AP Cell Signaling

1.  Each of the following numbered processes are involved in signal transduction pathways:  
 I.  Response  
II.  Amplification  
 III.  Reception  
IV.  Transduction
Which of the following represents the sequence of events in a typical signal transduction pathway?

• I, II, III, IV
• III, I, IV, II
• II, IV, I, III
• III, IV, II, I

All of the following statements about ligand-receptor complexes are true EXCEPT

• A. Most receptors exhibit ligand specificity.

• Ligand–receptor interactions are reversible

• Ligand–receptor interactions are shape dependent

• Ligand-receptor complexes are most often formed in cell communication pathways in which participating cells are in direct contact

Which areas in the diagram depict the process of transduction in the signal transduction pathway of cell communication?

• Q and R

• S, T, U

• Q and U

• T and U

What is a G protein?

• specific type of membrane-receptor protein

• a second messenger

• membrane-bound enzyme

• relay protein

Which of the following can activate a protein by transferring a phosphate group to it?

• cAMP
• G Protein
• protein kinase
• protein phosphatase

What do second messengers do?

• transport a signal through the lipid bilayer
• relay a signal from the outside to the inside of the cell
• relay message from the inside of the mebrane throughout the cytoplasm
• dampen the message

Signal amplification is most often achieved by

• an enzyme cascade
• binding of multiple signals
• branching pathways
• action of adenylyl cyclase

What is the mechanism of protein kinases?

• activate proteins by dephosphorylating them
• activate proteins with cAMP
• change membrane potential
• activate proteins by phosphorylating them

Testosterone does not affect all cells of the body because __________.

• testosterone cannot cross the plasma membrane

• not all cells have cytoplasmic receptors for testosterone

• not all cells in the body have membrane receptors for testosterone

• it is a local regulator

• it affects only cells that have ion-channel receptors

Estrogen, a cholesterol containing steroid hormone, does not bind to a receptor, but is still capable of crossing the cell and nuclear membranes and eliciting a response. This can occur because estrogen is

• lipophobic

• lipophilic

• a second messenger

• binds to a relay molecule inside the cell