1. In your own words, define the following terms
- protein-tyrosine kinase- phosphorylate proteins from ATP molecules
- cAMP- cyclic adenosine mono phosphate, usually initiates feed back looks in biological reactions
- paracrine signaling- cell to cell interactions, usually promote a sory of signaling cascade in biosynthetic pathways
- hormone-endocrine signaling molecules
- RAS-MAP kinase cascade - a type of rtk signaling that activates a large signaling cascade resulting in initiation of nuclear transcription factors
- GTPase-activating proteins (GAPs)- eznymes that are notorious for their involvememnt in cell signaling
- Caspase- protease enzymes that are involved in promoting cell apoptosis
- second messenger- molecules that send signals down a signaling cascade that are not the original activation complex
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.
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.