Inheritance

Question 1

define genotype

Answer 1

genetic constitution of an organism

Question 2

define phenotype

Answer 2

expression of this genetic Constitution and it’s interaction with the environment

Question 3

what are alleles and how do they arise

Answer 3

variation of a particular gene and arise by mutation

Question 4

How many alleles of a gene can be found in diploid organisms?

Answer 4

2 as diploid organisms have 2 sets of chromosome

-but there may be many alleles of a single gene

Question 5

Describe the different types of alleles

Answer 5

-Dominant : alleles is always expressed

-recessive : alleles are only expressed if there is no dominant allele / two copies are present

-Codominant : both alleles are equally expressed and dominant

Question 6

What is meant by the terms homozygous and heterozygous?

Answer 6

Homozygous : alleles at the specific locus ( on the homologous chromosome) are the same

Heterozygous : alleles as specific locus ( on the homologous chromosome ) are different

Question 7

What is a sex-linked gene?

Answer 7

A gene with a locus on a sex-chromosome (normally X)

Question 8

Explain why males are more likely to express a recessive X-linked allele

Answer 8

● Females (XX) have 2 alleles → only express recessive allele if homozygous recessive / can be carriers
● Males (XY) have 1 allele (inherited from mother) → recessive allele always expressed