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AP Biology
Macromolecules
You are what you eat!
Chapter 5
AP Biology
Organic Compounds § Contain bonds between CARBON
glycosidic bond
AP Biology
Carbohydrates § Structure / monomer
u monosaccharide § Function
u energy u raw materials u energy storage u structural compounds
§ Examples u glucose, starch, cellulose, glycogen
glycosidic bond
AP Biology
Sugars § Most names for sugars end in -ose § Classified by number of carbons
u 6C = hexose (glucose) u 5C = pentose (ribose) u 3C = triose (glyceraldehyde)
OH
OH
H
H
HO
CH2OH
H H
H
OH
O
Glucose
H
OH
HO
O H
H HO
H
Ribose
CH2OH
Glyceraldehyde
H
H
H
H
OH
OH
O C
C
C 6 5 3
AP Biology
Numbered carbons
C
C C
C
C
C
1'
2' 3'
4'
5' 6'
O
energy stored in C-C bonds harvested in cellular respiration
AP Biology
Simple & complex sugars § Monosaccharides
u simple 1 monomer sugars u glucose
§ Disaccharides u 2 monomers u sucrose
§ Polysaccharides u large polymers u starch
OH
OH
H
H
HO
CH2OH
H H
H
OH
O
Glucose
AP Biology
Building sugars § Dehydration synthesis
| fructose
| glucose
monosaccharides
| sucrose
(table sugar)
disaccharide
H2O
AP Biology
Polysaccharides § Polymers of sugars
u costs little energy to build u easily reversible = release energy
§ Function: u energy storage
§ starch (plants) § glycogen (animals)
w in liver & muscles
u structure § cellulose (plants) § chitin (arthropods & fungi)
AP Biology
Linear vs. branched polysaccharides
starch (plant)
glycogen (animal)
energy storage
What does branching do?
Faster digestion!
slow release
fast release
AP Biology
Polysaccharide diversity § Molecular structure determines function
u isomers of glucose u structure determines function…
in starch in cellulose
AP Biology
Cellulose § Most abundant organic
compound on Earth u herbivores have evolved a mechanism to
digest cellulose u most carnivores have not:
§ that’s why they eat meat to get their energy & nutrients
§ cellulose = undigestible roughage
But it tastes like hay!
Who can live on this stuff?!
Regents Biology
Helpful bacteria § How can herbivores digest cellulose so well?
u BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals
Ruminants
Tell me about the rabbits,
again, George!
I eat WHAT!
Caprophage
Regents Biology
Proteins § Structure
u monomer = amino acids § 20 different amino acids
u polymer = polypeptide § protein can be one or more polypeptide
chains folded & bonded together § large & complex molecules § complex 3-D shape
Rubisco
hemoglobin
growth hormones
H2O
Regents Biology
Proteins § Most structurally & functionally diverse group § Function: involved in almost everything
u enzymes (pepsin, lactase, DNA polymerase) u structure (keratin, collagen) u carriers & transport (hemoglobin, aquaporin) u cell communication
§ signals (insulin & other hormones) § receptors
u defense (antibodies) u movement (actin & myosin) u storage (bean seed proteins)
Regents Biology
Amino acids § Structure
u central carbon u amino group u carboxyl group (acid) u R group (side chain)
§ variable group § different for each amino acid § confers unique chemical
properties to each amino acid w like 20 different letters of an
alphabet w can make many words (proteins)
—N— H
H
C—OH || O
R
|
—C— |
H
Oh, I get it! amino = NH2 acid = COOH
Regents Biology
Building proteins § Peptide bonds
u covalent bond between NH2 (amine) of one amino acid & COOH (carboxyl) of another
u C–N bond
peptide bond
dehydration synthesis H2O
Regents Biology
Building proteins § Polypeptide chains have direction
u N-terminus = NH2 end u C-terminus = COOH end u repeated sequence (N-C-C) is the
polypeptide backbone § can only grow in one direction
Regents Biology
Protein structure & function
hemoglobin
§ Function depends on structure u 3-D structure
§ twisted, folded, coiled into unique shape
collagen
pepsin
Regents Biology
Protein structure
amino acid sequence
peptide bonds
1°
determined by DNA R groups
H bonds
R groups hydrophobic interactions
disulfide bridges (H & ionic bonds)
3° multiple
polypeptides hydrophobic interactions
4°
2°
Regents Biology
Sulfur containing amino acids § Cysteine, Methionine § Form disulfide bridges
u covalent cross links betweens sulfhydryls u stabilizes 3-D structure
You wondered why perms smell like
rotten eggs?
H-S – S-H
Regents Biology
Protein denaturation § Unfolding a protein
u conditions that disrupt H bonds, ionic bonds, disulfide bridges… § temperature § pH § salinity
u alter 2° & 3° structure § thus, altering 3-D shape
u destroys functionality § some proteins can return to their functional shape
after denaturation, many cannot
In Biology, size doesn’t matter,
SHAPE matters!
Regents Biology proteins
DNA
Nucleic Acids § Function:
u genetic material § stores information
w genes w blueprint for building proteins
n DNA → RNA → proteins § transfers information
w blueprint for new cells w blueprint for next generation
Regents Biology
Nucleic Acids § Examples:
u RNA (ribonucleic acid) § single helix
u DNA (deoxyribonucleic acid) § double helix
§ Structure: u monomers = nucleotides
RNA DNA
Regents Biology
Nucleotides § 3 parts
u nitrogen base (C-N ring) u pentose sugar (5C)
§ ribose in RNA § deoxyribose in DNA
u phosphate (PO4) group
Are nucleic acids charged molecules?
Nitrogen base I’m the
A,T,C,G or U part!
Regents Biology
Lipids § Lipids are composed of C, H, O
u long hydrocarbon chains (H-C) § “Family groups”
u fats u phospholipids u steroids
§ Do not form polymers u big molecules made of smaller subunits u not a continuing chain
Regents Biology
Fats § Structure:
u 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 hydrocarbon chain
u polar or non-polar? u hydrophilic or hydrophobic?
§ Function: u energy storage
§ concentrated w all H-C!
§ 2x carbohydrates u cushion organs u insulates body
§ think whale blubber!
Why do humans like fatty foods?
Regents Biology
Saturated fats § All C bonded to H § No C=C double bonds
u long, straight chain u most animal fats u solid at room temp.
§ contributes to cardiovascular disease (atherosclerosis) = plaque deposits
Regents Biology
Unsaturated fats § C=C double bonds in
the fatty acids u plant & fish fats u vegetable oils u liquid at room temperature
§ the kinks made by double bonded C prevent the molecules from packing tightly together
mono-unsaturated? poly-unsaturated?
Regents Biology
Phospholipids § Structure:
u glycerol + 2 fatty acids + PO4
§ PO4 = negatively charged (which means the head molecule is…)
It’s just like a penguin…
A head at one end & a tail
at the other!
Regents Biology
Phospholipids in water § Hydrophilic heads “attracted” to H2O § Hydrophobic tails “hide” from H2O
u can self-assemble into “bubbles” § bubble = “micelle” § can also form a phospholipid bilayer § early evolutionary stage of cell?
bilayer
water
water
Regents Biology
Steroids § Structure:
u 4 fused C rings + ?? § different steroids created by attaching different
functional groups to rings § different structure creates different function
u examples: cholesterol, sex hormones
cholesterol
Regents Biology
Cholesterol § Important cell component
u animal cell membranes u precursor of all other steroids
§ including vertebrate sex hormones u high levels in blood may contribute to
cardiovascular disease
Regents Biology
From Cholesterol → Sex Hormones § What a big difference a few atoms can make!