Question

Developmental Biology Help! Please answer all the questions

1) We discussed the fact that each stripe expression pattern is affected by the enhancer region that is utilized. Knowing that the maternal genes and the gap genes can both contribute to the pair-rule genes, and that in many cases multiple stripes may be contained in one area of GAP, how does the embryo have definition of stripes if all of these transcription factors can be within the same cell

A	it depends on which gene promoters are available due to methylation

B	none of these answers

C	it depends on which is in a higher concentration and affinity

D	it depends on which binds first

2) In relation to HOX gene expression in mammals, what would be the phenotype you expect if you had a gain of function of the sacral Hox gene center

A	the entire embryo would have only sacral regions

B	Normal Thoraic, normal lumbar, no sacral

C	Normal Thoraic, normal lumbar, normal sacral, with extra sacral at the posterior

D	Normal Thoraic, no lumbar with extra sacral, normal sacral

3) If you had a fly, that was a maternal contribution mutant (it could not provide a particular gene product for the egg) for the gene oskar, what phenotype might you expect?

A	this mutation would not have an affect on the embryo

B	only posterior tissue present

C	only middle abdomen/thoracic tissue present

D	Only dorsal tissue present

4) You have discovered a small molecule inhibitor of Gsk3-Beta Protein (GBP) which is capable of passing through a cellular membrane. To demonstrate the ability of your small molecule inhibitor you soak xenopus embryos in liquid with dissolved GBP inhibitor, however this embryo proceeds to develop head structures, however they are definitely "different" from wildtype. What is a possible conclusion from this experiment. Chose the most likely (least-pessimistic) answer.

A	my small molecule does not actually pass through the cellular membrane

B	GBP does not actually inhibit GSK3B

C	Disheveled is still present in the cells due to cortical rotation and capable inhibiting GSK3B but possibly not to the extent necessary for wildtype head formation

D	Wnt actually has nothing to do with initiation of anything

5) The purpose of the blastocoel in xenopus is to

A	provide a walkway for the migrating endoderm

B	none of these answers

C	to prevent the mesoderm from inducing the ectoderm

D	to create a separation of food from animal so it doesn't eat it all in the first couple of hours

6) A dominant negative is likely a protein version that is injected or transgenically expressed in an animal that

A	none of these answers

B	all of these answers (minus none of these answers)

C	is likely a mutant version of the wildtype target protein

D	acts to dampen the normal proteins function

E	works even though the endogenous version is working

7) The segment genes reinforce the barrier between the already forming segments by

A	by setting up the parasegment boundaries

B	none of these answers

C	using the Wnt pathway

D	using a positive feed forward loop

E	all of these answers (minus none of these answers)

8) If engrailed was not able to be expressed in the pair ruled stage of development

A	the anterior end of each segment would be lost

B	the anterior end of each parasegment would be lost

C	only every other segment would be effected

D	there would be no effect on the embryo

9)

Answer 1

Answer for question number 1)

c) it depends on which is in the higher concentration and affinity.

The homeotic transcription factor contain the DNA- binding protein region called the homeodomain. This homeodomain gene encoded by the DNA called Homeobox genes, so the homeobox gene is present the homeotic genes are called the Hox genes.

These Hox gene is turned on the protein products of the GAP genes and Pair-rule genes, so the concentration gradient which is the main cause, for the turning on of Hox genes, where the concentration is more, their the Protein is formed by the Hox gene products, to make the specific stripes in the specific region.