Prevalence of Inherited Disorders

Question 1

Each autosomal gene pair comprises of?

Answer 1

1 maternal allele

1 paternal allele

Question 2

What is a genetic polymorphism?

Answer 2

Two or more variants of an allele

Question 3

Give 3 examples of allele groups which have genetic polymorphisms

Answer 3

ABO blood group
Rhesus blood group
HLA cell surface markers

Question 4

Define exon and intron

Answer 4

Exon = coding region
Intron = non coding

Question 5

Describe what a single nucleotide polymorphism is

Answer 5

A point mutation on a gene

Question 6

Describe what a Restriction Fragment Length polymorphism is

Answer 6

Usually, a restriction enzyme would cleave a specific segment of DNA. If however there is a base change, the restriction enzyme cannot cleave the gene as the recognition site is abolished

Question 7

Describe what a Short Tandem Repeat is

Answer 7

A microsatellite, consisting of a unit of two to thirteen nucleotides repeated hundreds of times in a row on the DNA strand

Question 8

What is the base pair change which causes Sickle Cell Disease?

Answer 8

A to T, causing a Restriction Fragment Length Polymorphism

Question 9

Map distance is measured in what units? What do they represent?

Answer 9

CentiMorgans, associated with the probability of recombination event

Question 10

Define “genetic drift”

Answer 10

Change in allele frequency by random chance

Question 11

What is the Hardy-Weinburg formula(s)?

Answer 11

p2 + 2pq + q2 = 1

p + q = 1

Question 12

Give an example of a condition which gives a heterozygous advantage to a condition

Answer 12

Sickle cell disease heterozygotes confer a survival advantage against Malaria