Download Lipids, Proteins, Nucleic Acids

Chapter 6 continued
Lipids, Proteins, and
Nucleic Acids
Lipids
Lipids
• Nonpolar molecules
HH H HH HH H HH
– Long chains of –C-C-C-C-C-C-C-C-C-C H
H HH H HH HH H H
– Contain large amounts of H
– Store large amount of energy -9.0 Calories/gram
– Oils (if liquid at room temp.)
– Fats (if solid at room temp.)
– Waxes
– Steroids
To assemble a triglyceride . . .
H
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
C
HO
H
H
H
H
H
H
H
H
H
H
O
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
O
C
1
OH
C
2
OH
C
3
OH
Glycerol
C
C
HO
3 Fatty Acids
Typical Triglyceride
3 fatty acids
Glycerol
Phospholipid: variation of a triglyceride
• found in all cell membranes and membranes of organelles
Some lipids have an unusual shape
Cholesterol is in
cell membranes
Proteins
• Provide the basic building blocks for all tissues
in organisms
• Contain 4.4 Calories of energy/gram
• Basic building block is the amino acid -- 20
different kinds
?
Central
carbon
O
?
R = variable group
(20 kinds of R)
R group
examples
To join 2 amino acids . . .
H
N
H
H2O
Condensation _____?_____
A dipeptide
Basic polypeptide
Types of foldings
and spiraling to
give the final shape
to the protein
Not a protein until
polypeptide finishes
folding
Enzymes . . .
• Are made of globular proteins: have a
definite 3-D shape
• Speed up reactions so they can occur at
body temperature; enzymes are catalysts
• Can be used repeatedly to do the same
reaction
– Eventually they “wear out” and are replaced
• Have a groove or indentation in the surface
called the active site
– The molecules involved in the reaction fit into the
groove and are called the substrate molecules
How sucrase “digests” sucrose
Hydrolysis
Sucrase
What’s the difference in the active site before and after
accepting the sugar molecule?
Before
After
Induced fit: an adjustment by the enzyme to fully
fit to the substrate
• Enzymes regulate nearly all metabolic processes:
The sequence below is called a
metabolic pathway
Enzyme 1 Enzyme 2 Enzyme 3
Enzyme 4
A
B
C
D
E
Initial
Final
molecule
product
Intermediate
molecule
molecules
• Environmental conditions affect an enzyme’s shape
-denaturation happens to the enzyme outside optimum
ranges and the enzyme cannot fit to a substrate,
therefore it becomes inactive
Nucleic Acids
• DNA, 3 kinds of RNA
– monomer is called a nucleotide
Kinds of nitrogen bases
Bases linked together
to form 1/2 DNA
Complete DNA
molecule
DNA in double helix form
Dog offered for free; owner can’t
stand the way it stares.
(Internet humor)
End
It’s time for TEST Review
Easy
Questions
Question 1
The movement of particles from an area
of higher concentration to an area of
lower concentration is
A. homeostasis
B. diffusion
C. dynamic equilibrium
D. Brownian movement
Question 2
Which of the following best describes
a covalent bond?
A. Protons are gained or lost.
B. Electrons are gained or lost.
C. Electrons are shared.
D. Protons are shared.
Question 3
What causes water to creep up thin tubes?
A. Water has a high surface tension.
B. Water has a high heat of vaporization.
C. Water expands when it freezes.
D. Water has an attraction for itself and
for other molecules.
Question 4
The compound HCl gives off hydrogen
ions in water. What type of
compound is HCl?
A. an acid
B. a base
C. a buffer
D. a salt
Question 5
Which of the following is NOT
associated with lipids?
A. glycerol
B. saturated fatty acids
C. unsaturated fatty acids
D. nucleic acids
Medium Difficult
Questions
Question 1
A calcium atom has 20 electrons. When it
reacts, it loses two electrons. How does this
make calcium more stable?
A. It will then have equal numbers of
electrons and protons.
B. Its outer shelf is now empty and the next
lower level is full.
C. Losing two electrons will make calcium
neutral.
D. It becomes a different isotope.
Question
At which enzyme
concentration does
all of the available
substrate react with
the enzyme?
a.
b.
c.
d.
0.3 mg/ml
0.15 mg/ml
0.22 mg/ml
0.05 mg/ml
4
3
2
1
0
0.1 0.2 0.3 0.4 0.5
Enzyme concentration
(mg/ml)
Question 2
Which of the following occurs when a
solute reaches dynamic equilibrium in a
solvent?
A. The solute stops moving.
B. The solute disappears.
C. The solution is static.
D. The particles keep moving.
Question 3
What is the purpose of glycogen in
muscle cells?
A. Muscle cells use glycogen to make
actin and myosin proteins.
B. Muscle cells use glycogen to
stimulate contraction.
C. Muscle cells need glycogen to secrete
hormones.
D. Muscle cells break down glycogen to
provide energy for contraction.
Question
Under which conditions is enzyme A most effective?
a. 35˚C and pH 2.8
b. 40˚C and pH 3
c. 40˚F and pH 7
d. 40˚C and pH 6.8
Enzyme A
Enzyme B
Enzyme A
Question
The optimum environment for enzyme B is?
a.
b.
c.
d.
a basic medium
an acidic medium
a neutral medium
either acidic or basic
Enzyme A
Enzyme B
Enzyme A
Question 4
During the winter, ice floats on lakes. How
can a solid float on a liquid?
A. As ice forms, the molecules expand,
making the ice less dense than cold
liquid water.
B. Ice has large air pockets, so it will always
float on water.
C. All molecules that form crystalline
structures are less dense than liquids.
D. Water molecules take up less surface
area as they freeze.
Question 5
How many total atoms are involved in the following
equation?
C02 + H20 ---> H2CO3
A. 4
B. 6
C. 7
D. 12
Difficult
Questions
Question 1
Whirligig beetles are small insects that are able to
walk on the surface of water. What factor allows them to
do this?
A. Water is repelled from a whirligig beetle's
body, so the beetle does not sink.
B. Whirligig beetles have air pockets on
their feet.
C. Water attracts to itself, forming a
surface tension "film" on top of the water.
D. Whirligig beetles 'are less dense than water.
Question 2
What is the function of stored starch in potatoes?
A. It provides food for animals.
B. It stores the food for seed production.
C. It stores the energy captured during
photosynthesis.
D. It provides food for photosynthesis.
Question 3
A cellulose molecule consists of 100 monosaccharides.
How many water molecules would it take to completely
hydrolyze the cellulose into the 100 monosaccharides?
A. None, cellulose cannot be hydrolyzed.
B. 50 water molecules
C. 99 water molecules
D. 100 water molecules
Question 4
•
Temperature, ionic conditions and the pH
of surroundings all affect the rate at
which these proteins catalyze chemical
reactions.
A. Surface protiens
B. Enzymes
C. DNA
D. cyclo-pentane ring
Question
•
What are the basic building blocks of
proteins?
a.
b.
c.
d.
Nucleic acids
Peptide bonds
Amino acids
Glycerol and fatty acids
Question
•
Glucose and fructose, with the formula
C6H12O6, differ in _______.
a.
b.
c.
d.
Number of atoms
Arrangement of atoms
Kinds of atoms
Arrangement of electrons
Question
•
Which of the following would yield the
most energy per gram when oxidized?
a.
b.
c.
d.
Starch
Glycogen
Proteins
Fats
Question
•
Most _____ (i.e. polysaccharides, nucleic
acids, proteins, lipids) in cells and
organisms are synthesized from a
collection of simple precursors.
a.
b.
c.
d.
Macromolecules
Monomers
Microscopy
Mutations
That’s all . . .
Do well on your test :)