BIOL 1201: FINAL EXAM QUESTIONS
AND ANSWERS (GRADED A+)
What are the three types of cell signaling? - ANSWER-1. Direct Contact
2. Local
3. Distant
Describe direct contact cell signaling and some examples. - ANSWER-One cell actually
physically touches another
i.e. Gap Junctions (diffusion of signals through a plasma membrane), Plasmodesmata
(diffusion of signals through a plasma membrane), and Cell-Cell Recognition (one cell
have a type of signal molecule while the other cell has a receptor, and they bind and
create a response)
Describe local cell signaling and some examples. - ANSWER-Cells are signaling and
the signal is released into the extracellular liquid; affects cells in the area
i.e. Paracrine (one cell is releasing signal molecules, diffusing into the area, affecting
the cells nearby, for example, a wound) and Synaptic (space between neurons where
neurotransmitters diffuse across the synapsis)
Describe distant cell signaling and some examples. - ANSWER-Signals cells in another
part of the body
i.e. Endocrine System (hormones are sent all over the body to initiate a response)
A compound that is secreted in one part of the body and travels through the
bloodstream to another part of the body where it has an effect is called a(n)
A. Receptor protein
B. Hormone
C. Transmitter
D. Activator - ANSWER-B. Hormone
When a platelet contacts a damaged blood vessel, it is stimulated to release
thromboxane A2. Thromboxane A2 in turn stimulates a vascular spasm and attracts
additional platelets to the injured site. In this example, thromboxane A2 is acting as
____________.
A. direct contact signal molecule
B. local signal molecule
C. distant signal molecule - ANSWER-B. local signal molecule
,What are the three steps of cell signaling? - ANSWER-1. Reception
2. Transduction
3. Response
Where are receptors located? - ANSWER-plasma membrane and cytoplasm
Most receptors are _____________ attached to the plasma membrane. - ANSWER-
proteins
Since receptors are proteins, what does that tell us about the specificity of the
receptors? - ANSWER-Since receptors are proteins, then they are highly specific and
will only bind to a specific signal molecule.
Which molecules determine the tissue specificity of hormones?
A. Receptors.
B. Hormone-response elements.
C. Second messengers.
D. Agonists. - ANSWER-A. Receptors.
Assuming there are a 100 different signaling molecules in your body. What is the
minimum number of receptors that your body needs to make?
A. 1
B. 10
C. 100
D. 1000
E. 1000000 - ANSWER-C. 100
The signal molecule Leptin is 16000 Da protein. Where would you expect to find the
receptors of this molecule?
A. cytoplasm
B. cell membrane
C. I don't know - ANSWER-B. cell membrane
Protein signal molecules are not permeable to the cell membrane but can affect their
target cells because
A. intracellular receptors are present only in the target cells
B. all of the other cells quickly destroy the signal molecules.
C. the target cells have cell membrane bound receptors specific to the signal molecule.
D. only the target cells have the appropriate DNA sequence that must be activated.
, E. cells, which are the target, transport the signal molecule directly to the nucleus. -
ANSWER-C. the target cells have cell membrane bound receptors specific to the signal
molecule.
Which of the following is true of a target cell?
A. It must use G-proteins
B. It must use a tyrosine-kinase pathway
C. It must use c-AMP
D. It must have a second messenger
E. It must have a receptor for the chemical signal - ANSWER-E. It must have a receptor
for the chemical signal
Transduction - ANSWER-the action or process of converting something (especially
energy or a message) into another form
Describe the G-Protein transduction pathway. - ANSWER-A G-protein receptor binds to
the signaling molecule, becoming activated. The G-protein binds to the activated
receptor, adding GTP. The GTP activates the G-protein and will bind to the enzyme,
activating it. The signal molecule is then kicked off, creating a cellular response.
In what sensory system are G-proteins found? - ANSWER-olfactory
When receptors are bound to the plasma membrane, what does this tell us about the
properties of the signal molecules? - ANSWER-Since the receptors are embedded in
the plasma membrane, then the signal molecules for those receptors are not permeable
to the membrane and need help to pass through the membrane.
When receptors are located in the cytoplasm, what does this tell us about the properties
of these signals? - ANSWER-These signals are obviously membrane permeable. Most
cytoplasmic signals are steroids. Since steroids are lipids, then they are permeable to
the membrane.
Which of these extracellular signal molecules could diffuse through a plasma membrane
and bind to an intracellular receptor?
A. glucose
B. estrogen
C. glycerol
D. cellulose
E. starch - ANSWER-B. estrogen
A(n) _____ is an example of a signal molecule that can bind to an intracellular receptor
and thereby cause a gene to be turned on or off.
A. steroid
AND ANSWERS (GRADED A+)
What are the three types of cell signaling? - ANSWER-1. Direct Contact
2. Local
3. Distant
Describe direct contact cell signaling and some examples. - ANSWER-One cell actually
physically touches another
i.e. Gap Junctions (diffusion of signals through a plasma membrane), Plasmodesmata
(diffusion of signals through a plasma membrane), and Cell-Cell Recognition (one cell
have a type of signal molecule while the other cell has a receptor, and they bind and
create a response)
Describe local cell signaling and some examples. - ANSWER-Cells are signaling and
the signal is released into the extracellular liquid; affects cells in the area
i.e. Paracrine (one cell is releasing signal molecules, diffusing into the area, affecting
the cells nearby, for example, a wound) and Synaptic (space between neurons where
neurotransmitters diffuse across the synapsis)
Describe distant cell signaling and some examples. - ANSWER-Signals cells in another
part of the body
i.e. Endocrine System (hormones are sent all over the body to initiate a response)
A compound that is secreted in one part of the body and travels through the
bloodstream to another part of the body where it has an effect is called a(n)
A. Receptor protein
B. Hormone
C. Transmitter
D. Activator - ANSWER-B. Hormone
When a platelet contacts a damaged blood vessel, it is stimulated to release
thromboxane A2. Thromboxane A2 in turn stimulates a vascular spasm and attracts
additional platelets to the injured site. In this example, thromboxane A2 is acting as
____________.
A. direct contact signal molecule
B. local signal molecule
C. distant signal molecule - ANSWER-B. local signal molecule
,What are the three steps of cell signaling? - ANSWER-1. Reception
2. Transduction
3. Response
Where are receptors located? - ANSWER-plasma membrane and cytoplasm
Most receptors are _____________ attached to the plasma membrane. - ANSWER-
proteins
Since receptors are proteins, what does that tell us about the specificity of the
receptors? - ANSWER-Since receptors are proteins, then they are highly specific and
will only bind to a specific signal molecule.
Which molecules determine the tissue specificity of hormones?
A. Receptors.
B. Hormone-response elements.
C. Second messengers.
D. Agonists. - ANSWER-A. Receptors.
Assuming there are a 100 different signaling molecules in your body. What is the
minimum number of receptors that your body needs to make?
A. 1
B. 10
C. 100
D. 1000
E. 1000000 - ANSWER-C. 100
The signal molecule Leptin is 16000 Da protein. Where would you expect to find the
receptors of this molecule?
A. cytoplasm
B. cell membrane
C. I don't know - ANSWER-B. cell membrane
Protein signal molecules are not permeable to the cell membrane but can affect their
target cells because
A. intracellular receptors are present only in the target cells
B. all of the other cells quickly destroy the signal molecules.
C. the target cells have cell membrane bound receptors specific to the signal molecule.
D. only the target cells have the appropriate DNA sequence that must be activated.
, E. cells, which are the target, transport the signal molecule directly to the nucleus. -
ANSWER-C. the target cells have cell membrane bound receptors specific to the signal
molecule.
Which of the following is true of a target cell?
A. It must use G-proteins
B. It must use a tyrosine-kinase pathway
C. It must use c-AMP
D. It must have a second messenger
E. It must have a receptor for the chemical signal - ANSWER-E. It must have a receptor
for the chemical signal
Transduction - ANSWER-the action or process of converting something (especially
energy or a message) into another form
Describe the G-Protein transduction pathway. - ANSWER-A G-protein receptor binds to
the signaling molecule, becoming activated. The G-protein binds to the activated
receptor, adding GTP. The GTP activates the G-protein and will bind to the enzyme,
activating it. The signal molecule is then kicked off, creating a cellular response.
In what sensory system are G-proteins found? - ANSWER-olfactory
When receptors are bound to the plasma membrane, what does this tell us about the
properties of the signal molecules? - ANSWER-Since the receptors are embedded in
the plasma membrane, then the signal molecules for those receptors are not permeable
to the membrane and need help to pass through the membrane.
When receptors are located in the cytoplasm, what does this tell us about the properties
of these signals? - ANSWER-These signals are obviously membrane permeable. Most
cytoplasmic signals are steroids. Since steroids are lipids, then they are permeable to
the membrane.
Which of these extracellular signal molecules could diffuse through a plasma membrane
and bind to an intracellular receptor?
A. glucose
B. estrogen
C. glycerol
D. cellulose
E. starch - ANSWER-B. estrogen
A(n) _____ is an example of a signal molecule that can bind to an intracellular receptor
and thereby cause a gene to be turned on or off.
A. steroid
