Question 1

The signals that bind to receptors on nearby cells are known as

Accepted Answer

A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  hormones. 
E)  responders. 
A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  hormones. 
E)  responders.

Question 2

Increased synthesis of phosphodiesterase would lead to

Accepted Answer

A)  decreased concentration of cyclic AMP. 
B)  increased concentration of cyclic AMP. 
C)  increased concentration of calmodium. 
D)  decreased concentration of calmodium. 
E)  inhibition of adenylyl cyclase. 
A)  decreased concentration of cyclic AMP. 
B)  increased concentration of cyclic AMP. 
C)  increased concentration of calmodium. 
D)  decreased concentration of calmodium. 
E)  inhibition of adenylyl cyclase.

Question 3

Gap junctions

Accepted Answer

A)  allow large molecules and ions to pass rapidly between cells. 
B)  permit metabolic cooperation among linked cells. 
C)  are formed by the peripheral membrane protein connexin. 
D)  are present in many copies per cell. 
E)  contain membrane lined bridges. 
A)  allow large molecules and ions to pass rapidly between cells. 
B)  permit metabolic cooperation among linked cells. 
C)  are formed by the peripheral membrane protein connexin. 
D)  are present in many copies per cell. 
E)  contain membrane lined bridges.

Question 4

Chemical signal transduction pathways

Accepted Answer

A)  use non-specific receptors. 
B)  involve binding of the signal molecule to receptors. 
C)  use receptors that are located only on the plasma membrane. 
D)  always result in increased transcription of a gene. 
E)  all use G proteins. 
A)  use non-specific receptors. 
B)  involve binding of the signal molecule to receptors. 
C)  use receptors that are located only on the plasma membrane. 
D)  always result in increased transcription of a gene. 
E)  all use G proteins.

Question 5

Trace how changes in osmotic pressure in the plasma membrane of E. coli result in changes in gene transcription. What would be the outcome if OmpR could not bind to the ompC promoter?

Accepted Answer

Refer to Figure 7.3 in the textbook. If

Question 6

Which of the following statements about cyclic AMP is false?

Accepted Answer

A)  It can bind to, and thus open, ion channels in some sensory cells. 
B)  In some circumstances it can bind to a protein kinase in the cytoplasm. 
C)  The enzyme adenylyl cyclase catalyzes its formation from ATP. 
D)  It is a second messenger. 
E)  It has enzymatic activity. 
A)  It can bind to, and thus open, ion channels in some sensory cells. 
B)  In some circumstances it can bind to a protein kinase in the cytoplasm. 
C)  The enzyme adenylyl cyclase catalyzes its formation from ATP. 
D)  It is a second messenger. 
E)  It has enzymatic activity.

Question 7

Signals that diffuse to and affect nearby cells are known as _______ signals.

Accepted Answer

The answer of Signals that diffuse to and affect nearby...

Question 8

In what way do ligand-receptor interactions differ from enzyme-substrate reactions?

Accepted Answer

A)  The ligand signal is not usually metabolized into useful products. 
B)  Receptor-ligand interactions do not obey the laws of mass action. 
C)  Inhibitors never bind to the ligand-binding site. 
D)  Reversibility never occurs in the ligand-receptor interaction. 
E)  The enzyme-substrate reaction and the ligand-receptor interaction do not differ. 
A)  The ligand signal is not usually metabolized into useful products. 
B)  Receptor-ligand interactions do not obey the laws of mass action. 
C)  Inhibitors never bind to the ligand-binding site. 
D)  Reversibility never occurs in the ligand-receptor interaction. 
E)  The enzyme-substrate reaction and the ligand-receptor interaction do not differ.

Question 9

If a G protein were unable to release its bound nucleo­tide but could hydrolyze it, signal transduction would

Accepted Answer

A)  cease. 
B)  be continuous. 
C)  be unaffected. 
D)  be constantly switching on and off. 
E)  be unpredictable. 
A)  cease. 
B)  be continuous. 
C)  be unaffected. 
D)  be constantly switching on and off. 
E)  be unpredictable.

Question 10

Which of the following strongly binds to the acetylcholine receptor?

Accepted Answer

A)  Estrogen 
B)  Acetylcholine 
C)  Sodium 
D)  OmpC 
E)  Protein kinases 
A)  Estrogen 
B)  Acetylcholine 
C)  Sodium 
D)  OmpC 
E)  Protein kinases

Question 11

Which of the following statements is false?

Accepted Answer

A)  Plants respond to light as a signal. 
B)  The environment experienced by a cell deep inside a large multicellular organism is very different from the external environment. 
C)  Some plants are capable of responding to temperature fluctuations. 
D)  Some cells can self-stimulate cell division by making their own division signals. 
E)  None of the above 
A)  Plants respond to light as a signal. 
B)  The environment experienced by a cell deep inside a large multicellular organism is very different from the external environment. 
C)  Some plants are capable of responding to temperature fluctuations. 
D)  Some cells can self-stimulate cell division by making their own division signals. 
E)  None of the above

Question 12

Phosphorylation changes the _______ and _______ of a protein.

Accepted Answer

The answer of Phosphorylation changes the _______ and _______ of...

Question 13

Which of the following is not a response to a signal binding its receptor?

Accepted Answer

A)  A channel opening 
B)  A G protein's exchange of GDP for GTP 
C)  Increase in intracellular concentration of nitrous oxide 
D)  The diffusion of solutes through the porous outer membrane of E. coli 
E)  Activation of a protein kinase 
A)  A channel opening 
B)  A G protein's exchange of GDP for GTP 
C)  Increase in intracellular concentration of nitrous oxide 
D)  The diffusion of solutes through the porous outer membrane of E. coli 
E)  Activation of a protein kinase

Question 14

Which of the following is true about EnvZ?

Accepted Answer

A)  It phosphorylates itself during signal transduction. 
B)  It has domains on both the inside and the outside of the cell. 
C)  It acts as a responder. 
D)  Both a and b 
E)  All of the above 
A)  It phosphorylates itself during signal transduction. 
B)  It has domains on both the inside and the outside of the cell. 
C)  It acts as a responder. 
D)  Both a and b 
E)  All of the above

Question 15

Caffeine mimics the molecular structure of

Accepted Answer

A)  paracrine. 
B)  aspirin. 
C)  adenosine. 
D)  autocrine. 
E)  None of the above 
A)  paracrine. 
B)  aspirin. 
C)  adenosine. 
D)  autocrine. 
E)  None of the above

Question 16

The first component of a signal transduction pathway is a(n)

Accepted Answer

A)  paracrine molecule. 
B)  responder. 
C)  receptor. 
D)  hormone. 
E)  effector molecule. 
A)  paracrine molecule. 
B)  responder. 
C)  receptor. 
D)  hormone. 
E)  effector molecule.

Question 17

After the GTP-bound subunit of the G protein separates from the rest of the G protein, it travels until it encounters

Accepted Answer

A)  an activator. 
B)  a receptor. 
C)  an effector protein. 
D)  a protein kinase. 
E)  another G protein. 
A)  an activator. 
B)  a receptor. 
C)  an effector protein. 
D)  a protein kinase. 
E)  another G protein.

Question 18

The signals that bind to receptors of the same cell that made them are known as

Accepted Answer

A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  hormones. 
E)  responders. 
A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  hormones. 
E)  responders.

Question 19

Signaling proteins that are characterized by their ability to bind GTP and GDP are known as _______ proteins.

Accepted Answer

The answer of Signaling proteins that are characterized by their...

Question 20

Which of the following statements about receptors is true?

Accepted Answer

A)  Receptors are only found on the surface of cells. 
B)  Receptors are specific to the signal ligand. 
C)  Most receptors can bind with many signal ligands. 
D)  All receptors can act as ion channels. 
E)  All of the above 
A)  Receptors are only found on the surface of cells. 
B)  Receptors are specific to the signal ligand. 
C)  Most receptors can bind with many signal ligands. 
D)  All receptors can act as ion channels. 
E)  All of the above

Exam 7: Cell Signaling and Communication

The signals that bind to receptors on nearby cells are known as

Increased synthesis of phosphodiesterase would lead to

Gap junctions

Chemical signal transduction pathways

Trace how changes in osmotic pressure in the plasma membrane of E. coli result in changes in gene transcription. What would be the outcome if OmpR could not bind to the ompC promoter?

Which of the following statements about cyclic AMP is false?

Signals that diffuse to and affect nearby cells are known as _______ signals.

In what way do ligand-receptor interactions differ from enzyme-substrate reactions?

If a G protein were unable to release its bound nucleo­tide but could hydrolyze it, signal transduction would

Which of the following strongly binds to the acetylcholine receptor?

Which of the following statements is false?

Phosphorylation changes the _______ and _______ of a protein.

Which of the following is not a response to a signal binding its receptor?

Which of the following is true about EnvZ?

Caffeine mimics the molecular structure of

The first component of a signal transduction pathway is a(n)

After the GTP-bound subunit of the G protein separates from the rest of the G protein, it travels until it encounters

The signals that bind to receptors of the same cell that made them are known as

Signaling proteins that are characterized by their ability to bind GTP and GDP are known as _______ proteins.

Which of the following statements about receptors is true?

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If a G protein were unable to release its bound nucleotide but could hydrolyze it, signal transduction would

Phosphorylation changes the _ and _ of a protein.