EXAM 1

Question 1

Silent Mutation (definition and consequence)

Answer 1

D: Change in nucleotide sequence that does not change the amino acid specified by a codon

C: No change in phenotype; neutral with respect to fitness

Question 2

Missense Mutation (definition and consequence)

Answer 2

D: Change in nucleotide sequence that changes the amino acid specified by codon

C: Change in primary structure of protein; may be beneficial, neutral, or deleterious

Question 3

Nonsense Mutation (definition and consequence)

Answer 3

D: Change in nucleotide sequence that results in an early stop codon

C: Leads to mRNA breakdown or a shortened polypeptide; usually deleterious

Question 4

Frameshift Mutation (definition and consequence)

Answer 4

D: Addition or deletion of a nucleotide

C: Reading frame is shifted, altering the meaning of all subsequent codons;
almost always deleterious

Question 5

How does the structure of a protein determine its function?

Answer 5

Through shape and interactions

Question 6

REMEMBER (proteins)

Answer 6

Molecular interactions influence protein structure and function

Question 7

An enzyme…

Answer 7

decreases the activation energy of a reaction but has no effect on free energy

Question 8

What is ∆G?

Answer 8

∆G is change in Gibbs free
energy between products and reactants; any energy that is readily available to use

Question 9

Exergonic

Answer 9

releases energy, spontaneous (favors products)

Question 10

Endergonic

Answer 10

requires input of energy for the reaction to proceed, nonspontaneous (favors reactants)

Question 11

REMEMBER (spontaneous)

Answer 11

Spontaneous reactions are not necessarily fast.

Question 12

Refer to Figure 1:
- Is this reaction exergonic or endergonic?
- Will this reaction proceed spontaneously Why or why not?

Answer 12

• Since ∆G is negative, the reaction is exergonic.
• This reaction will proceed spontaneously because it is exergonic and favors the formation of products.

Question 13

Refer to Figure 2:
- What is activation energy (Ea)
- How does Ea affect the rate of a reaction?
- How does an enzyme increase the rate of a reaction?

Answer 13

• Activation energy is the kinetic energy required to reach the high-energy transition state.
• The higher the Ea, the slower the reaction.
• An enzyme brings substrates together and lowers the activation energy.

Question 14

REMEMBER (enzyme)

Answer 14

An enzyme has NO EFFECT on ∆G

Question 15

Refer to Figure 3:
- Which reactions are coupled in this figure?
- How does the coupled reaction differ from
the uncoupled reaction?

Answer 15

• A + B –> AB (uncoupled) and ATP –> ADP + Pi
• The coupled reaction is exergonic and spontaneous.

Question 16

Which of these nucleotides, AMP
or ATP, could be added to a growing RNA
chain?

Answer 16

ATP

Question 17

Initiation (concerning enzyme action)

Answer 17

Binding of substrates in a specific orientation

Question 18

Transition (concerning enzyme action)

Answer 18

Lowering of activation energy

Question 19

Termination (concerning enzyme action)

Answer 19

Release of products (which have a lower affinity for the active site)

Question 20

Competitive Inhibition

Answer 20

The regulatory molecule binds to the active site, inhibiting the substrate from doing so.

Question 21

Allosteric Regulation (activation)

Answer 21

The regulatory molecule binds to another part of the enzyme and changes its shape, making the active site available for the substrate to bind to.

Question 22

Allosteric Regulation (inhibition)

Answer 22

The regulatory molecule binds to another part of the enzyme and changes its shape, making the active site unavailable for the substrate to bind to.

Question 23

Allele

Answer 23

Different DNA sequence

Question 24

Gene

Answer 24

DNA sequences

Question 25

Environment

Answer 25

Inputs of information flow

Question 26

Phenotype

Answer 26

Output of information flow

Question 27

Fitness

Answer 27

Reproductive success

Question 28

At a molecular level, what makes an allele dominant or recessive?

Answer 28

gene products

Question 29

Why is DNA a good molecule for storing information?

Answer 29

DNA is more stable than RNA

Question 30

REMEMBER (directionality)

Answer 30

Nucleic acids have directionality (AKA polarity)

Question 31

Nonpolar covalent bond

Answer 31

Electrons are shared equally between the two atoms (placed halfway).

Question 32

Polar covalent bond

Answer 32

Electrons are not shared equally, so partial charges exist.

Question 33

REMEMBER (non-polar bond)

Answer 33

Energy input is needed to build molecules with non-polar bonds.

Question 34

NONPOLAR NOTE

Answer 34

Nonpolar bonds have higher potential energy than polar bonds.

Question 35

HYDROPHOBIC NOTE

Answer 35

Molecules or regions of a molecule that are composed primarily of nonpolar bonds are hydrophobic.

Question 36

HYDROPHILIC NOTE

Answer 36

Molecules or regions of a molecule that are composed primarily of polar bonds are hydrophilic.