Indicate by writing "yes" or "no" whether amplification of a signal could occur at the particular steps described below. Explain your answers
A. An extracellular signaling molecule binds and activates a GPCR.
B. The activated GPCRs cause G? to separate from G? and G?.
C. Adenylyl cyclase produces cyclic AMP.
D. cAMP activates protein kinase A.
E. Protein kinase A phosphorylates target proteins.
A. No. Each signaling molecule activates only one receptor molecule.
B. Yes. Each activated GPCR activates many G-protein molecules.
C. Yes. Each activated adenylyl cyclase molecule can generate many molecules of cAMP.
D. No. In unstimulated cells, protein kinase A is held inactive in a protein complex. Binding of cAMP to the complex induces a conformational change, releasing the active protein kinase A. Therefore, one cAMP cannot activate more than one molecule of protein kinase A.
E. Yes. Each activated protein kinase A molecule can phosphorylate many molecules of each type of target protein.
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Creutzfeldt-Jacob disease is known to have been transmitted by surgical instruments and transplanted nerve tissue.
Answer the following statement true (T) or false (F)
Tuberculoid Hansen's disease is caused by the pathogen
A) Listeria monocytogenes. B) Mycobacterium leprae. C) Mycobacterium tuberculosis. D) either Mycobacterium leprae or Mycobacterium tuberculosis.
In the example of the giant kelp forests on the Pacific coast, a rise in the otter population would have what effect on the kelp populations?
A. Kelp populations would decrease due to increased predation by otters. B. Kelp populations would increase due to an increase in sea urchins. C. Kelp populations would decrease due to an increase in sea urchins. D. Kelp populations would increase due to a decrease in sea urchins. E. Kelp populations would be totally unaffected by the otter population.
A biosphere is defined as ________ .
a. a multiceullar organism that contains nuclei b. an entire population of a species in a specified area c. a specific community interacting with its physical environment d. a group of individuals of the same species found in a given area e. the sum of all ecosystems