Cellular Communication

The termination of cell signaling requires which of the following?

• removal of the ligand
• removal of the receptor
• apoptosis
• converting of GDP to GTP

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

Epinephrine (also known as adrenaline or adrenalin) is a hormone and a neurotransmitter. The model for the action of Epinephrine is shown below.
Which of the following would likely not be observed in a person injected with epinephrine?

• Decreased production of cAMP in liver cells
• activation of phosphorylase
• Increased glucose mobilization
• Activation of G proteins

Epinephrine (also known as adrenaline or adrenalin) is a hormone and a neurotransmitter. The model for the action of Epinephrine is shown below.
Which of the following best describes a benefit of the many steps involved in a protein kinase cascade?

• It allows for the activation or inhibition of many enzymes.
• It allows for the amplification of the signal.
• It allows for the distribution of the signal throughout the inside of the cell.
•  All of the above.

Epinephrine (also known as adrenaline or adrenalin) is a hormone and a neurotransmitter. The model for the action of Epinephrine is shown below.
All of the following are enzymes involved in the signal transduction pathway shown EXCEPT

• adenyl cyclase
• protein kinase A
• phosphorylase kinase
• epinephrine

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 of the major receptors reacts by forming dimers?

• G protein coupled receptors
• ligand-gated ion channels
• steroid receptors
• receptor tyrosine kinase

When epinephrine binds to cardiac (heart) muscle cells, it speeds their contraction. When it binds to muscle cells of the small intestine, it inhibits their contraction. Which of the following best accounts for the fact that the same hormone can have different effects on muscle cells?

• Cardiac cells have more receptors for epinephrine than do intestinal cells
• Epinephrine circulates to the heart first and thus is in higher concentration around cardiac cells
• The two types of muscle cells have different signal transduction pathways for epinephrine and thus have different cellular responses
• Cardiac muscle is stronger than intestinal muscle and thus has a stronger response to epinephrine

What is a G protein?

• specific type of membrane-receptor protein
• protein on the cytoplasmic side of a membrane
• 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