AP BIO - Cell Communication Exam Review

A toxin that destroys adenylyl cyclase, the enzyme responsible for creating cyclic AMP—a second messenger molecule in the cell – is injected into a cell.  What will be the final effect on the signaling pathway?

• The initial messenger molecule (ex: epinephrine) will be unable to bind to its plasma membrane receptor.

• The initial messenger molecule (ex. epinephrine) will bind more easily to the plasma membrane receptor.

• The transduction step will be inhibited, resulting in a smaller or absent cell response.

• The transduction step will be more efficient, resulting in a larger response.

If ATP is not present in the cell pictured, what would be the most immediate effect on the receptor tyrosine kinase pathway?

• The signal molecules would not be able to bind to the receptor.

• The tyrosine molecules will be unable to detach from the receptor.

• The tyrosine molecules will not be able to "steal" phosphate groups from ATP and use these phosphate groups to activate other proteins.

• The two units of the receptor will not be able to come together as a dimer (two polypeptide chain protein).

The pathway pictured shows the effect of insulin, a hormone released in response to high blood glucose, on liver cells.  In Type 1 diabetes, cells in the pancreas cannot create and secrete insulin.  How will this affect blood glucose levels?

• Blood glucose levels will remain high because glucose will not be removed from the blood by the GLUT channels in liver cells.

• Blood glucose levels will decrease because glucose will be successfully removed from the blood by the GLUT channels in liver cells.

• Blood glucose levels will remain high because the pancreas will never receive the signal to create insulin.

• Blood glucose levels will decrease because the receptor will be activated by another hormone.

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NGSS.HS-LS1-3

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to:

• the active site of an enzyme in the cytoplasm that binds to a specific substrate.

• RNA specifying the amino acids in a polypeptide.

• a particular metabolic pathway operating within a specific organelle.

• genes making up a chromosome.

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?

• Estrogen is produce in very large concentration and therefore diffuses widely.

• Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding.

• Estrogen is kept away from the surface of any cells not able to bind it at the surface.

• Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding.

• Estrogen has different shaped receptors for each of several cell types.

Which of these is a common type of final response in a signal transduction pathway?

• Activation of a G-protein receptor

• Transcription of a desired mRNA sequence

• Formation of cAMP

• Phosphorylation cascade

Which of the following is a characteristic of cell signaling pathways?

• They are irreversible.

• They only occur outside the cell.

• They can amplify the signal received by the cell.

• They reduce the specificity of the signal.

What are the three parts of signal transduction pathway?

• reception, transduction, response

• confirmation, transduction, transcription

• reception, amplification, transcription

• confirmation, amplification, response

Transduction step traditionally amplifies the signal, which of the following are NOT involved with transduction?

• secondary messengers

• protein modification

• phosphorylation cascade

• ligands

If a medicine works by blocking a secondary messenger, what effect would it have on that cell signaling pathway?

• It would increase the response if the pathway

• It would trigger the release of more ligands

• It would activate the transcription of a desired gene

• It would inhibit transduction, thus deactivating the response