EXAM 1 Flashcards
Silent Mutation (definition and consequence)
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
Missense Mutation (definition and consequence)
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
Nonsense Mutation (definition and consequence)
D: Change in nucleotide sequence that results in an early stop codon
C: Leads to mRNA breakdown or a shortened polypeptide; usually deleterious
Frameshift Mutation (definition and consequence)
D: Addition or deletion of a nucleotide
C: Reading frame is shifted, altering the meaning of all subsequent codons;
almost always deleterious
How does the structure of a protein determine its function?
Through shape and interactions
REMEMBER (proteins)
Molecular interactions influence protein structure and function
An enzyme…
decreases the activation energy of a reaction but has no effect on free energy
What is ∆G?
∆G is change in Gibbs free
energy between products and reactants; any energy that is readily available to use
Exergonic
releases energy, spontaneous (favors products)
Endergonic
requires input of energy for the reaction to proceed, nonspontaneous (favors reactants)
REMEMBER (spontaneous)
Spontaneous reactions are not necessarily fast.
Refer to Figure 1:
- Is this reaction exergonic or endergonic?
- Will this reaction proceed spontaneously Why or why not?
- Since ∆G is negative, the reaction is exergonic.
- This reaction will proceed spontaneously because it is exergonic and favors the formation of products.
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?
- 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.
REMEMBER (enzyme)
An enzyme has NO EFFECT on ∆G
Refer to Figure 3:
- Which reactions are coupled in this figure?
- How does the coupled reaction differ from
the uncoupled reaction?
- A + B –> AB (uncoupled) and ATP –> ADP + Pi
- The coupled reaction is exergonic and spontaneous.