cell communication practice test

AP Biology Cell to Cell Communication

Name ____________________________________

Multiple Choice  Identify the the choice that best completes completes the statement statement or answers the the question.

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1. The ______ are a class class of enzymes enzymes that that attach phosphate groups to proteins proteins and play a major major role in the regulation of the cell cycle. a. DNA polymerases  b. growth factors factors c. ICE-like proteases d. protein kinases 2. Cell differentiation differentiation ________. ________. a. occurs in all complex multicelled organisms  b. requires unique unique genes genes in different different cells c. involves selective gene expression d. both a and c e. all of the above 3. The expression expression of a given gene depends on the ________. ________. a. type of cell and its functions  b. chemical chemical conditions conditions c. environmental signals d. all of the above 4. An operon most most typically governs ________. ________. a. bacterial genes  b. a eukaryotic eukaryotic gene c. genes of all types d. DNA replication 5. Eukaryotic genes guide guide ________. a. fast short-term short-ter m activities  b. overall growth growth c. development d. all of the above 6. Hormones may may _____ gene gene transcription transcription in target target cells. cells. a. promote  b. inhibit c. participate in d. both a and b 7. Apoptosis is ________. a. cell division after severe tissue damage  b. programmed programmed cell death death by suicide suicide c. a popping sound in mutated toes 8. Paracrine signaling a. involves secreting cells acting on nearby target cells b y discharging a local  b. c. d. e.

regulator into the extracellular fluid. requires nerve cells to release a neurotransmitter into the synapse. occurs only in paracrine yeast cells. has been found in plants but not animals. involves mating factors attaching to target cells and causing production of new  paracrine cells. 1

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9. What would be true for the signaling system s ystem in an animal cell that lacks the ability to produce GTP? a. It would not be able to activate ac tivate and inactivate the G protein on the cytoplasmic

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side of the plasma membrane.  b. It could activate only the epinephrine system. s ystem. c. It would be able to carry out reception and transduction, but would not be able to respond to a signal. d. Only A and C are true. e. A, B, and C are true. The receptors for a group of signaling molecules kn own as growth factors are often a. ligand-gated ion channels.  b. G-protein-linked receptors. c. cyclic AMP. d. receptor tyrosine kinases. e. neurotransmitters. Sutherland discovered that epinephrine a. signals bypass the plasma membrane of cells.  b. lowers blood glucose by binding to liver cells. c. interacts with insulin inside muscle cells. d. interacts directly with glycogen phosphorylase. e. elevates the cytosolic concentration of cyclic AMP. The general name for an enzyme that transfers phosphate groups from ATP to a protein is a.  phosphorylase.  b.  phosphatase. c.  protein kinase. d. ATPase. e.  protease. Which of the following describes cell communication systems? a. Cell signaling evolved more recently than systems s ystems such as the immune system of vertebrates.  b. Communicating cells are usually close together. c. Most signal receptors are bound to the outer membrane of the nuclear envelope. d. Lipid phosphorylation is a major mechanism of signal transduction. e. In response to a signal, the cell may ma y alter activities by changes in cytosol activity or in transcription of RNA. The toxin of Vibrio cholerae causes profuse diarrhea because it a. modifies a G protein involved in regulating salt and water secretion.  b. decreases the cytosolic concentration of calcium ions, making the cells hypotonic to the intestinal cells. c.  binds with adenylyl cyclase and triggers the formation of cAMP. d. signals inositol trisphosphate to become a second messenger for the release of calcium. e. modifies calmodulin and activates a cascade of p rotein kinases. Which of the following most likely would be an immediate result of growth factor binding to its receptor? a.  protein kinase activity  b. adenylyl cyclase activity c. GTPase activity d.  protein phosphatase activity e.  phosphorylase activity 2

 ____ 16. An inhibitor of phosphodiesterase activity would have which of the following effects? a.  block the response of epinephrine  b. decrease the amount of cAMP in the cytoplasm c.  block the activation of G proteins in response to epinephrine binding to its receptor d.  prolong the effect of epinephrine by maintaining elevated cAMP levels in the

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cytoplasm e.  block the activation of protein kinase A Adenylyl cyclase has the opposite effect of which of the following? a.  protein kinase  b.  protein phosphatase c.  phosphodiesterase d.  phosphorylase e. GTPase If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to a. design a compound that mimics epinephrine and can bind to the epinephrine receptor.  b. design a compound that stimulates cAMP production in liver cells. c. design a compound to stimulate G protein activit y in liver cells. d. design a compound that increases phosphodiesterase activity. e. All of the above are possible approaches. Which of the following statements is true? a. When signal molecules first bind to receptor tyrosine kinases, the receptors  phosphorylate a number of nearby molecules.  b. In response to some G-protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP3 and calcium. c. In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus. d. Toxins such as those that cause botulism and ch olera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule. e. Protein kinase A activation is one possible result of signal molecules binding to G  protein-linked receptors. Which of the substances below is a protein that can hold several other relay proteins as it binds to an activated membrane receptor? a. active transcription factor  b. third messenger c. ligand d. scaffolding protein e.  protein kinase Phosphorylation cascades involving a series of protein kinases are useful fo r cellular signal transduction because a. they are species specific.  b. they always lead to the same cellular response. c. they amplify the original signal manyfold. d. they counter the harmful effects of phosphatases. e. the number of molecules used is small and fixed.

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 ____ 22. Binding of a signaling molecule to which t ype of receptor leads directly to a change in distribution

of ions on opposite sides of the membrane? a. receptor tyrosine kinase  b. G protein-coupled receptor c.  phosphorylated receptor tyrosine kinase dimer d. ligand-gated ion channel e. intracellular receptor  ____ 23. The activation of receptor tyrosine kinases is characterized by a. dimerization and phosphorylation.  b.  binding. c. a phosphorylation cascade. d. GTP hydrolysis. e. channel protein shape change.  ____ 24. Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect onl y

target cells because a. only target cells retain the appropriate DNA segments.  b. intracellular receptors are present only in target cells. c. most cells lack the Y chromosome required. d. only target cells possess the cytosolic enzymes that transduce the testosterone. e. only in target cells is testosterone able to initiate the phosphor ylation cascade leading to activated transcription factor.  ____ 25. Consider this pathway: epinephrine  G protein-coupled receptor  G protein  adenylyl cyclase

 cAMP. Identify the second messenger. cAMP G protein GTP adenylyl cyclase G protein-coupled receptor

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a.  b. c. d. e.

Short Answer

26. Any gene or group of of genes together together with its promoter promoter and operator operator sequence is a(n) ________. a.  b. c. d.

repressor operator promoter operon

27. The operon model explains explains the regulation of ________ in prokaryotes. prokaryotes. a.  b. c. d.

replication transcription induction Lyonization

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