Author: Anonymous

The following happens when a G-protein-coupled receptor activates a G protein.  

You have isolated a mutant in which a fraction of the new cells die soon after cell division, and a fraction of the living cells have an extra copy of one or more chromosomes. When you grow the cells under conditions where they transit the cell cycle more slowly, the defect disappears, suggesting that the mitotic spindle and segregation machinery are normal. 1) What checkpoint may be defective in the cell cycle of the mutant? Explain your reasoning. 2) Describe in great detail the normal operation of such checkpoint.

a) Describe the checkpoint involving Rb. b) What is the phenotype of a mutant cell lacking Rb? c) What about a cell overexpressing Rb?

Which one of the following chromosomes have formed stable attachment(s) to the spindle microtubules?  

Indicate true (T) and false (F) statements below regarding signaling. Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF. (  ) Since multicellularity evolved before the divergence of the plant and animal lineages, plants have homologs of most animal signaling proteins, such as nuclear receptors, Ras, JAK, and Notch. (  ) Receptor tyrosine kinases are the largest class of cell-surface receptors in plant cells. (  ) Animals use cyclic GMP, NO, and Ca2+ for cell signaling. (  ) Receptor tyrosine kinases are the most abundant type of receptors signaling proliferation in animal cells.

The G1 DNA damage checkpoint ________________.  

Arabidopsis thaliana seedlings show positive phototropism: they bend and grow toward the source of (blue) light. However, phototropism is not observed if the seedlings are treated with an auxin efflux inhibitor called NPA. Knowing that auxin stimulates elongation of the cells in the growing shoot, these observations are consistent with a model in which, in the presence of a lateral light, …

7.  Convert 8.5 g/cm3  to  kg/m3

2.  Convert  65.3 mL to cm3

3.  Convert 15 km to meters