Download Cell Communication Problem Set

Cell Communication Problem Set:
AP Biology
Problem 1: Receptors
A protein receptor binds a hormone outside the cell membrane and activates a protein kinase
inside the cell. Is the receptor a peripheral or integral membrane protein?
A.
B.
Membrane receptors are peripheral, or associated with the surface of the bilayer.
Association with a hormone results in the release of a lipid signal that activates protein
kinases.
Membrane receptors associated with signaling are all integral membrane proteins that can
transmit signals through the lipid bilayer.
Problem 2: Signal Responses I
Signaling between cells usually results in the activation of protein _______.
A.
B.
C.
D.
lipases
kinases
proteases
nucleases
Problem 3: Signal Responses II
Which of the following is NOT a typical event associated with cell signaling?
A.
B.
C.
D.
E.
Activation of G-proteins by exchanging GTP for GDP
Production of the second messengers cAMP and IP3
Activation of protein kinases
Release of calcium ions from cell membranes
Stimulation of apoptosis
Problem 5: Bacterial Cell Signaling
E.coli respond to increased solute concentrations by phosphorylation of the membrane receptor
_______________, which transfers a phosphate to the subcellular second messenger
______________ that initiates transcription of the ___________ gene producing a protein that
can prevent solute entry and preserve the osmotic integrity of the cell.
A.
B.
C.
EnvZ, OmpR, OmpF
OmpR, EnvZ, OmpF
OmpF, OmpR, EnvZ
D.
E.
OmpR, OmpF, EnvZ
OmpF, EnvZ, OmpR
Problem 6: Steroid Hormones
Estrogen and testosterone are steroid hormones, and are most likely to bind to:
A.
B.
C.
D.
membrane ion channel
enzyme linked membrane receptor
G-protein linked membrane receptor
cytoplasmic receptors
Problem 7: Second Messengers
Sending a signal through the cell membrane can lead to the production of second messengers
inside the cell. Which of the following can serve as second messengers?
A.
B.
C.
D.
E.
cAMP
Ca++
IP3
NO (nitric oxide)
all of the above
Problem 8: Protein Kinase Cascades
Some receptors for growth factors activate a protein kinase cascade, with the participation of
multiple enzymes to effect a change in gene expression. Which of the following statements about
a protein kinase cascade are true?
A.
B.
C.
D.
E.
Multiple steps allow the amplification of the signal.
External signals can lead to changes in gene expression.
Multiple steps leading to kinase activations can result in cells having different responses,
depending on the presence or absence of target proteins.
Multiple steps in an activation mean that abnormal stimulation of a cell response such as
growth can occur with mutations in more than one gene.
All of the above are true.
Problem 9: G-proteins
The endogenous GTPase activity of G-proteins serves to:
A.
B.
C.
D.
stimulate the activity of enzymes by producing energy.
synthesize cGMP as a second messenger.
synthesize GTP as an energy source.
hydrolyze GTP returning the G protein to a pre-stimulated level of activity.
Problem 10: Signaling Events
In a fight-or-flight response, epinephrine released by the adrenal glands binds to a membrane
receptor on muscle cells. Which of the following events result from ligand binding?
A.
B.
C.
D.
E.
G-protein is activated by binding GTP and causing adenylyl cyclase to produce cAMP.
The second messenger, cAMP, activates protein kinase A which inhibits glycogen
synthetase blocking glycogen synthesis.
Protein kinase A activates phosphorylase kinase, which transfers a phosphate that activates
glycogen phosphorylase. This leads to the breakdown of glycogen and the production of
glucose-1-phosphate.
Glucose produced from glucose-1-P stimulates glycolysis, producing energy for muscle
contraction.
All of the above.
Problem 11: Gap Junctions
Direct cellular connections such as gap junctions in animal cells and plasmodesmata in plant
cells permit:
A.
B.
C.
D.
E.
adjacent cells to adhere strongly to each other.
second messengers produced in one cell to rapidly diffuse into and stimulate events in
surrounding cells.
adjacent cells to form a water-tight barrier between their membranes.
protein kinases to flow between cells, coordinating cellular responses in a tissue.
the rapid exchange of genetic information between adjacent cells.
Problem 12: Cancer Therapy
A new drug, STI-571 or Gleevec specifically inhibits the Abl tyrosine kinase that is mutated in
chronic myeloid leukemia. Treating patients with the drug dramatically improves survival, but
people with a "blast crisis" form of the cancer begin to develop resistance. Which of the
following statements are important conclusions from studies on the use of STI-571 in cancer
treatment?
A.
B.
Inhibiting signaling pathways can benefit people with cancer.
Rapidly dividing cancer cells that have lost checkpoint systems insuring genome fidelity
C.
D.
can develop resistance to specific anti-cancer drugs.
Acquisition of resistance to STI-571 shows that the same specific enzyme changes occur,
suggesting that developing new drugs that target mutations leading to resistance may
further improve patient survival.
All of the above.