1. In your own words, define the following terms
- protein-tyrosine kinase
- cAMP
- paracrine signaling
- hormone
- RAS-MAP kinase cascade
- GTPase-activating proteins (GAPs)
- caspase
- second messenger
2. Compare and contrast microtubule assembly and intermediate filament assembly (300-350 words)
3. How is it possible for the same vesicle to be transported along both microtubules and microfilaments? Describe how this process applies to pigment cells and what occurs when this process is defective in those cells. (200-250 words)
4. How can different cells respond in different ways to exactly the same molecules even when these molecules are binding to the same receptors? Provide an example of this phenomenon. (150-200 words)
5. For each of the following statements: 1) Decide whether the statement is true or false and 2) Explain your answer in 50-100 words
a. Both the GTP-bound α-subunits and the nucleotide-free βγ subunits (but NOT the GDP-bound, fully assembled heterotrimeric G protein) can activate other molecules downstream of GPCRs.
b. Once bound to arrestin, GPCRs are incapable of activating downstream targets.
c. Activation of myosin movement on actin filaments is triggered by the phosphorylation of troponin in some situations and by Ca2+ binding to troponin in others.
d. All second messengers are water soluble and diffuse freely through the cytosol.