Proteins, Enzymes, and Metabolism
Review Package
Biol 12:
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A. Proteins:
1.
Enzymes
are proteins that control chemical reactions.
2. Amino acids are the monomers for a
protein
consists of three groups; an amino group, an
. An amino acid
carboxyl
group and
the R group, because it is the Remainder of the molecule. Amino acids differ from one
another by their
R
group.
3. A bond that joins two amino acids is called a
A
polypeptide
4. The
primary
by peptide bonds. The
peptide
bond .
is a single chain of amino acids.
structure is the linear sequence of the amino acids joined
secondary
structure of a protein comes about
when the polypeptide takes on a particular orientation in space. The
tertiary
structure of a polypeptide is its final three-dimensional shape. Separate polypeptides are
arranged to give some proteins a fourth level of structure, termed the
quaternary
structure, such as hemoglobin.
5. When proteins are exposed to extremes in heat and pH, they undergo an irreversible
change in shape called
denaturation
.
6. The peptide bond is a type of reaction called
synthesis
dehydration
where a water molecule is removed
when 2 monomers (in this case, they are
amino
are “spliced” together. The reverse reaction is called
reaction, a water molecule is
monomers.
added
acids
hydrolysis
)
. In this
to break the bond between two
Proteins, Enzymes, and Metabolism
Review Package
Biol 12:
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7. Utilize the following terms to label the diagram below: condensation, H2O,
disaccharide, and monosaccharide.
a. condensation (dehydration synthesis)
b. (I forgot to add this word)
hydrolysis
c. monosaccharide c. monosaccharide
d. disaccharide
e. water
8. Match the following answers for proteins to one of the statements below.
a. enzymes
b. R Group
c. polypeptide
d. amino acids
e. secondary structure
f. tertiary structure
f.
protein’s final three-dimensional shape
b.
accounts for differences in amino acids
c.
a single chain of amino acids
e.
alpha helix of a polypeptide strand
d.
monomer subunits of a protein
a.
proteins that speed up chemical reactions
B. Energy and Enzymes:
1. Entropy is a measure of
form of energy has
less
of energy such as heat has
eventually result in
universe is always
2.
Coupling
randomness
or disorder. An organized, usable
entropy, whereas an unorganized, non-usable form
greater
entropy. Energy conversions
loss of heat
, and therefore the entropy of the
increasing
.
occurs when the energy released by an exergonic
reactions is used to drive an endergonic reaction. What molecule is often coupled to
cellular reactions that require an input of energy?
ATP
Proteins, Enzymes, and Metabolism
Review Package
Biol 12:
3. A metabolic
pathway
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begins with a particular reactant, terminates
with an end product, and has many minute steps in between. A
is a substance that participates in a reaction. A
reactant
product
is a
substance that is formed by the reaction. The reactants in an enzymatic reaction are
called the
substrate
4. An
enzyme
for that enzyme.
is a protein molecule that functions as an organic catalyst
to speed up a chemical reaction.
5. The energy that must be added to cause molecules to react with on another is called
the
activation
energy
. Enzymes
decrease
the amount of energy for activation to occur.
6. When an enzyme forms a complex with its substrate, the small part of the enzyme
that complexes with the substrate is called the
In the
active
lock-and-key
site
model, the active site
undergoes a slight change in shape in order to accommodated the substrate. Only a
small amount of enzyme is actually needed in a cell because enzymes are not
used up
.
7. Enzymes are very
specific
their
.
substrates
in their action and are named for
8. As the temperature rises, why in there an increase in enzyme activity? Molecules
move faster, and therefore they will bump into each other faster, and the reaction will
proceed faster.
9. When an enzyme’s shape changes due to high temperature or extreme pH, the
enzyme is said to be
10. In
feed-back
denatured
.
inhibition, a product produced in high
amounts by an enzymatic reaction can inhibit the enzyme’s activity. The end product of
Proteins, Enzymes, and Metabolism
Review Package
Biol 12:
an enzymatic pathway binds at an allosteric site on the
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initial
enzyme of the pathway.
11. In
competitive
inhibition, another molecule is so close in
shape to the enzyme'’ substrate that it can compete with the true substrate for the
enzyme’s active site. In
allosteric
inhibition, a molecule binds to an
enzyme, but not at the active site. This other site is called the
site is called the
OOPS!
regulator
site and causes a shift in the three-
dimensional structure.
12.
Coenzymes
and serve as
are organic molecules that bind to enzymes
carriers
Vitamins
for chemical groups or electrons.
are small organic molecules that are required in
trace amounts in our diet for the synthesis of coenzymes.
13. Consider the following reactions and answer the question below.
a. A + B  C + D + Energy
b. Energy + C + D  A + B
c. A + B  C + D
Reaction
b is considered endergonic, whereas reaction a
exergonic. In reaction (a) above, the products C and D have
is considered
less
(more/less)
energy than the reactants A and B. In reaction (b) above, the products A and B have
(more/less) energy than the reactants C and D. Reaction c
is at equilibrium. In
order to make reaction c go to the right, one of the products could be used as a
reactant
in another reaction.
14. Use the following terms to label this diagram: substrate, enzyme, active site,
enzyme-substrate complex, product.
c. active site
a. substrates
b. enzyme
d. E-S complex
e. product
f. enzyme
Proteins, Enzymes, and Metabolism
Review Package
Biol 12:
15. Consider this metabolic pathway:
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A-E1 B-E2 C-E3 D
If E1 - E3 represents different enzymes, letters A,B,C are considered
reactants
or substrates in the reactions, whereas letters B, C, and D would be considered
products
called a
. As a result of the action of E2,, B is now
substrate
for E2, and C is the product.
16. When the substrate binds to the enzyme, the enzyme undergoes a slight alteration in
shape to achieve optimum fit. This concept is termed the
induced-fit
model.
17. For each of the following characteristics of enzymes, put T for true or F for false.
t
Each reaction in a cell uses a specific enzyme
t
(a better word would be REGULATES)
t
Named for their substrates
f
Enzymes and products form a complex
t
Substrate binds to enzyme at active site
f
Increase in temperature causes decreased activity (unless well beyond optimal)
t
Each enzyme has an optimal temperature
f
All enzymes have the same optimal pH
Slows down chemical reactions
18. The thyroid gland releases a hormone called
thryroxin
acts on cells, causing them to
their
increase
which
metabolism
If iodine is lacking in the diet, the thyroid gland enlarges, producing a
goiter
As a result, when there are low levels of thyroxin in the blood, called
Hypothroidism no negative feedback occurs, and the anteriaor pituitary continues
to produce
thyroid-stimulating hormone (TSH ), which stimulates the
thyroid to hypertrophy.
Biol 12:
Proteins, Enzymes, and Metabolism
Review Package
19. Thyroxin increases the
metabolic
rate in which glucose is
broken down.
20. Describe the process that controls the release of thyroxin from the thyroid gland.
(including the hypothalmus) ?What is this process called? Negative feed-back inhibition
1.hypothalamus - receives nervous message - needs to increase metabolism
2. pituitary gland receives chemical message from hypo. (Releasing hormones)
3. Pituitary releases TSH
4. Thyroid receives TSH (chemical message)
5. Thyroid released Thyroxin
6. Thyroxin concentrations build up in blood
7. High [thyroxin] is detected - nervous message is sent to hypothalamus
8. Hypothalamus receives message, and stops sending Releasing Hormones to
pituitary.
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