front 1 Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because: (A) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor. (B) only target cells retain the appropriate DNA segments. (C) intracellular receptors are present only in target cells. (D) most cells lack the Y chromosome required. (E)only target cells possess the cytosolic enzymes that transduce the testosterone. | back 1 C |
front 2 Which of the following is a correct association? (A) adenylyl cyclase activity and the conversion of cAMP to AMP (B) kinase activity and the addition of a tyrosine (C) phosphorylase activity and the catabolism of glucose (D) GTPase activity and hydrolysis of GTP to GDP (E) phosphodiesterase activity and the removal of phosphate groups | back 2 D |
front 3 Which is NOT a basic method of cell-to-cell communication? (A) mechanical signals (B) diffused chemical signals (C) nerve and blood-transported signals (D) cytoplasmic transfer of signals (E) contact-dependent signals | back 3 A |
front 4 The termination phase of cell signaling requires which of the following? (A) activation of a different set of relay molecules (B) reversing the binding of signal molecule to the receptor (C) converting ATP to camp (D) removal of the receptor (E) apoptosis | back 4 B |
front 5 Choose a common response used to propagate a signal within a cell. (A) Dephosphorylation of a target (B) triggering of a second messenger (C) enzyme cleavage | back 5 B |
front 6 The variation in responses from different cells to the same ligand is due to differences in ________. (A) signal amplification (B) protein expression (C) receptor types | back 6 B |
front 7 The general name for an enzyme that transfers phosphate groups from ATP to a protein is: (A) protease (B) phosphate (C) phosphorylase (D) protein kinase | back 7 D |
front 8 Chemical signal pathways: (A). are absent in bacteria, but are plentiful in yeast. (B) involve the release of hormones into the blood. (C). often involve the binding of signal molecules to a protein on the surface of a target cell. (D). operate in animals, but not in plants | back 8 D |
front 9 Adenylyl cyclase has the opposite effect of which of the following? (A). phosphodiesterase (B). protein phosphatase (C). GTPase (D). protein kinase (E). phosphorylase | back 9 A |
front 10 Which of the following proteins is directly activated by a G
protein? (B). protein kinase G (C). adenylate cyclase (D). Tyrone kinase (E). calmodulin | back 10 C |
front 11 Which of the following enzymes catalyzes synthesis of diacylglycerol
and inositol triphosphate? (B). phenylethanolamine N-methyl transferase (C) phospholipase C (D). phosphoprotein phosphatase (E). cyclooxygenase | back 11 C |
front 12 What chemical messenger diffuses to neighboring cells to exert an
effect? (B). paracine (C). hormone (D). neurotransmitter (E). neurohormone | back 12 B |
front 13 Which of the following is true of the mating signal transduction pathway in yeast? (A). The signal reception, transduction, and response occur in the nucleus. (B). Mating type a secretes a signal called a factor. (C). Scientists think the pathway evolved long after multicellular creatures appeared on Earth. (D). The pathway carries an electrical signal between mating cell types.\ (E). The molecular details of the pathway in yeast and in animals are very different. | back 13 B |
front 14 Which of the following most likely would be an immediate result of
growth factor binding to its receptor? (B). phosphorylase activity (C). protein kinase activity (D). adenylyl cyclase activity (E). GTPase activity | back 14 C |
front 15 Second messenger molecules directly: (A). increase intracellular calcium contrition (B). change regulation of gene activity (C). change enzyme activity (D). all of the answers are correct (E). change the regulation of ion channels | back 15 D |
front 16 ____ are one the of small hydrophobic ligands used in cellular signaling. (A). large ions (B) steroid hormones (C). peptides | back 16 B |
front 17 Peptides are one type of ________ used in cellular signaling. (A). hydrophilic ions (B). water-soluble ligands (C). small hydrophobic ligands | back 17 B |
front 18 Which of the following enzymes catalyzes synthesis of cAMP? (A). adenylate cyclase (B). tyrosine β-hydroxylase (C). phospholipase A2 (D). phosphodiesterase (E). tyrosine kinase | back 18 A |
front 19 Which of the following is the most common second messenger in the human body? (A). cGMP (B). calcium (C). IP3 (D). DAG (E). cAMP | back 19 E |
front 20 What molecule, whose synthesis is catalyzed by phospholipase C,
triggers the release of calcium from the endoplasmic
reticulum? (B). inositol biphosphate (C). cGMP (D). inositol triphosphate (E). phosphatidylinositol biphosphate | back 20 D |
front 21 Paracrine signaling (B). occurs only in paracrine yeast cells. (C). involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid. (D). requires nerve cells to release a neurotransmitter into the synapse. (E). involves mating factors attaching to target cells and causing production of new paracrine cells. | back 21 C |
front 22 ________ secrete mating factors in preparation for sharing genetic material with another of their species. (A). yeast (B). bacteria (C). fungi | back 22 A |
front 23 The activation of receptor tyrosine kinases is characterized by:
(B). dimerization and phosphorylation. (C). GTP hydrolysis (D). channel protein change shape (E). IP3 binding. | back 23 B |
front 24 The phosphorylation of a target is used to ________ a signal within a cell. (A). initiate (B). respond to (C). propagate | back 24 C |
front 25 Cells use protein molecules called receptors to receive signals, and the two types of receptors are ________ and cell-surface receptors. (A). internal (B). external (C). gap junction | back 25 A |
front 26 After a ligand binds to a cell-surface receptor, a series of ________ steps occurs that integrates the events eventually leading to a change in the cellular environment. (A). signaling stream (B). signaling cascade (C). enzymatic cascade B | back 26 B |
front 27 The binding of lipophilic messengers, such as steroid hormones, to
their receptors triggers (B). adenylyl cyclase activation (C). cyclic nucleotide formation (D). gene transcription (E). G protein inhibition | back 27 D |
front 28 Signal transduction pathways that influence gene expression do so by ________. (A). regulating RNA transcription (B). degrading proteins (C). influencing DNA copy number | back 28 A |
front 29 In ________ signaling, a cell targets itself. (A). paracrine (B). autocrine (C). endocrine | back 29 B |
front 30 ________ are small molecules that diffuse between cells directly connected by gap junctions. (A). intracellular mediators (B). nerve impulses (C). synaptic signals | back 30 A |
front 31 T-cells that incorrectly respond to “self proteins” are targeted for ________ to prevent damage to the organism. (A). necrosis (B). reprogramming (C). apoptosis | back 31 C |
front 32 When adenylyl cyclase is activated, (B). cAMP is formed (C). protein kinases are metabolized. (D). steroids are produced (E). cAMP is broken down | back 32 B |
front 33 Cyclic AMP activates (A). protein kinase A (B). a G protein (C). hormone receptors (D). protein hormones (E). adenylyl cyclase | back 33 A |
front 34 In the yeast signal transduction pathway, after both types of mating
cells have released the mating factors and the factors have bound to
specific receptors on the correct cells, (B). the cell membranes fall apart, releasing the mating factors that lead to new yeast cells. (C). one cell nucleus binds the mating factors and produces a new nucleus in the opposite cell. (D). a growth factor is secreted that stimulates mitosis in both cells. (E). the cells then produce the a factor and the α factor. | back 34 A |