7A- Genetics

Question 1

Gene

Answer 1

A sequence of bases on a DNA molecules that codes for a protein (polypeptide) which results in a characteristic (eg a gene for eye colour)

Question 2

Allele

Answer 2

A different version of a gene. Can be many different alleles of a single gene, but most plants and animals only carry two allies of each gene, one from each parent. They code for different versions of the same characteristic

Question 3

Genotype

Answer 3

The genetic constitution of an organism- the alleles an organism has

Question 4

Phenotype

Answer 4

The expression of the genetic constitution and its interaction with the environment- an organisms characteristics

Question 5

Dominant allele

Answer 5

An allele whose characteristic appears in the phenotype even when there’s only one copy. Dominant alleles are shown by a capital letter

Question 6

Recessive alleles

Answer 6

An allele whose characteristic only appears in the phenotype if two copies are present. Recessive alleles are shown by a lower case letter

Question 7

Codominant

Answer 7

Alleles that are both expressed in the phenotype- neither one is recessive

Question 8

Locus

Answer 8

The fixed position of a gene on a chromosome. Alleles of a gene are found at the same locus on each chromosome in a pair

Question 9

Homozygote

Answer 9

An organism that carries two copies of the same allele

Question 10

Heterozygote

Answer 10

An organism that carries two different alleles

Question 11

Carrier

Answer 11

A person carrying an allele which is not expressed in the phenotype but that can be passed on to offspring