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Carbohydrates
sugar sugar sugar sugar sugar sugar
Carbohydrates
 Carbohydrates are composed of C, H, O
 Function:
carbo - hydr - ate
CH2O
energy storage
u structural materials
u
 Monomer: monosaccharide
 ex: sugars, starches, cellulose
Simple & complex sugars
 Monosaccharides
simple 1 monomer sugars
u Glucose, fructose, galactose
CH2OH
H
O
H
OH
H
H
OH
HO
u
 Disaccharides
2 monomers
u Sucrose, Lactose, Maltose
u
 Polysaccharides
large polymers
u Starch, Cellulose,
Glycogen, Chitin
u
Glucose
H
OH
Building sugars
 Dehydration synthesis
monosaccharides
|
glucose
H2O
|
fructose
disaccharide
|
sucrose
(table sugar)
Polysaccharides
 Polymers of monosaccharides
costs little energy to build
u easily reversible = release energy
u
 Function:
u
energy storage
 starch (plants)
 glycogen (animals)
 in liver & muscles
u
structure
 cellulose (plants)
 chitin (arthropods & fungi)
Digesting starch vs. cellulose
starch
easy to
digest
enzyme
cellulose
hard to
digest
enzyme
Cellulose
 Most abundant organic
compound on Earth
herbivores have evolved a mechanism to
digest cellulose
u most carnivores have not
u
 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?!
Cow
can digest cellulose well;
no need to eat other sugars
Gorilla
can’t digest cellulose well;
must add another sugar
source, like fruit to diet
Helpful bacteria
 How can herbivores digest cellulose so well?
u
u
BACTERIA live in their digestive systems & help digest
cellulose-rich (grass) meals
This is called SYMBIOSIS
Caprophage
Ruminants
Lipids
Lipids
 Lipids are composed of C, H, O
u
long hydrocarbon chains (H-C)
 “Family groups”
fats
u phospholipids
u steroids
u
 Do not form polymers
big molecules made of smaller subunits
u not a continuing chain
u
FATS
long term energy storage
concentrated energy
Building Fats
 Triglycerol (fancy name for FAT)
u
Glycerol linked to 3 fatty acids
Fats store energy
 Long HC chain
u
hydrophilic or hydrophobic?
 Function:
u
Why do humans
like fatty foods?
energy storage
 concentrated
 all H-C!
 2x carbohydrates
cushion organs
u insulates body
u
 think whale blubber!
Saturated fats
 All C bonded to H
 No C=C double bonds
long, straight chain
u most animal fats
u solid at room temp.
u
 contributes to
cardiovascular disease
(atherosclerosis)
= plaque deposits
Unsaturated fats
 C=C double bonds in
the fatty acids
plant & fish fats
u vegetable oils
u liquid at room temperature
u
 the kinks made by double
bonded C prevent the
molecules from packing
tightly together
mono-unsaturated?
poly-unsaturated?
Saturated vs. unsaturated
saturated
unsaturated
Phospholipids
 Hydrophilic heads “attracted” to H2O
 Hydrophobic tails “hide” from H2O
Why is this important?
 Phospholipids create a barrier in water
define outside vs. inside
u they make cell membranes!
u
Steroids
 Structure:
u
4 fused rings
 different steroids created by attaching different
molecules to rings
 different structure creates different function
u
examples: cholesterol, sex hormones
cholesterol
Cholesterol
 Important cell component
helps keep
cell membranes
fluid & flexible
animal cell membranes
u high levels in blood may contribute to
cardiovascular disease
u
Proteins
Proteins
Multipurpose
molecules
Proteins
 Most structurally & functionally diverse group
 Function: involved in almost everything in
living things
u
u
u
u
u
u
u
enzymes (pectinase, amylase)
structure (skin, hair, nails)
carriers & transport (hemoglobin)
cell communication (insulin & other hormones)
defense (antibodies)
movement (muscle)
storage (nuts/seeds)
Proteins
 Structure
u
monomer = amino acids
 20 different amino acids
u
polymer = polypeptide
 large & complex molecules
 complex 3-D shape
hemoglobin
Rubisco
growth
hormones
Monomer: Amino acid
 Structure
H
central carbon
u amino group
u carboxyl group (acid)
u R group (side chain)
u
H O
| ||
—C— C—OH
—N—
|
H
R
 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)
Oh, I get it!
amino = NH2
acid = COOH
Protein structure & function
 Function depends on structure
u
3-D structure
 twisted, folded, coiled into unique shape
pepsin
hemoglobin
collagen
Sickle cell anemia
I’m
hydrophilic!
Just 1
out of 146
amino acids!
But I’m
hydrophobic!
Protein denaturation
 Unfolding a protein
u
In Biology,
size doesn’t matter,
SHAPE matters!
conditions that disrupt bonds
 temperature
 pH
 salinity
u
alter structure
 alter 3-D shape
u
destroys function
 some proteins can return to their functional shape
after denaturation, many cannot