L 12

Question 1

What sex would XXY?

Answer 1

Male

Question 2

What sex would XO be?

Answer 2

Female

Question 3

Is all of the Y- chromosome required to confer maleness?

Answer 3

No only the SRY (sex-deterring region on Y) gene is required

Question 4

A person was found to have XY chromosomes, but the SRY gene in Y was mutated? What is the sex of this person?

Answer 4

This would be a female, as SRY must be functional to determine sex

Question 5

A person whos sex chromosome were XX, had a translocation of SRY gene into X chromosome, what is the sex of this person?

Answer 5

Male

Question 6

How does SRY confer maleness?

Answer 6

It is believed that it is a transcription factor responsible for the formation of testes

Question 7

What is the SEX DETERMINATION chromosomes in birds?

Answer 7

Male = ZZ
Female = ZY

Question 8

Why are x-linked disease more common in males?

Answer 8

because they are hemizygous

Question 9

Name X-linked-conditions. (3)

Answer 9

• haemophilia A and B
• Duchenne muscular hypertrophy
• Red-green colour blind

Question 10

What are Barr bodies?

Answer 10

inactive X chromosomes in FEMALES

Question 11

X-linked traits obviously affect X, chromosomes, in females x- chromosomes are 2 (XX), therefore the trait should manifest 2x stronger, how is this prevented?

Answer 11

This is prevented by X- chromosome inactivation, which are called Barr bodiess