BS 161 EXAM 3 NEWEST EXAM COMPLETE 200
QUESTIONS AND CORRECT DETAILED ANSWERS
(VERIFIED ANSWERS) |ALREADY GRADED A+
Nicotine from cigarette smoke acts as a ligand and associates with specific cells in the
nervous system. Nicotine eventually produces feelings of pleasure and well-being.
Below are the events that happen in the cellular response to nicotine. Place the events
in the correct order to describe the steps in the signaling pathway.
- ans --1) Nicotine enters the body and binds to an acetylcholine receptor.
2) Nicotine binding to the acetylcholine receptor opens an ion channel.
3) An influx of ions into the neurons causes a signal to be sent to 'reward' areas of the
brain.
4) The signal causes dopamine release in the brain, which causes good feelings
5) Nicotine is quickly eliminated from the body, which causes nicotine cravings.
Which of the following types of cellular activities can be a response to cell signaling?
- ans --Cell signals are released to communicate with other cells.
Cell division is triggered.
Enzymes activities are changed.
Gene expression patterns are changed.
Of the choices below, what is the most likely reason why paracrine signaling does not
activate the cell producing the signaling molecule? - ans --The cell does not have the
proper receptor
Estrogen and testosterone are small, hydrophobic signaling molecules. They:
- ans --can cross the plasma membrane by simple diffusion.
You strip off all proteins on the cell surface using a protease (an enzyme that destroys
proteins). Now, when you add a specific signaling molecule, the cell still responds. Why
is this? - ans --The receptor is in the interior of the cell
The cellular response to a signal depends on the:
- ans --binding affinity of the receptor to the signaling molecule.
concentration of the signaling molecule in the vicinity of the receptor.
level of expression of the signal transduction proteins.
level of expression of proteins that terminate the response.
Proteins that can phosphorylate a substrate are called: - ans --kinases
A protein on a cell surface that binds to a signaling molecule is an example of which of
the following elements of cellular communication? - ans --a receptor protein
,In communication between cells, the _____ produces the signaling molecule, also
known as the _____; the _____ produces the _____, to which the signaling molecule
binds. (Put the terms in the correct order.)
- ans --1) signaling cell
2) ligand
3) responding cell
4) receptor
Communication between cells via Sonic Hedgehog during spinal cord development is
an example of: - ans --paracrine signaling
In the Fight or Flight Signaling pathway, glycogen synthase is phosphorylated in
response to adrenaline binding to the receptor. Based on the handout, does this
activate or inactivate this enzyme? - ans --inactivate
How does an "activated" receptor transfer information into the cell? - ans --through a
conformational change of the receptor
(Select all correct responses) In the fight-or-flight response, which of the following
proteins are activated by ligand binding?
- ans --the receptor
protein kinase A
Protein kinase A (PKA) is a signal transduction protein that causes cells to generate
glucose in response to adrenaline. If a mutation disrupted PKA function, what would
happen to the amount of glucose generated in response to a fixed amount of
adrenaline? - ans --it would decrease
In the Fight or Flight signaling pathway, glycogen synthase is inhibited in response to
adrenaline, why? - ans --Because cells need to release sugar in times of crisis.
In the Fight or Flight pathway handout, how many proteins are activated by
phosphorylation? - ans --2
What is the general role of GTP binding in signal transduction?
- ans --GTP changes the shape of G proteins, allowing new interactions to occur
(Select all correct responses) Based on the figure, which type of bond/interaction are
involved in the binding of cAMP to PKA? - ans --hydrogen
ionic
Glycogen is a branched polymer found in animal cells. A monomer of glycogen is circled
in the image. What types of monomers are the building blocks of glycogen? - ans --
glucose
, The image below shows how a protein is altered by phosphorylation. Why does
phosphorylation typically alter the structure of proteins? - ans --Because a polar
functional group is converted to a negatively charged functional group, new ionic
interactions can occur
Termination is an important step in adrenaline signaling because it:
- ans --allows organisms to respond to new stresses.
prevents an excessive response to adrenaline.
allows an appropriate level of response.
In the G protein-coupled signal transduction pathway involved in the fight or flight
response, phosphatases are responsible for the inactivation of: (Hint: This was not
directly discussed, you will need to apply your understanding of cell signaling to answer
the question.) - ans --the protein target activated by kinase A
How are steroid hormone receptors and cell-surface receptors similar? (You'll need to
think carefully about this question) - ans --Both types undergo a conformational change
when they bind to their ligand.
Phosphatases are a family of enzymes that remove phosphate groups from specific
proteins; these phosphate groups had been added to the proteins by protein kinases.
Vanadate is an inhibitor of phosphatases in eukaryotic cells. What effect would
vanadate have on the response of cells to signals received by receptor kinases?
- ans --The response of the cell would last longer than it normally would.
Signal amplification relies on: - ans --a sequential increase in the different components
of the signal transduction pathway.
The extent and duration of a cellular response to a signal depend on the:
- ans --binding affinity of the receptor to the signaling molecule.
level of expression of the signal transduction proteins.
concentration of the signaling molecule in the vicinity of the receptor
level of expression of proteins that terminate the response.
The image above shows a ligand binding to a receptor. Which of the following
molecules is more likely to represent this ligand and why? - ans --Molecule B, since it
contains mostly polar covalent bonds and will not be able to cross the plasma
membrane.
The activation of protein kinase A by cyclic AMP binding likely occurs because of: - ans
--a conformational change to protein kinase A.
What is the function of adenylyl cyclase? - ans --to form cyclic AMP
Suppose you are a research scientist studying the fight or flight response in cultured
liver cells. You inject these cells with cholera toxin. What outcome would you predict?
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