2) Describe the results you expect from each of the following experiments. Descr

Question

2) Describe the results you expect from each of the following experiments. Describe any phenotype(s) you expect to see. MUST explain your reasoning.

A. Micromeres from one sea urchin embryo are transplanted to the animal pole of another sea urchin embryo.

B. Embryos of the snail Tritia are treated with cytochalasin (a drug that inhibits actin polymerization) to prevent the normal formation of their polar lobe.

C. In a 4-cell C. elegans embryo, the positions of the ABa and ABp blastomeres are reversed.

D. Transplantation of a second node in the mouse results in a duplicated axis that lacks a head.

Explanation / Answer

Ans- A the micromere, mesomere and macromere are three cells which play a crucial role in the development of sea urchin.if we transplant micromere from one sea urchin to another sea urchin then there are chances of development accurately. If the embryo cells consider it as self then the development will occur but if it is not considered as self then cell death may occur otherwise the development will not be completed in some manner.

Ans-B the polar lobe formation will be altered as the actin polymerisation will be inhibited due to which actin myosin filament will not bind properly so the development of this snail will be stoped.

Ans-C if the ABa and ABp blastomeres are reversed then the offspring produced will be fertile and the axis of the offspring will also be interchanged as the location of these blastomeres is responsible for specific cells synthesis.

Ans-D Lim1 gene is responsible for the head formation in the axis. There may be some mutation in the second node which resulted the headless axis.

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