Genetics I - Simple patterns of inheritance

Question 1

What were Mendel’s 3 ideas produced from experiments?

Answer 1

• genes + alleles
• dominant/recessive traits
• segregation of alleles

Question 2

What did Mendel refer to his proposed particles of inheritance as?

Answer 2

‘unit factors’

Question 3

What are Mendel’s ‘unit factors’ referred to today?

Answer 3

genes

Question 4

What are alleles?

Answer 4

2 copies of a gene

Question 5

What is ‘Mendel’s Law of Segregation’?

Answer 5

• 2 copies of a gene segregate from each other
• so each gamete carries only one allele

Question 6

Define phenotype

Answer 6

Characteristics that are the result of gene expression
- i.e. trait variants you see

Question 7

Define genotype

Answer 7

Genetic composition of individual
- i.e. alleles for a trait an individual carries

Question 8

What is a two-factor / two-trait cross experiment?

Answer 8

Allows you to study the inheritance of 2 different traits, to determine if genes are ‘linked’ during gamete formation.

Question 9

What is Mendel’s Law of independent assortment?

Answer 9

Alleles of different genes assort independently of each other during gamete formation

Question 10

What are gametes?

Answer 10

Haploid cells that combine to form a diploid cell (fertilisation)

Question 11

What is the wild-type allele?

Answer 11

Most prevalent allele in a population

Question 12

What are mutant alleles?

Answer 12

Altered by a change in the gene’s DNA sequence (mutation)

Question 13

Define locus

Answer 13

Physical location of a gene on a chromosome

Question 14

What do single-gene mutations cause?

Answer 14

• inherited diseases
• pleiotropic effects

Question 15

Define pleiotropy

Answer 15

Mutation in a single gene has multiple effects

Question 16

Give an example of a human disease

Answer 16

Cystic fibrosis (CF) - recessive trait