Mini Lesson 4: Genetic Mutations Self-Check

Which of the following mutations is most likely to be disruptive to protein synthesis or function?

UAU to UAC
Incorrect. UAU to UAC results in tyrosine being coded in each case. There is no disruption to protein synthesis or function.
UAU to UUU
Incorrect. UAU to UUU results in a change from tyrosine to phenylalanine. This is a similar amino acid to tyrosine and so the chances of disruption are slight unless tyrosine is particularly important to function.
UAU to UAA
Correct! UAU to UAA results in a stop code which prevents further synthesis of the protein. This will be the most drastic effect and will lead to a non-functioning protein. (This is a nonsense mutation.)
UAU to CAU
Incorrect. UAU to CAU results in a change from tyrosine to histidine. Only one amino acid is altered and the protein may still be functional if the tyrosine is not crucial to activity.

Which DNA segment deletion would cause a frameshift mutation?

TAT
Incorrect
GAGTC
Correct! It has 5 bases and is not divisible by 3, thereby causing a frameshift.
TACTAC
Incorrect
GCATGACCC
Incorrect

A germline mutation passes from generation to generation because it occurs during the DNA replication before

Mitosis
Incorrect
Meiosis
Correct! Mutations that form during meiosis result in ova/sperm that pass the mutation to future offspring.
Fertilization
Incorrect
RNA replication
Incorrect

A man and woman of normal height have a son with achondroplasia. They want to have another child and wonder what the risk is that he or she will have this form of dwarfism. The risk is:

Zero
Incorrect
The same as for any other child in the population
Correct! This situation most likely represents a de novo mutation or a mutation that originated in a new mutation in one of his parent’s gamete- and future siblings have no higher risk of inheriting it than does anyone else in the general popultion.
25%
Incorrect
50%
Incorrect