Lecture 15

Question 1

What is mutation?

Answer 1

any alteration in DNA sequence from a single base pair substitution, deletion, insertion or several base pairs or a major alteration in the structure of a chromosome

Question 2

Types of mutation

Answer 2

Somatic (cancer)
germ line (gametes)
spontaneous
induced (nuclear)
chromosomal mutations are gross mutations (in several regions of the DNA

Question 3

Mutations at the DNA level

Answer 3

Single base substitution
Deletion of bases
Insertion of bases
Triplet repeat mutations

Question 4

Base substitution

Answer 4

silent - no change in the gene product
Missense - Amino acid substitution in the gene product (sickle cell anaemia)
Nonsense - a change in the nucleotide sequence that converts a codon for an amino acid into a termination codon

Question 5

Deletion/ insertion of bases

Answer 5

Frameshift mutations: a loss or gain of nucleotides in a DNA DNA sequence –> code is out of phase after mutation –> almost all amino acids are altered down stream - Deletion eg. Muscular Dystrophy - if multiple of three gets deleted it is a less severe form of disease

Question 6

Cystic Firbrosis

Answer 6

Autosomal recessive:
Clinical symptoms: Prenatal blockage of pancreatic ducts and reproductive ducts, postnatal accumulation of mucus in lungs, Poor digestion
- 3 base deletion, miss out on phenalalanine (in-frame deletion)

Question 7

Beta Thalassaemia

Answer 7

Autosomal recessive:

Beta globin gene - deficiency in quantity of beta globin

Question 8

Huntington disease

Answer 8

Autosomal dominant: Triplet repeat - affects neuronal development