Question

Bob and Mary both suffer from Sickle Cell Disease, an autosomal recessive condition (they have the condition - they are not just carriers). They met in a support group and against their doctor's advice, decide to have a child. What is the probability that their child will NOT have Sickle Cell Disease?

		33%
		0%
		75%
		50%
		25%

1. The _____ checkpoint can only be passed if the right growth factors have been received from other cells

   		G1/S
   		G2
   		G2/M
   		S

The protein hemoglobin, which carries oxygen in red blood cells, is a protein complex that consists of 4 separate subunits encoded by 2 genes: One gene encodes the two alpha-globin subunits while the other encodes the two beta-globin subunits. Four functional subunits (2 of each kind) are needed for a functional complex.

If a person carries just one mutant allele for alpha-globin, any complexes containing a copy of the mutant protein are nonfunctional, even if the other alpha-globin subunit is normal. As a result, almost all the hemoglobin produced is nonfunctional.

This is an example of a      mutation.

		leaky / hypomorphic
		gain of function / neomorphic
		gain of function / hypermorphic
		dominant negative / antimorphic

What gametes are possible from the parental genotype XXYyZz?

SELECT ALL THAT APPLY, but be aware that incorrect choices count against you.

		XYZ
		XYz
		XyZ
		xYZ
		xxyyzz
		xYz
		Xyz
		xyz

Answer 1

Question 1:-

The right option is option (B) 0%

Explanation:-

Sickle cell anemia is a Recessive disorder which means that for an individual to have the disease, they need to have both the copies of the Gene defective with the mutant form. Now everyone have 2 allele copy for autosomal genes. Both Bob and Mary have the disease which mean that both of them have both of their allele as sickle cell anemia.

No one from them have a healthy gene copy. This mean there's no possible combination of their gametes which will have a healthy allele. So the their chances of having a healthy, normal baby are 0%

Question 2:-

The right option is option (A) G1/S

Explanation:-

The most important check point in several organism is the G1 checkpoint as once the cell moves forward, it almost irreversibly commits itself to the cell cycle. Thus, this is the restriction point and this check point is controlled by different factors which also includes Growth factors.

Question 3:-

The right option is option (D) Dominant negative/antimorphic

Explanation:-

There are two types of alleles, one are Recessive and other negative. For a Recessive allele to show a phenotype the requirement is that both the allele copies should be mutant/recessive form.

While in dominant alleles, One copy of mutant form is enough to show the phenotype. This mean that one copy of Mutant can mask the effect of Wild type allele and make all the other wild type redundant.

That's what happening in this case too with just one defective polypeptide out of 4 polypeptide is enough to destroy the RBC. Hence it is dominant negative.

Question 4:-

The right options are :-

XYZ

XYz

XyZ

Xyz

Explanation:-

To find all the possible combination of gametes, we have to consider the alleles present in the autosomes.

Now if we look the genotype is XX Yy Zz

Now there's only X allele present for X

For Y, two allele are present Y and y

For Z, two alleles are present Z and z.

Now there can be only X in gametes as only one allele is present. There can be Y or y, meaning the combination are XY and Xy. Now for Z too, the combination are XYZ, XyZ, XYz, Xyz.