Question

Which of the following conditions would be an exception to haploinsufficiency?

	a.	Pallister-Killian syndrome
	b.	Jacobs syndrome
	c.	Turner's syndrome
	d.	Edward's syndrome
	e.	Klienfelter's syndrome

Which of the following is a likely outcome of chromosomal non-disjunction in meiosis I?

	a.	A gamete that is triploid
	b.	Four gametes that are all trisomic
	c.	A gamete that is devoid of all chromosomes
	d.	A gamete that carries both sister chromatids of one chromosome from a single parent or none at all.
	e.	A gamete that carries both homologs of one chromosome set from a single parent or none at all

Answer 1

1.Haploinsufficiency is the deletion or loss of a part or a complete gene which results in incomplete functioning of the gene. Among the given diseases all of them except Turner's syndrome are due to an extra copy of a chromosome. Only in Turner's syndrome a part or complete X chromosome goes missing due to which individuals ith turner's syndrome experience haploinsufficiency.

2. Non disjunction at meosis 1 leads to gamete that carries both sister chromatids of one chromosome from a single parent and none at all from a single parent. So option D is right. Out of the 4 gametes that are ultimately formed 2 have only one sister chromatid from one parent and 2 have 2 sister chromatids from one parent and 1sister chromatid from other parent.