Mendelian inheritance

Question 1

What are the 3 laws of mendelian inheritance?

Answer 1

Law of segregation

Law of independent assortment

Law of dominance

Question 2

What is the law of segregation?

Answer 2

During gamete formation, the alleles for each gene segregate from each other

So each gamete only carries one allele for each gene

Question 3

What is the law of independent assortment?

Answer 3

Genes for different traits can segregate independently during the formation of gametes

Question 4

What is the law of dominance?

Answer 4

Some alleles are dominant while some are recessive

An organism with at least one dominant allele will display the effect of the dominant allele

Question 5

Disease X is caused by recessive allele ‘a’

An unaffected carrier father and non-carrier mother have children.

What is the risk of the children being a carrier and/or being affected?

Answer 5

No children will be affected

50% chance of child being unaffected carrier - Aa
50% chance of child being a non-carrier - AA

Question 6

Disease Y is caused by recessive allele ‘q’

Both parents are un-affected carriers

What is the risk of their children being affected/carriers etc?

Answer 6

25% chance of affected child - qq

50% chance of unaffected carrier - Qq

25% of non-carrier - QQ

Question 7

Disease E is caused by a dominant allele ‘t’

Both parents are heterozygous carriers.

What is the risk of their children being affected/carriers?

Answer 7

75% affected (25% homozygous, 50% heterozygous)

25% non carrier