O)x
C6H12O6
 Function:
energy
 raw materials
materials

energy storage
 structural

 Monomer: sugars

ex: sugars & starches
AP Biology
2005-2006
Sugars
 Most names for sugars end in -ose
 Classified by number of carbons
6C = hexose (glucose)
 5C = pentose (fructose, ribose)
 3C = triose (glyceraldehyde)

AP Biology
2005-2006
Simple & complex sugars
 Monosaccharides
simple 1 monomer sugars
 glucose

 Disaccharides
2 monomers
 sucrose

 Polysaccharides
large polymers
 starch

AP Biology
2005-2006
Building sugars
 Dehydration synthesis
monosaccharides
|
glucose
|
glucose
disaccharide
|
maltose
glycosidic linkage
AP Biology
2005-2006
Polysaccharides
 Polymers of sugars
costs little energy to build
 easily reversible = release energy

 Function:

energy storage
 starch (plants)
 glycogen (animals)

building materials = structure
 cellulose (plants)
 chitin (arthropods & fungi)
AP Biology
2005-2006
Polysaccharide diversity
 Molecular structure determines function
isomers of glucose
 How does structure influence function…

AP Biology
2005-2006
Digesting starch vs. cellulose
AP Biology
2005-2006
Cow
can digest cellulose well; no
need to eat supplemental
sugars
Gorilla
can’t digest cellulose well;
must supplement with sugar
source, like fruit
AP Biology
2005-2006
Glycemic index
 Which food will get into your
blood more quickly?





AP Biology
apple
rice cakes
corn flakes
bagel
peanut M&M
2005-2006
Glycemic index
 Which food will get into your
blood more quickly?





AP Biology
apple
rice cakes
corn flakes
bagel
peanut M&M
36
82
84
72
33
2005-2006
Lipids
AP Biology
2005-2006
Lipids
 Lipids are composed of C, H, O

long hydrocarbon chain
 Diverse group
fats
 phospholipids
 steroids

 Do not form polymers
big molecules made of
subunit smaller molecules
 not a continuing chain

AP Biology
2005-2006
Fats
 Structure:

glycerol (3C alcohol) + fatty acid
 fatty acid = long HC “tail” with COOH group
at “head”
dehydration synthesis
AP Biology
2005-2006
Fat
 Triacylglycerol
3 fatty acids linked to glycerol
 ester linkage = between OH & COOH

AP Biology
2005-2006
Dehydration synthesis
AP Biology
2005-2006
Fats
 Long HC chain


polar or non-polar?
hydrophilic or hydrophobic?
 Function:

energy storage
 very rich
 2x carbohydrates


cushion organs
insulates body
 think whale blubber!
“Let’s
go to the video tape!”
AP Biology
(play movie here)
2005-2006
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
AP Biology
2005-2006
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
AP Biology
2005-2006
Cholesterol
 Important cell component
animal cell membranes
 precursor of all other steroids

 including vertebrate sex hormones

AP Biology
high levels in blood may contribute to
cardiovascular disease
2005-2006
Proteins
AP Biology
2005-2006
Proteins
 Most structurally & functionally diverse

group of biomolecules
Function:

involved in almost everything







AP Biology
enzymes
structure (keratin, collagen)
carriers & transport (membrane channels)
receptors & binding (defense)
contraction (actin & myosin)
signaling (hormones)
storage (bean seed proteins)
2005-2006
Proteins
 Structure:

monomer = amino acids
 20 different amino acids

polymer = polypeptide
 protein can be 1 or more polypeptide chains
folded & bonded together
 large & complex molecules
 complex 3-D shape
AP Biology
2005-2006
Amino acids
 Structure:
central carbon
 amino group
 carboxyl group (acid)
 R group (side chain)

 variable group
 confers unique
chemical properties
of the amino acid
AP Biology
H O
H
| ||
—N—
—C— C—OH
|
H
R
2005-2006
Nonpolar amino acids
 nonpolar & hydrophobic
Why are these nonpolar & hydrophobic?
AP Biology
2005-2006
Polar amino acids
 polar or charged & hydrophilic
AP Biology
Why are these polar & hydrophillic?
2005-2006
Building proteins
 Peptide bonds: dehydration synthesis
linking NH2 of 1 amino acid to
COOH of another
 C–N bond

AP Biology
peptide
bond
2005-2006
Building proteins
 Polypeptide chains
N-terminal = NH2 end
 C-terminal = COOH end
 repeated sequence (N-C-C) is the
polypeptide backbone

 grow in one direction
AP Biology
2005-2006
Protein structure & function
 function depends on structure

3-D structure
 twisted, folded, coiled into unique shape
pepsin
hemoglobin
AP Biology
2005-2006
collagen
Protein structure & function
 function depends on structure

all starts with the
order of amino acids
 what determines that order of
amino acids?
lysozyme: enzyme in tears & mucus that kills bacteria
“Let’s
go to the video tape!”
AP Biology
(play movie here)
the 10 glycolytic enzymes
used to breakdown glucose
2005-2006
to make
ATP
Primary (1°) structure
 Order of amino acids in chain
amino acid sequence
determined by DNA
 slight change in amino acid
sequence can affect protein’s
structure & it’s function

 even just one amino acid change
can make all the difference!
AP Biology
2005-2006
Sickle cell anemia
“Let’s
go to the video tape!”
AP Biology
(play movie here)
2005-2006
Denature a protein
 Disrupt 3° structure
 pH

salt
 temperature

unravel or denature protein

disrupts H bonds, ionic bonds &
disulfide bridges
 Some proteins can
return to their
functional shape
after denaturation,
many cannot
AP Biology
2005-2006
Any Questions??
AP Biology
2005-2006