ESSENTIAL CELL BIOLOGY CHAPTER
#16-CELL SIGNALING EXAM
QUESTIONS WITH CORRECT ANSWERS
What is a neurotransmitter? - ANSWER-a chemical that travels from one neuron to
another through diffusion across a synapse
What is characteristic about contact-dependent signaling? (2) - ANSWER--the most
intimate and short-range of all signaling
-cells make direct physical contact through signal molecules lodged in the plasma
membrane of the signaling cell and receptors in the target cell
what process uses contact-dependent signaling? - ANSWER-cell differentiation in
embryonic development
Whether a cell responds to a signal molecule depends on what? - ANSWER-whether it
has a receptor for that molecule
What are the 2 categories of receptors? (in terms of location) Which is the largest? -
ANSWER--cell-surface receptors--the largest
-intracellular receptor molecules
What is characteristic of cell-surface signaling molecules? (2) - ANSWER--too large or
too hydrophilic to cross the membrane
-rely on receptors in the surface of the target cell
What is characteristic of intracellular signaling molecules? (2) - ANSWER--small enough
or hydrophobic enough to cross the membrane
-bind to intracellular receptor proteins in the cell's cytosol
what are effector proteins? - ANSWER-proteins that have some direct effect on the
behavior of the target cell due to cell-cell signaling
How can 2 different cells respond to the same signal in different ways? - ANSWER-a
cell's intracellular relay system and the activity of effector proteins alter a cell's behavior
in different ways by differing from cell to cell
How do different combinations of signals impact cell behavior? - ANSWER-different
combinations of signals cause intracellular relay systems which will then interact making
one signal modify the effects of another to produce a characteristic response
the absence of signals often results in what? - ANSWER-cell death
, A cell's response to a signal can be fast or slow. Explain this in terms of ACh and cell
growth and division - ANSWER--ACh is a signal that can stimulate cells like muscle
cells or salivary glands very quickly because it activates proteins that are already
present inside the cell
-cell growth and division take more time because they require changes in gene
expression and the production of new proteins
The majority of extracellular signal molecules are what 3 things? - ANSWER-proteins,
peptides, or small, hydrophilic molecules
Describe the process of extracellular signaling in terms of it being a relay race. What are
the 3 possible outcomes of this? - ANSWER--the extracellular signal molecule binds to
a receptor on the cell's plasma membrane
-different intracellular signaling molecules are activated one by one in a "relay"
-this process continues until a metabolic enzyme is kicked into action, a cytoskeleton is
tweaked, or a gene is switched on or off
What are 5 things that intracellular signaling molecules do in the cell after being
activated? - ANSWER--they relay the message
-they can transduce and amplify the signal
-the can integrate signals from one or more intracellular signaling pathway
-they can provide feedback on the activity of the cell
-they can distribute a signal to more than one effector protein
How do intracellular signaling molecules play a role in positive or negative feedback? -
ANSWER--positive: a component that lies downstream in the pathway acts on an earlier
component to enhance the response to the initial signal
-negative: a downstream component acts to inhibit an earlier component in the pathway
to diminish the response to the initial signal
what is a molecular switch? - ANSWER-intracellular signaling proteins that receive a
signal which causes them to toggle from inactive to active; they will persist in this active
state until some other process switches them off again
for every activation step in the pathway there must be an inactivation step T/F -
ANSWER-True
molecular switches fall into one of two classes. What are the two classes and which is
the largest? - ANSWER--proteins activated or inactivated by phosphorylation--largest
-proteins activated by GTP-binding proteins
what 2 proteins are essential in phosphorylation? - ANSWER--protein kinases: add a
phosphate group
-protein phosphatase: takes the phosphate off
phosphorylation of a protein can activate it OR inhibit it T/F - ANSWER-True
#16-CELL SIGNALING EXAM
QUESTIONS WITH CORRECT ANSWERS
What is a neurotransmitter? - ANSWER-a chemical that travels from one neuron to
another through diffusion across a synapse
What is characteristic about contact-dependent signaling? (2) - ANSWER--the most
intimate and short-range of all signaling
-cells make direct physical contact through signal molecules lodged in the plasma
membrane of the signaling cell and receptors in the target cell
what process uses contact-dependent signaling? - ANSWER-cell differentiation in
embryonic development
Whether a cell responds to a signal molecule depends on what? - ANSWER-whether it
has a receptor for that molecule
What are the 2 categories of receptors? (in terms of location) Which is the largest? -
ANSWER--cell-surface receptors--the largest
-intracellular receptor molecules
What is characteristic of cell-surface signaling molecules? (2) - ANSWER--too large or
too hydrophilic to cross the membrane
-rely on receptors in the surface of the target cell
What is characteristic of intracellular signaling molecules? (2) - ANSWER--small enough
or hydrophobic enough to cross the membrane
-bind to intracellular receptor proteins in the cell's cytosol
what are effector proteins? - ANSWER-proteins that have some direct effect on the
behavior of the target cell due to cell-cell signaling
How can 2 different cells respond to the same signal in different ways? - ANSWER-a
cell's intracellular relay system and the activity of effector proteins alter a cell's behavior
in different ways by differing from cell to cell
How do different combinations of signals impact cell behavior? - ANSWER-different
combinations of signals cause intracellular relay systems which will then interact making
one signal modify the effects of another to produce a characteristic response
the absence of signals often results in what? - ANSWER-cell death
, A cell's response to a signal can be fast or slow. Explain this in terms of ACh and cell
growth and division - ANSWER--ACh is a signal that can stimulate cells like muscle
cells or salivary glands very quickly because it activates proteins that are already
present inside the cell
-cell growth and division take more time because they require changes in gene
expression and the production of new proteins
The majority of extracellular signal molecules are what 3 things? - ANSWER-proteins,
peptides, or small, hydrophilic molecules
Describe the process of extracellular signaling in terms of it being a relay race. What are
the 3 possible outcomes of this? - ANSWER--the extracellular signal molecule binds to
a receptor on the cell's plasma membrane
-different intracellular signaling molecules are activated one by one in a "relay"
-this process continues until a metabolic enzyme is kicked into action, a cytoskeleton is
tweaked, or a gene is switched on or off
What are 5 things that intracellular signaling molecules do in the cell after being
activated? - ANSWER--they relay the message
-they can transduce and amplify the signal
-the can integrate signals from one or more intracellular signaling pathway
-they can provide feedback on the activity of the cell
-they can distribute a signal to more than one effector protein
How do intracellular signaling molecules play a role in positive or negative feedback? -
ANSWER--positive: a component that lies downstream in the pathway acts on an earlier
component to enhance the response to the initial signal
-negative: a downstream component acts to inhibit an earlier component in the pathway
to diminish the response to the initial signal
what is a molecular switch? - ANSWER-intracellular signaling proteins that receive a
signal which causes them to toggle from inactive to active; they will persist in this active
state until some other process switches them off again
for every activation step in the pathway there must be an inactivation step T/F -
ANSWER-True
molecular switches fall into one of two classes. What are the two classes and which is
the largest? - ANSWER--proteins activated or inactivated by phosphorylation--largest
-proteins activated by GTP-binding proteins
what 2 proteins are essential in phosphorylation? - ANSWER--protein kinases: add a
phosphate group
-protein phosphatase: takes the phosphate off
phosphorylation of a protein can activate it OR inhibit it T/F - ANSWER-True
