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.
Synapsis and tetrads
Signal transduction pathway
Centrosome and spindle
Quorum sensing
Lab: Mitosis and Meiosis
Mitosis phases
Cytokinesis
Tyrosine kinase receptor
Crossing over
Cancer as checkpoint failure
Ligand
Ligand-gated ion channel
Short answer 1. Define or explain: Phosphorylation cascade
3 ptsShort answer 2. Define or explain: Sister chromatids vs homologous chromosomes
3 ptsShort answer 3. Define or explain: Apoptosis
3 ptsShort answer 4. Define or explain: Negative and positive feedback
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.