BMB 252 Exam 1 – Study Guide, Practice Questions & Revision Notes
What are the major components of a signaling cascade? - ANS ✔✔1) Extracellular Signal
Molecule
2) Receptor Protein
3) Intracellular Signaling Molecule
4) Effector proteins
Give examples of molecules which can act as signals. - ANS ✔✔•proteins
•small peptides
•amino acids
•nucleotides
•steroids, retinoids
•fatty acids derivatives
•dissolved gases (NO, CO)
What is the difference between signaling molecules, which bind to intracellular and cell-surface
receptors? Give examples of signals that can pass through the plasma membrane. - ANS
✔✔Signals can either bind to cell surface receptors or diffuse through the plasma membrane
and bind inside the cell. Large, hydrophilic molecules bind to cell-surface receptor proteins.
Small, hydrophobic signal molecules, via carrier proteins, travel to the cell and diffuse through
the plasma membrane. (i.e hormones, NO, and CO)
What are the four forms of intercellular signaling? - ANS ✔✔(A) Contact-dependent signaling
requires cells to be in direct membrane-membrane contact.
(B) Paracrine signaling depends on local mediators that are released into the extracellular space
and act on neighboring cells.
,(C) Synaptic signaling is performed by neurons that transmit signals electrically along their axons
and release neurotransmitters at synapses, which are often located far away from the neuronal
cell body.
(D) Endocrine signaling depends on endocrine cells, which secrete hormones into the
bloodstream for distribution throughout the body. Many of the same types of signaling
molecules are used in paracrine, synaptic, and endocrine signaling; the crucial differences lie in
the speed and selectivity with which the signals are delivered to their targets.
What keeps the signal localized in paracrine signaling? - ANS ✔✔•They can be quickly absorbed
by other cells
•Get degraded by extracellular enzymes
•Get trapped in extracellular matrix
What are the differences between synaptic and endocrine signaling (the speed of signal
delivery, concentrations of signal, affinity of receptors and duration of signal)? - ANS ✔✔Signal
delivery in endocrine is slow compared to synaptic. Signal concentration in endocrine is low
compared to synaptic. The affinity of receptors in endocrine is high compared to synaptic's low
affinity. Long duration in endocrine compared to short in synaptic.
What determines the speed of intracellular transmission in response to a signal? - ANS ✔✔It
depends on what pathway the cell takes when activated. Altered protein function is fast while
altered protein synthesis is slow.
What happens to a cell in the absence of signals? - ANS ✔✔apoptosis
What kinds of cellular responses can acetylcholine stimulate? Does it always bind to the same
receptor? - ANS ✔✔It can decrease the rate of firing (heart), secretion of saliva in salivary gland
cells, and can contract in skeletal muscle cells. No, it can bind to different receptors on different
cells.
, Make examples of cellular processes that depend on signaling. - ANS ✔✔Surviving, growth and
division, and differentiation.
Which type of feedback can provide a signal, which would persist for a life-time of an organism?
- ANS ✔✔Postive feedback loop
How can a signal be turned off? - ANS ✔✔•Some signals are enzymatically degraded
•Active removal by transporters (ion pumps); this is typical for many neurotransmitters
•Diffusion, dilution, degradation: typical for hormones
•Short half-life due to interaction with other molecules (NO, CO)
•Shutting different components of signal transduction pathway
What are the different types of mechanisms that can lead to receptor desensitization? - ANS
✔✔1) Receptor Sequestration
2) Receptor Down-regulation
3) Receptor Inactivation
4) Inactivation of signaling protein
5) Production of inhibitory protein
What can be a long term result of a positive and negative feedback loop? Explain. - ANS
✔✔Positive feedback can cause a long term expression of a protein. Negative feedback regulate
the presence of a molecule such as regulating blood glucose levels.
Which of the following binds to an extracellular signal?
(effector Pretein,
receptor,
intracellular signaling molecules,
Both 2 and 3) - ANS ✔✔Receptor
What are the major components of a signaling cascade? - ANS ✔✔1) Extracellular Signal
Molecule
2) Receptor Protein
3) Intracellular Signaling Molecule
4) Effector proteins
Give examples of molecules which can act as signals. - ANS ✔✔•proteins
•small peptides
•amino acids
•nucleotides
•steroids, retinoids
•fatty acids derivatives
•dissolved gases (NO, CO)
What is the difference between signaling molecules, which bind to intracellular and cell-surface
receptors? Give examples of signals that can pass through the plasma membrane. - ANS
✔✔Signals can either bind to cell surface receptors or diffuse through the plasma membrane
and bind inside the cell. Large, hydrophilic molecules bind to cell-surface receptor proteins.
Small, hydrophobic signal molecules, via carrier proteins, travel to the cell and diffuse through
the plasma membrane. (i.e hormones, NO, and CO)
What are the four forms of intercellular signaling? - ANS ✔✔(A) Contact-dependent signaling
requires cells to be in direct membrane-membrane contact.
(B) Paracrine signaling depends on local mediators that are released into the extracellular space
and act on neighboring cells.
,(C) Synaptic signaling is performed by neurons that transmit signals electrically along their axons
and release neurotransmitters at synapses, which are often located far away from the neuronal
cell body.
(D) Endocrine signaling depends on endocrine cells, which secrete hormones into the
bloodstream for distribution throughout the body. Many of the same types of signaling
molecules are used in paracrine, synaptic, and endocrine signaling; the crucial differences lie in
the speed and selectivity with which the signals are delivered to their targets.
What keeps the signal localized in paracrine signaling? - ANS ✔✔•They can be quickly absorbed
by other cells
•Get degraded by extracellular enzymes
•Get trapped in extracellular matrix
What are the differences between synaptic and endocrine signaling (the speed of signal
delivery, concentrations of signal, affinity of receptors and duration of signal)? - ANS ✔✔Signal
delivery in endocrine is slow compared to synaptic. Signal concentration in endocrine is low
compared to synaptic. The affinity of receptors in endocrine is high compared to synaptic's low
affinity. Long duration in endocrine compared to short in synaptic.
What determines the speed of intracellular transmission in response to a signal? - ANS ✔✔It
depends on what pathway the cell takes when activated. Altered protein function is fast while
altered protein synthesis is slow.
What happens to a cell in the absence of signals? - ANS ✔✔apoptosis
What kinds of cellular responses can acetylcholine stimulate? Does it always bind to the same
receptor? - ANS ✔✔It can decrease the rate of firing (heart), secretion of saliva in salivary gland
cells, and can contract in skeletal muscle cells. No, it can bind to different receptors on different
cells.
, Make examples of cellular processes that depend on signaling. - ANS ✔✔Surviving, growth and
division, and differentiation.
Which type of feedback can provide a signal, which would persist for a life-time of an organism?
- ANS ✔✔Postive feedback loop
How can a signal be turned off? - ANS ✔✔•Some signals are enzymatically degraded
•Active removal by transporters (ion pumps); this is typical for many neurotransmitters
•Diffusion, dilution, degradation: typical for hormones
•Short half-life due to interaction with other molecules (NO, CO)
•Shutting different components of signal transduction pathway
What are the different types of mechanisms that can lead to receptor desensitization? - ANS
✔✔1) Receptor Sequestration
2) Receptor Down-regulation
3) Receptor Inactivation
4) Inactivation of signaling protein
5) Production of inhibitory protein
What can be a long term result of a positive and negative feedback loop? Explain. - ANS
✔✔Positive feedback can cause a long term expression of a protein. Negative feedback regulate
the presence of a molecule such as regulating blood glucose levels.
Which of the following binds to an extracellular signal?
(effector Pretein,
receptor,
intracellular signaling molecules,
Both 2 and 3) - ANS ✔✔Receptor
