1 A cell does not have the sister chromatids properly attach

1. A cell does not have the sister chromatids properly attached to the spindle fibers. What statement would be true for this cell:

A. it would be stuck in G1 phase
B. it would be stuck in S phase
C. It would be stuck in G2 or early M phase
D. It would not complete mitosis
E. more than one of the above answers is correct

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2. Platelet derived growth factor and insulin have all of the following in common EXCEPT:

A. They both bind to membrane-bound receptors
B. They both trigger a signal transduction pathway inside the cell
C.  They both trigger pathways that involve phosphorylations
D. All of the above are true for both insulin and PDGF

Solution

1). D. It would not complete mitosis

The Mad or Bub proteins are the spindle checkpoint genes and are involved in the regulation of cell cycle by halting the cell cycle till all the chromosomes align at the metaphase plate. The improper assembly of spindle fibres trigger the spindle assembly checkpoint signal (SAC), which inhibits the cell cycle by the negative regulation of CDC20 and inhibit the polyubiquitylation activation of APC (anaphase-promoting complex).