cell communication

After estrogen binds to receptors, these estrogen receptors gain ______ activity. A. GTP binding B. protein kinase C. phospholipase D. transcription factor E. phosphatase

D. transcription factor

A G-protein coupled receptor associates with a G protein that contains how many subunits? A. 0 B. 2 C. 1 D. 4 E. 3

E. 3

When epidermal growth factor binds to its _____________ the receptor phosphorylates itself, triggering a signal transduction pathway. A. enzyme-linked receptor B. G-protein coupled receptor C. thermoreceptor D. ligand-gated ion channel receptor E. mechanoreceptor

A. enzyme-linked receptor

When the concentration of a ligand is equal to the KD which of the following is true? A. half of the receptors are bound to ligands. B. half of the ligands are bound to receptors. C. all of the ligands are bound to receptors. D. all of the receptors are bound to ligands. E. all of the ligands and receptors are bound to each other.

A. half of the receptors are bound to ligands.

In some cases, just a few hormone molecules binding to the surface of a cell can trigger a very large response because ____. A. the signal is amplified by activation of enzymes that each catalyze multiple reactions B. the signal is amplified by activation of transcription factors that each catalyze multiple reactions C. the hormone triggers the cell to release more hormones, amplifying the signal D. each hormone can bind to multiple receptors simultaneously causing amplification of the signal E. each hormone can bind to transcription factors simultaneously causing amplification of the signal

A. the signal is amplified by activation of enzymes that each catalyze multiple reactions

You are testing a new chemotherapy drug that blocks a kinase in the cytoplasm that helps carry signals to the nucleus causing the cell to divide. If you expose cells to the drug at the same time you administer a hormone that should cause the cell to divide, the following steps would be blocked. _____ Receptor activation ____ Signal transduction ____ Activation of transcription factors ____ Cell division

Signal transduction, Activation of transcription factors, Cell division

Apoptosis is used in humans in order to eliminate cells infected by viruses, cells that are worn out, and those that have the potential to cause cancer.

True

Hormones must bind a receptor to elicit a cell response, regardless of whether they operate locally or at long distances.

True

If IP3 binds a Ca2+ ligand-gated ion channel in the endoplasmic reticulum then cytosolic Ca2+ levels will rise in the cell.

True

In terms of cell signaling, estrogen in animal cells works in a similar fashion as the plant hormone auxin via binding to intracellular receptors.

True

Ligands that promote cell death are typically found on the surface of cells of the immune system that recognize abnormal cells and target them for destruction.

True

One common feature with G-protein coupled, enzyme-linked, and growth factor receptors is that their activation leads to activation of protein kinases.

True

When a cell responds to a signal it sent this is an example of _____. A. Autocrine signaling B. Contact-dependent signaling C. Direct intercellular signaling D. Endocrine signalling E. Paracrine signaling

A. Autocrine signaling

The process through which cells can detect and respond to signals in their extracellular environment is _____. A. Cell communication B. Reception C. Sensory response D. Cell sensation E. Transduction

A. Cell communication

Smooth muscle cells in the airways relax while those in the blood vessels contract in response to the hormone epinephrine. What would you expect to be different in these two types of cells exposed to epinephrine? A. Types of proteins expressed. B. Rate of metabolism. C. Exposure to epinephrine released by neighboring cells. D. Activation of protein kinases. E. Presence of epinephrine receptors.

A. Types of proteins expressed.

When epinephrine binds to its G-protein linked receptor ____ is activated producing ___. A. adenylyl cyclase, cAMP B. enzyme linked receptors, protein kinase C. phospholipase C, diacylglyceride D. kinase, calcium E. kinase, transcription factor

A. adenylyl cyclase, cAMP

Some anti-cancer drugs block signal transduction pathways activated by growth factors. Which of the following would be a good target for such a drug? A. An inhibitor of a protein kinase cascade. B. An inhibitor of adenylyl cyclase. C. An inhibitor of Ca2+ release D. An inhibitor of phospholipase C. E. A phosphatase inhibitor.

A. An inhibitor of a protein kinase cascade.

Adenylyl cyclase is to cAMP as ________ is to IP3. A. protein kinase A B. phospholipase C C. protein kinase C D. Raf1 E. calmodulin

B. phospholipase C

What do enzyme-linked receptors and growth factor receptors have in common? A. Both act as transcriptional factors. B. Both possess kinase activity when bound to a hormone. C. Both seldom affect the expression of genes within the nucleus. D. Both regulate specific G proteins when bound to a hormone. E. Both regulate the transport of ions through channels.

B. Both possess kinase activity when bound to a hormone.

What do G-protein coupled, enzyme-linked, and ligand-gated ion channel receptors have in common? A. They bind similar hormones. B. They change their conformation when bound to a hormone. C. They associate with a protein bound to GDP or GTP. D. They are all linked to protein kinase activation. E. They open ion channels.

B. They change their conformation when bound to a hormone.

The production of second messengers in signal transduction offers at least two advantages, speed and A. specificity. B. amplification. C. one-to-one stoichiometry. D. reversibility. E. affinity.

B. amplification.

When a cell secretes a growth factor that binds to receptors on its own membrane preventing it from proliferating this is an example of ____. A. endocrine signaling B. autocrine signaling C. direct intercellular signaling D. contact-dependent signaling E. paracrine signaling

B. autocrine signaling

When cAMP is produced in a cell it will then ______. A. serve as a substrate of protein kinase A B. bind to a repressor of protein kinase A C. increase transcription of protein kinase A D. dephosphorylate proteins phosphorylated by protein kinase A E. inhibit protein kinase A

B. bind to a repressor of protein kinase A

When sodium ions move from one cardiac muscle cell to an adjacent cell causing them to contract in unison this is an example of ____. A. autocrine signaling B. direct intercellular signaling C. endocrine signaling D. paracrine signaling E. contact-dependent signaling

B. direct intercellular signaling

Diabetics can be given the ____ insulin which binds to receptors on cells throughout the body increasing glucose uptake. A. transcription factor B. hormone C. G-protein D. kinase E. response element

B. hormone

When a cell secretes a growth factor that binds to receptors on neighboring cells causing them to proliferate this is an example of ____. A. direct intercellular signaling B. paracrine signaling C. endocrine signaling D. contact-dependent signaling E. autocrine signaling

B. paracrine signaling

When insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake this is an example of ____. A. autocrine signaling B. paracrine signaling C. endocrine signaling D. contact-dependent signaling E. direct intercellular signaling

C. endocrine signaling

When a neurotransmitter released from one neuron binds to a ______ on a second neuron, that neuron depolarizes and fires. A. voltage-gated ion channel B. G-protein coupled receptor C. ligand-gated ion channel D. enzyme-linked receptor E. nuclear receptor

C. ligand-gated ion channel

During exposure to elevated glucose, a yeast cell will increase its uptake of glucose. Describe the mechanism by which the yeast sense the extracellular glucose. A. By the increase in energy outside the cell when the glucose is metabolized. B. By glucose uptake through glucose transporters. C. By glucose binding to glucose receptors. D. By glucose diffusing into the nucleus and binding to transcription factors. E. By the increase in energy inside the cell when the glucose is metabolized.

C. By glucose binding to glucose receptors.

What do synaptic signaling and paracrine signaling have in common? A. Cells release a signal through gap junctions to affect neighboring cells. B. Cells bind a membrane bound signal on a neighboring cell. C. Cells release a signal that affects neighboring cells. D. Cells release a signal that affects cells at long distances. E. Cells release a signal that affects it and neighboring cells.

C. Cells release a signal that affects neighboring cells.

Estrogen is a lipid soluble hormone that can easily cross membranes. Knowing this, what can be concluded about estrogen receptors? A. The receptors would be on the plasma membrane. B. The receptors would also be lipid soluble and able to cross membranes. C. The receptors would be found inside the cell. D. The receptors would be linked to enzymes that triggered a kinase cascade. E. The receptors would be coupled to a G-protein.

C. The receptors would be found inside the cell.

If you add the plant hormone auxin to one side of a plant the cells exposed to the auxin elongate. If you measured auxin levels in plant cells exposed to light what you would you expect to find? A. They would be higher, causing the plant to bend away from the light. B. They would be higher, causing the plant to bend towards the light. C. They would be lower, causing the plant to bend towards the light. D. They would be lower, causing the plant to bend away from the light.

C. They would be lower, causing the plant to bend towards the light.

If the concentration of a ligand is 100 times greater than the Kd of its receptor, _______ of the receptors will be bound to a ligand. A. none B. half C. most D. few

C. most

After being fed glucose a cell increases its intracellular glucose concentrations by _____ . A. decreasing glucose breakdown in the cell B. decreasing glucose receptors on the cell C. increasing membrane glucose receptors D. increasing membrane glucose transporters E. increasing glucose synthesis in the cell

D. increasing membrane glucose transporters

When receptors coupled to phospholipase C are activated, calcium levels in the cytosol increase when ______ A. IP3 binds to ligand-gated channels on the plasma membrane, releasing calcium. B. diacylglycerol binds to ligand-gated channels on the endoplasmic reticulum, releasing calcium. C. phospholipase C phosphorylates the receptor leading to calcium production. D. IP3 binds to ligand-gated channels on the endoplasmic reticulum, releasing calcium. E. diacylglycerol binds to ligand-gated channels on the plasma membrane, releasing calcium.

D. IP3 binds to ligand-gated channels on the endoplasmic reticulum, releasing calcium.

Epinephrine blocks the contraction of muscles in the airways. Which of the other activities of epinephrine is most likely to be regulated by the same type of pathway? A. Increased sweating. B. Stimulation of heart muscle cell contraction. C. Contraction of smooth muscle cells in blood vessels. D. Inhibition of saliva production in salivary glands E. Promotes the breakdown of glycogen in skeletal muscle cells

D. Inhibition of saliva production in salivary glands

When insulin binds to it's G-protein coupled receptor (GPCR) what happens next? A. The G protein loses GDP and gains GTP becoming inactivated. B. The G protein loses GTP and gains GDP becoming activated. C. The G protein loses GTP and gains GDP becoming inactivated. D. The G protein loses GDP and gains GTP becoming activated. E. The insulin enters the cell through the GPCR and diffuses to the nucleus where it interacts with transcription factors.

D. The G protein loses GDP and gains GTP becoming activated.

Following its initial activation, how does a G protein become inactivated? A. The G-protein a subunit containing a GTP eventually reassociates with the G-protein bg dimer. B. It spontaneously loses activity within a few seconds. C. The receptor becomes internalized. D. The G-protein a subunit GTP is hydrolyzed to GDP allowing reassociation of the G-protein a subunit and bg dimer. E. The G-protein a subunit is digested and recycled.

D. The G-protein a subunit GTP is hydrolyzed to GDP allowing reassociation of the G-protein a subunit and bg dimer.

Patients who have type 2 diabetes no longer respond normally to insulin. This symptom would be best explained by A. The nucleus of their cells are altered so that insulin can not bind. B. Type 2 diabetics do not produce insulin. C. The signal transduction pathways in the cells no longer exist. D. Their cells express less insulin receptor. E. The insulin receptors on their cells have mutated.

D. Their cells express less insulin receptor.

Patients who have type 2 diabetes no longer express genes when exposed to insulin. How might this phenomenon be explained? A. The nucleus of their cells are altered so that insulin can not bind. B. The insulin signal transduction pathway becomes permanently activated. C. Insulin can no longer bind to the insulin receptor because the receptor is mutated. D. Transcription factors normally activated by insulin remain off. E. The signal transduction pathways in the cells no longer exist.

D. Transcription factors normally activated by insulin remain off.

A phosphatase is capable of dephosphorylating molecules. What would this enzyme do in a signal transduction pathway that used a kinase cascade? A. Activate the cascade. B. Phosphorylate a transcription factor. C. Serve as a ligand for the receptor. D. Turn off the cascade. E. Phosphorylate a receptor.

D. Turn off the cascade.

Programmed cell death is known as ____. A. autophagy B. mitosis C. cell genesis D. apoptosis E. meiosis

D. apoptosis

A key is placed into a keyhole then turned and the door opens. When considering the components of cell signaling, the action of turning the key would best correspond to A. the cell response that occurs when the receptor binds the hormone B. signal transduction that occurs when the receptor binds the hormone C. the binding site of the receptor D. conformational change in the receptor once bound to the hormone E. the concentration of the hormone

D. conformational change in the receptor once bound to the hormone

Hormones are released from one cells and act on other cells in distant organs and are thus an example of ____. A. autocrine signaling B. contact-to-contact signaling C. paracrine signaling D. endocrine signaling E. intercellular signaling

D. endocrine signaling

The molecule directly responsible for breaking down cAMP to inactive AMP is A. protein kinase A B. adenylyl cyclase C. protein phosphatase D. phosphodiesterase E. GTPase

D. phosphodiesterase

A hormone binds a receptor and activates the cAMP signal transduction pathway ultimately leading to the cell response. If you wanted to develop a drug to block this pathway the drug would need to inhibit _____ A. protein phosphatases remove phosphates from proteins initially activated by protein kinase A. B. GTP on the alpha subunit of the G protein being hydrolyzed to GDP. C. hormone release from the receptor. D. phosphodiesterase. E. adenylyl cyclase.

E. adenylyl cyclase.

Phospholipase C hydrolyzes a membrane phospholipid to produce ____ A. IP3 only. B. protein kinase C only. C. diacylglycerol only. D. both IP3 and protein kinase C. E. both IP3 and diacylglycerol.

E. both IP3 and diacylglycerol.

IP3 binds to _____ receptors. A. enzyme-linked B. G-protein coupled C. phospholipase type-I D. sensor kinase E. ligand-gated Ca2+ channel

E. ligand-gated Ca2+ channel

A substrate binding to an enzyme is most similar to a signal molecule binding to a A. transcriptional factor. B. kinase. C. second messenger. D. G-protein. E. receptor.

E. receptor.

Apoptosis through the extrinsic pathway is activated by factors such as lack of oxygen or growth factors.

False

Auxin is a plant hormone that causes cells to shorten and allow plant growing tips to move toward the sun.

False

Cyclic AMP activates protein kinase C in producing a cell response.

False

G proteins and Ras are activated when bound to GDP.

False

If epinephrine increases glycogen metabolism in muscle cells it would have the same function in brain cells.

False