Cell Communication & Cycle unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Signal amplification
Centrosome and spindle
Negative and positive feedback
Second messenger
Independent assortment
G1 checkpoint
Ligand
Meiosis vs mitosis
p53
G protein-coupled receptor
Signal termination
Paracrine, endocrine and synaptic signaling
Short answer 1. Define or explain: Quorum sensing
3 ptsShort answer 2. Define or explain: Meiosis I vs meiosis II
3 ptsShort answer 3. Define or explain: Chromatin vs chromosome
3 ptsShort answer 4. Define or explain: G2 and M checkpoints
3 ptsFree response
9 ptsA growth-factor signaling pathway in epithelial cells works as follows: an extracellular growth factor binds a receptor tyrosine kinase, which activates a series of relay kinases in the cytoplasm; the last kinase phosphorylates a transcription factor that turns on genes promoting progression through the cell cycle. A tumor is found to carry a receptor mutation that locks the receptor in its active conformation even when no growth factor is present.
Describe the three general stages of signal transduction as they apply to this pathway.
Explain how a phosphorylation cascade amplifies the original signal.
Predict the effect of the receptor mutation on cell division in this tissue and justify your prediction.
A drug inhibits a relay kinase downstream of the receptor. Predict whether it would slow the growth of this tumor and explain.
Explain why a drug designed to occupy the growth-factor binding site of the receptor would be ineffective against this particular tumor.