2. Alleles

Question 1

Where is DNA found?

Answer 1

DNA is found in Chromosomes

Normal human cells can 23 PAIRS of CHROMOSOMES - one from mother - one from father

Question 2

What are Genes?

Answer 2

Genes are sections of DNA on a pair of Chromosome - therefore 2 copies of genes

Question 3

Ear wax is controlled by:

Answer 3

Ear wax is controlled by one gene - usually characteristics are controlled by a number of genes

Question 4

What are alleles?

Answer 4

Alleles are:

Different versions of genes eg can be short, tall

Question 5

What does the genotype of a person tells us?

Answer 5

The genotype of a person tells us the ALLELES present

Question 6

What is it called if a person has 2 copies of the SAME ALLELES?

Answer 6

If a person has 2 copies of the SAME ALLELES they are called

HOMOZYGOUS

Question 7

What is a PHENOTYPE of a person?

Answer 7

The PHENOTYPE of a person tells us:

• the CHARACTERISTICS (it is the physical appearance) caused by a person’s alleles

eg dry ear wax is ‘e’

so if you have ‘ee’ your PHENOTYPE is for dry ear wax

(Because both alleles are the same they are homozygous)

Question 8

HETEROZYGOUS is when?

Answer 8

HETEROZYGOUS is when a person has different alleles

eg ‘Ee’

Question 9

A DOMINANT allele will show in the phenotype even if only one copy is present

Answer 9

A DOMINANT allele will show in the phenotype even if only one copy is present

Question 10

A RECESSIVE allele will only show in the phenotype if:

Answer 10

A RECESSIVE allele will only show in the phenotype if

2 copies are present

Question 11

Genotype is: the combination of alleles eg bb homozygous

Answer 11

Genotype is: the combination of alleles eg bb homozygous

Question 12

Phenotype is:

Answer 12

The phenotype how the physical characteristics are shown - eg blue eyes

Question 13

2 alleles the same eg BB

Answer 13

2 alleles the same eg BB - homozygous

Question 14

Alleles different eg Bb

Answer 14

Alleles different eg Bb - HETEROZYGOUS

Question 15

Examples of Genotypes - eg BB Bb bb

Answer 15

Examples of Genotypes eg BB Bb bb

Question 16

Alleles can be:

Answer 16

Alleles can be:

Dominant or recessive

Question 17

2 features of DNA structure?

Answer 17

2 feature of a DNA structure:

• a POLYMER
• DOUBLE HELIX

Question 18

Punnett square is what?

Answer 18

Punnett square is:

Grid square diagram working out combinations of alleles

Question 19

Scientific term for a child’s eye colour is:

Answer 19

Scientific term for a child’s eye colour is:

PHENOTYPE