Inheritance

Question 1

define gene

Answer 1

Section of DNA that codes for a characteristic

Question 2

define allele

Answer 2

The alternative forms of a gene that occur at a given point in a chromosome

Question 3

define dominant

Answer 3

it is expressed in a person who has only one copy of that gene

Question 4

define recessive

Answer 4

a trait that is expressed only when the genotype is homozygous

Question 5

define homozygous

Answer 5

Possessing the same alleles for a given characteristic

Question 6

define heterozygous

Answer 6

Possessing different alleles for a given characteristic

Question 7

define phenotype

Answer 7

The appearance of an individual determined by their genetic constitution

Question 8

define genotype

Answer 8

The genetic constitution of an individual

Question 9

what is Huntington’s disease?

Answer 9

• single gene disorder
• caused by a dominant allele
• autosomal

Question 10

what is PKU?

Answer 10

• Phenylketonuria
• recessive
• single gene
• autosomal

Question 11

how can you tell a trait is dominant?

Answer 11

• every person who shows a dominant characteristic need only have one allele for that characteristic, and every person processing such an allele must show the characteristic
• a person with a dominant characteristic must have at least one parent with the characteristic = cannot skip a generation
• two people with dominant characteristics can have a child without that characteristic
• two people who don’t possess a dominant characteristic cannot have a child with characteristic

Question 12

how can you tell a trait is recessive?

Answer 12

• every person who shows a recessive trait must have two alleles for that characteristic
• a person with a recessive trait doesn’t have to have a parent with trait = cant skip a generation
• two people without a recessive characteristic can have a child with the trait but not without

Question 13

what is haemophilia?

Answer 13

• sex linked

- due to a recessive allele on the X chromosome