Lecture 5

Question 1

Multiple alleles

Answer 1

When more than two alternatives are possible for a gene locus
eg. tabby cat, clover

Question 2

Phenocopy

Answer 2

Phenotypic copy: a copy of an inherited condition but results from an environmental factor… occurs when the environment modifies the phenotype to mimic the effect of a specific genotype
eg. Meromelia

Question 3

Pleiotropy

Answer 3

A single gene may affect many features of the phenotype. Single mutation, many effects
eg. Sickle cell anaemia, albinism

Question 4

Variable expression

Answer 4

the degree or range in which a particular phenotype is expressed by individuals
eg. Mild, moderate, severe

Question 5

Reduced pentrance

Answer 5

• the proportion of genotypes that show the expected phenotype
• May not have it show up even if it is in their genotype
• -> can be determined by environment (temperature)

Question 6

Lethality

Answer 6

a combination of alleles that result in death at some point in the life span

• Recessive lethal –> kills in the homozygote eg. aa or BB
• Dominant lethal –> kills in homo and heterozygote