WEEK 13 (Spontaneous and induced mutations)

Question 1

Define Spontaneous mutations

Answer 1

Changes in the nucleotide sequence of genes that appear to occur naturally. No specific agents are associated with their occurrence.

Question 2

Define Induced mutations

Answer 2

Mutations that result from the influence of exogenous factors. Induced mutations may be the result of either natural or artificial agents.

Question 3

Define Mutation rate

Answer 3

The likelihood that a gene will undergo a mutation in a single generation or in forming a single gamete

Question 4

What are mutation hot spots?

Answer 4

DNA sequences that appear to be highly susceptible to mutation

Question 5

Describe B-thalassemia

Answer 5

B-thalassemia is an inherited autosomal recessive blood disorder resulting from a reduction or absence of haemoglobin.

Mutations in the B global gene (HBB gene) cause B-thalassemia. The HBB gene encodes the 146-amino-acid B global polypeptide. Two B-globin polypeptides associate with two B-globin polypeptides to form the adult haemoglobin tetramer.

Most mutations change a single nucleotide within or surrounding the HBB gene or create small insertions or deletions.

Question 6

Describe the HBB gene

Answer 6

The HBB gene spans 1.6 kilo bases of DNA on the short arm of chromosome 11 and is made up of three exons and two introns.

Question 7

Describe the mutations throughout and surrounding the HBB gene

Answer 7

Short insertions, deletions and duplications that alter coding sequences, create frameshift stop codons and alter mRNA splicing