AP Biology
John D. O’Bryant School of
Mathematics and Science
September 12, 2012
AP Biology
Agenda
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Do Now (Quiz)
Macromolecules (review)
The Occurrence of Water in Living Things
Qualitative Tests of Biological Macromolecules
AP Biology
Do Now (Quiz)
 1. Used to carry the genetic code
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(A)Proteins
(B) Carbohydrates
(C) Nucleic acids
(D)Lipids
(E) Steroids
AP Biology
Do Now (Quiz)
 2. Synthesized at the ribosome
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(A)Proteins
(B) Carbohydrates
(C) Nucleic acids
(D)Lipids
(E) Steroids
AP Biology
Do Now (Quiz)
 3. Includes glycogen, chitin, cellulose, and
glucose
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(A)Proteins
(B) Carbohydrates
(C) Nucleic acids
(D)Lipids
(E) Steroids
AP Biology
Do Now (Quiz)
 4. Used for insulation and buoyancy in
marine Arctic animals
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

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(A)Proteins
(B) Carbohydrates
(C) Nucleic acids
(D)Lipids
(E) Steroids
AP Biology
The Occurrence of Water in Living Things
 1. All living organisms consist mostly of water.
 2. The adult human body is about 60% water, by weight, and 75% by volume.
 3. As much as 95% of the weight of some plants is due to the water they contain.
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Experimental Question: ________________________________________
Hypothesis: ___________________________________________________________
Materials Available:
Triple beam balance
Incubator
Grass
Assorted vegetables
Procedure:
____________________________________________________________________
AP Biology
Classwork
1.
a.
1.
2.
3.
4.
5.
6.
7.
AP Biology
Draw the electron-shell diagrams of the following:
water b. carbon dioxide c. methane d. hydrogen
sulfide
Illustrate electron transfer and ionic bonding in sodium
chloride.
Compare and contrast atomic number and atomic mass.
Oxygen has 6 electrons in its outermost shell. How many
covalent bonds can an atom of oxygen form?
Explain why the noble gases are unreactive.
What is a buffer? What makes them important?
Illustrate a dehydration reaction between two amino
acids.
Illustrate a hydrolytic reaction in a disaccharide.
Polysaccharide diversity
 Molecular structure determines function
in starch
in cellulose
isomers of glucose
 structure determines function…

AP Biology
Digesting starch vs. cellulose
starch
easy to
digest
enzyme
cellulose
hard to
digest
enzyme
AP Biology
only bacteria can digest
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
AP Biology
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
AP Biology
Helpful bacteria
 How can herbivores digest cellulose so well?

BACTERIA live in their digestive systems & help digest
cellulose-rich (grass) meals
Caprophage
Ruminants
AP Biology
Tell Ime
about
eat
the rabbits,
WHAT!
again,
George!
EAT
Let’s build
X some
Carbohydrates!
AP Biology
2010-
Lipids: Fats & Oils
AP Biology
Lipids
long term energy storage
concentrated energy
AP Biology
2006-
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

AP Biology
Fats
 Structure:

glycerol (3C alcohol) + fatty acid
 fatty acid =
long HC “tail” with carboxyl (COOH) group “head”
enzyme
H2O
dehydration synthesis
AP Biology
Building Fats
 Triacylglycerol
3 fatty acids linked to glycerol
 ester linkage = between OH & COOH

hydroxyl
AP Biology
carboxyl
Dehydration synthesis
H2O
dehydration synthesis
enzyme
H2O
enzyme
H2O
AP Biology
enzyme
HO
Fats store energy
 Long HC chain
Why do humans
like fatty foods?
polar or non-polar?
 hydrophilic or hydrophobic?

 Function:

energy storage
 concentrated
 all H-C!
 2x carbohydrates
cushion organs
 insulates body

AP Biology
 think whale blubber!
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
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?
AP Biology
Saturated vs. unsaturated
saturated
unsaturated
AP Biology
Phospholipids
 Structure:

glycerol + 2 fatty acids + PO4
 PO4 = negatively charged
It’s just like a
penguin…
A head at one end
& a tail
at the other!
AP Biology
Phospholipids
 Hydrophobic or hydrophilic?
fatty acid tails = hydrophobic
 PO4 head = hydrophillic
“attracted to water”
 split “personality”

Come here,
No, go away!
Come here,
No, go away!
interaction with H2O
is complex & very
important!
AP Biology
“repelled by water”
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?
water
bilayer
AP Biology
water
Why is this important?
 Phospholipids create a barrier in water
define outside vs. inside
 they make cell membranes!

Tell them
about soap!
AP 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
AP Biology
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
Cholesterol
Important component of cell membrane
AP Biology
helps keep
cell membranes
fluid & flexible
From Cholesterol  Sex Hormones
 What a big difference a few atoms can make!
AP Biology
Let’s build some
Lipids!
AP Biology
2006-
Ghosts of Lectures Past
(storage)
AP Biology
2007-
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 them
about soap!
AP Biology