Introduction to genetics

Question 1

How many pairs of chromosomes does a human have?

Answer 1

23 pairs

Question 2

What are the 2 components of a phenotype?

Answer 2

Genetics + environment

Question 3

What are the 3 main classes of genetic disease?

Answer 3

Monogenic
Multifactorial
Chromosomal

Question 4

Cystic fibrosis is an example of what class of genetic disease?

Answer 4

Monogenic

Question 5

Heart disease is an example of what class of genetic disease?

Answer 5

Multifactorial

Question 6

Down’s syndrome is an example of what class of genetic disease?

Answer 6

Chromosomal

Question 7

In regards to alleles, what is the ‘wild type’?

Answer 7

The allele that is most common in a population

Question 8

What are Mendel’s 3 laws of inheritance?

Answer 8

Law of uniformity
Law of segregation
Law of independent assortment

Question 9

What is consanguinity?

Answer 9

The degree of genetic relatedness or shared ancestry between individuals

Question 10

Which blood group is recessive?

Answer 10

O

Question 11

What is overdominance?

Answer 11

Where homozygotes experience more severe consequences than heterozygotes, often leading to incompatibility with life

Question 12

What is incomplete penetrance?

Answer 12

Not all individuals with a disease causing genotype exhibit the disease clinically

Question 13

What is genomic imprinting?

Answer 13

When the expression of a gene depends on whether it is inherited from the mother or father

Question 14

What is mitochondrial inheritance?

Answer 14

Genes located in the mitochondria are inherited solely from the mother

Question 15

What is genetic linkage?

Answer 15

Genes located close together on the same chromosome tend to be inherited together

Question 16

What is dynamic mutation?

Answer 16

Genetic diseases occur with increasing severity in consecutive generations, due to expansion of a repetitive DNA sequence

Question 17

In X-linked inheritance, what risks would an unaffected male mating with a carrier female produce for sons + daughters?

Answer 17

Daughters - 50% carrier risk

Sons - 50% affected risk

Question 18

In X-linked inheritance, what risks would an unaffected female mating with an affected male produce for sons + daughters?

Answer 18

Daughters - 100% carrier risk

Sons - 100% unaffected

Question 19

List 3 X-linked diseases.

Answer 19

Haemophilia A
Red / green colour blindness
Duchenne muscular dystrophy

Question 20

What is mosaicism?

Answer 20

Different cells within the same individual have different genotypes