Cell Comm/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

G proteins are a family of proteins involved in transmitting chemical signals originating from outside a cell into the inside of the cell. G proteins function as molecular switches.
Which of the following best describes the role in which the G protein is most intimately involved in the process shown above?

• Production of the ligand molecule.
• Reception of the signal.
• Transduction of the signal.
• Production of response to signal.

The term steroid describes both hormones produced by the body and artificially produced medications that duplicate the action for the naturally occurring steroids. All of the following describe steroid hormones EXCEPT:

• A.  They bind with receptor proteins in the plasma membrane to trigger cellular responses.
• A.  They are derived from cholesterol and are lipid soluble.
• They serve as ligands in signal transduction pathways
• A.  They are exemplified by testosterone, estrogen and progesterone

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

Cell signaling involves converting extracellular signals to specific responses inside the target cell. Which of the following best describes how a cell initially responds to a signal?

• The cell experiences a change in receptor conformation
• The cell experiences an influx of ions
• The cell experiences an increase in protein kinase activity
• The cell experiences G protein activation

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

• Q and R
• Q and U
• S and T
• T and U

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 does a protein phosphatase do?

• removes phosphates
• transfers phosphates from ATP to proteins
• activates an enzyme with a signal molecule