Exam 1: Topic 4, 5, and 6

Question 1

Explain the mechanism of action for how acids, bases and heat cause denaturation of proteins.

Answer 1

○ Heat: denaturation of proteins with molecular vibration, breaking hydrogen bonds.
○ How does a strong acid denature a protein?
§ H+ ions are attracted to the carboxylic acid of an amino acid residue and the charge between the positive and negative residues is neutralized.
○ How does a strong base denature a protein?
OH- ions are attracted to the amine group of an amino acid residue and the charge between the positive and negative residues is neutralized, by removing a hydrogen atom from the amine creating H2O (dehydration reaction).

Question 2

What is the consequence to bacteria if their proteins are denatured?

Answer 2

○ The bacteria will most likely lose its ability to function properly and potentially die.
○ Denaturation disrupts the proteins 3D structure, preventing them from carrying out their vital biological roles like metabolism, replication, and cell division.

Question 3

Describe types of point mutations:

Answer 3

*DNA base is swapped for another.
1. Silent: no amino acid change
2. Missense: one amino acid is swapped for another (depends which one)
3. Nonsense: premature stop codon.

Question 4

Describe frame shift mutation:

Answer 4

1. Insertions and deletions of DNA base.

Question 5

Spontaneous mutation:

Answer 5

a genetic change that occurs without any known cause, such as during DNA replication (can be passed down to offspring).

Question 6

Induced mutation:

Answer 6

§ a genetic change that occurs without any known cause, such as during DNA replication (can be passed down to offspring).

Question 7

Compare the following chemical mutagens as discussed in
class: base analogs (also known as nucleoside analogs), deaminating agents and
acridine dyes (benzopyrene is an example). Explain the mechanism of action for
each chemical mutagen (i.e. HOW do the mutagens change, or mutate the DNA)
and whether the mutagen induces frameshift or point mutations.

Answer 7

Base analog: molecules that can replace normal bases in nucleic acids.
Incorporate in the wrong place, Mispair with the wrong base

Deaminating Agent: chemicals that remove amino groups from DNA’s nucleotide bases

Acridine dye: Acridines are hydrophobic and can intercalate within DNA and RNA by forming hydrogen bonds and stacking between base pairs. This can lead to DNA crosslinks and strand breaks.