Fundamentals of genetics

Question 1

How would you determine the genotype of an individual with a dominant phenotype

Answer 1

a testcross - when a dominant phenotype is crossed with a true breeding recessive

Question 2

What is the ratio for mendel’s law of independent assortment

Answer 2

9:3:3:1

Question 3

What is the difference between a nonsense and a missense mutation?

Answer 3

missense - changes codon to a codon for a different amino acid

nonsense - changes a codon to a stop codon - results in truncation of protein

Question 4

Write an equation for recombination frequency

Answer 4

number of recombinant progeny/total progeny x 100

Question 5

List the genotypes for blood groups

Answer 5

Ai/AA = A
Bi/BB = B
AB = AB
ii = O

Question 6

What is non-mendelian inheritance?

Answer 6

applies to genes that are not encoded in the nucleus

Question 7

What is the purpose of Ras signalling?

Answer 7

required for differentiation and viability of all cell types in drosophila eye

Question 8

What is meant by over-dominance

Answer 8

a disease allele is present in the gene pool at higher frequencies than would be expected given the nature of the disease

Question 9

What is the difference between transitions and transversion

Answer 9

transitions - substitute purine for purine and pyramidines for pyramidines

transversions - a purine for a pyramidine

Question 10

What is meant by epistasis?

Answer 10

when two different genes contribute to a single phenotype

Question 11

What is meant by penetrance

Answer 11

the percentage of individuals with a given allele who exhibit the phenotype associated