Genetics And Inheritance

Question 1

What is an allele ?

Answer 1

A form of a gene, represented by either a Capital or a small letter

Question 2

What is a dominant allele ?

Answer 2

Allele is always expressed

Question 3

What is a recessive allele ?

Answer 3

Two alleles must be present for the characteristic to be expressed

Question 4

What is homozygous ?

Answer 4

And individual possesses two identical alleles for a particular gene

Question 5

What is heterozygous ?

Answer 5

Individual possesses two different alleles for a particular gene

Question 6

What is a phenotype ?

Answer 6

The feature/characteristic of an individual, coded for by their two alleles

Question 7

What is the genotype ?

Answer 7

A combination of two alleles possessed by an individual

Question 8

What is codominance ?

Answer 8

When either allele doesn’t show dominants so another characteristic is it created

Question 9

How do we work out what phenotype something will have ?

Answer 9

• Write out the genotype :
 TT    X     tt 
• Then split the chromosomes by meiosis to form gametes
[T]  [T]    X    [t]  [t]
• Foil
• this creates the genotypes
TT Tt Tt tt

Question 10

What is the carrier ?

Answer 10

A person that does not have the disease but carries a diseased allele

Question 11

What is a pedigree diagram ?

Answer 11

To show us affected and uninfected male and females in a family tree