Question

1.What is the difference between a transition and a transversion? Which type of base substitution is more common?

2.What is the difference between a missense mutation and a nonsense mutation? Between a silent mutation and a neutral mutation?

3.What is the purpose of the Ames test? How are his-bacteria used in this test?

Answer 1

Answer:

1). Substitution of one purine with another purine or one pyrimidine with another pyrimidine is called transition.

Substitution of purine with pyrimidine or pyrimidine with purine is called transversion.

Transition is more common than transversion.

2).

Missense mutation yields new amino acid but never stops the protein synthesis.

Nonsense mutation terminates protein synthesis.

Silent mutation and neutral mutation are same.

Silent mutation does not alter the amino acid of the polypeptide. Hence, silent mutations do not affect the function of the protein, it is considered as a neutral mutation.