Topic 3 - Sex Linked Inheritance

Question 1

What are sex-linked genetic disorders?

Answer 1

Genetic disorders caused by alleles found on the sex chromosomes, X and Y.

Question 2

What is the chromosomal makeup of human males?

Answer 2

Males carry an X and a Y chromosome (XY).

Question 3

What is the chromosomal makeup of human females?

Answer 3

Females carry two X chromosomes (XX).

Question 4

Where are the majority of sex-linked conditions found?

Answer 4

On the X chromosome.

Question 5

How is an affected X chromosome represented in Punnett squares?

Answer 5

X° represents an X chromosome with the affected gene.

Question 6

How is an unaffected X chromosome represented in Punnett squares?

Answer 6

X represents an unaffected X chromosome.

Question 7

Can X-linked conditions be recessive or dominant?

Answer 7

Yes, X-linked conditions can be either recessive or dominant.

Question 8

Why are X-linked recessive syndromes more common in males?

Answer 8

Males have only one X chromosome, so if it contains the defective allele, they will have the condition.

Question 9

What is the significance of the extra X chromosome in females regarding X-linked recessive conditions?

Answer 9

It can mask the effect of the recessive allele.

Question 10

Fill in the blank: Males have _______ X chromosome(s) and _______ Y chromosome(s).

Answer 10

1 X chromosome, 1 Y chromosome

Question 11

Fill in the blank: Females have _______ X chromosome(s).

Answer 11

2 X chromosomes