Deck 9: Cell Communication

Question 1

Which of the following types of molecules is LEAST involved in cell communication?

A) carbohydrates
B) lipids
C) steroids
D) proteins
E) neurotransmitters

Answer 1

carbohydrates

Question 2

A substrate binds an enzyme as a signal molecule binds a

A) second messenger.
B) kinase.
C) receptor.
D) transcriptional factor.
E) G-protein.

Answer 2

receptor.

Question 3

During exposure to elevated glucose, a yeast cell's membrane glucose transporters will rapidly increase so the cell can import glucose. Which would represent the yeast cell response?

A) increased membrane glucose transporters
B) increased membrane glucose receptors
C) increased glucose transport into the cell
D) both increased membrane glucose transporters and glucose receptors
E) both increased membrane glucose transporters and glucose transport into the cell

Answer 3

both increased membrane glucose transporters and glucose transport into the cell

Question 4

During exposure to elevated glucose, a yeast cell's membrane glucose transporters will rapidly increase so the cell can import glucose. Which would represent the signal for the yeast cell?

A) glucose transporters
B) glucose receptors
C) glucose
D) glucose transport into the cell
E) glucose kinase

Question 5

What type of cell communication is said to occur if a cell secretes a growth factor that then acts on neighboring cells to cause them to proliferate?

A) contact-to-contact signaling
B) intercellular signaling
C) autocrine signaling
D) paracrine signaling
E) endocrine signaling

Question 6

What type of signaling occurs when insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake?

A) contact-to-contact signaling
B) intercellular signaling
C) autocrine signaling
D) paracrine signaling
E) endocrine signaling

Question 7

What do we call molecules involved in long-distance signaling?

A) kinases
B) transcription factors
C) hormones
D) response elements
E) receptors

Question 8

Which of the following represents a long-distance signaling mechanism?

A) contact-to-contact signaling
B) intercellular signaling
C) autocrine signaling
D) paracrine signaling
E) endocrine signaling

Question 9

What do synaptic signaling and paracrine signaling have in common?

A) Cells release a signal that affects it and neighboring cells.
B) Cells release a signal that affects cells at long distances.
C) Cells release a signal through gap junctions to affect neighboring cells.
D) Cells bind a membrane bound signal on a neighboring cell.
E) Cells release a signal that affects neighboring cells.

Question 10

Which of the following is not a common way signals are relayed between cells?

A) Contact-dependent signaling
B) Autocrine signaling
C) Direct intercellular signaling
D) Paracrine signaling
E) All of the above are ways signals are relayed between cells

Question 11

The KD or dissociation constant between a receptor and its hormone/ligand is

A) a measure of the binding affinity the receptor has for the hormone.
B) the hormone concentration where half the receptors are bound to hormone.
C) the hormone concentration where all of the receptors are bound to hormone.
D) both a measure of the binding affinity the receptor has for the hormone and the hormone concentration where half the receptors are bound to hormone.
E) both a measure of the binding affinity the receptor has for the hormone and the hormone concentration where all the receptors are bound to hormone.

Question 12

A key is placed into a keyhole then turned and the door opens. Which of the following components of cell signaling would best correspond to turning the key?

A) the hormone
B) the receptor
C) conformational change in the receptor once bound to the hormone
D) signal transduction
E) the cell response

Question 13

A key is placed into a keyhole then turned and the door opens. Which of the following components of cell signaling would best correspond to the keyhole?

A) the hormone
B) the receptor
C) conformational change in the receptor once bound to the hormone
D) signal transduction
E) the cell response

Question 14

Once bound to a hormone, this receptor becomes active and catalyzes the transfer of a phosphate group to itself or intracellular proteins.

A) G-protein coupled receptor
B) enzyme-linked receptor
C) ligand-gated ion channel receptor
D) mechanoreceptor
E) thermoreceptor

Question 15

Which of the following order of events is most accurate for activation of G-protein coupled receptor (GPCR) signaling pathways?

A) Hormone binds GPCR, GPCR binds with G protein, G protein loses GDP and gains GTP, G-protein alpha subunit activates intracellular proteins.
B) Hormone binds GPCR, G protein loses GDP and gains GTP, GPCR binds with G protein, G-protein alpha subunit activates intracellular proteins.
C) Hormone binds GPCR, GPCR binds with G protein, G-protein alpha subunit activates intracellular proteins, G protein loses GDP and gains GTP.
D) Hormone binds GPCR, G protein loses GDP and gains GTP, G-protein alpha subunit activates intracellular proteins, GPCR binds with G protein.
E) GPCR binds with G protein, hormone binds GPCR, G protein loses GDP and gains GTP, G-protein alpha subunit activates intracellular proteins.

Question 16

A G-protein coupled receptor associates with a G protein that contains how many subunits?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 17

Which of the following is TRUE of ligand-gated ion channels?

A) They bind ions with high affinity.
B) They tend to allow any ion to pass through the channel.
C) The intracellular domain of the channel contains the binding site for the ligand.
D) They open upon binding the ligand to allow specific ions to pass through them.
E) Ligand binding closes the channels preventing further ion passage through the channel.

Question 18

Which of the following statements about steroid receptors is FALSE?

A) The receptors undergo a conformational change after binding the steroid.
B) The receptors are localized to the plasma membrane.
C) Once the steroid binds the receptor, the steroid/receptor complexes dimerize.
D)Steroid receptors act as transcriptional factors, regulating the expression of certain genes and the subsequent production of proteins.
E) Steroid receptors are localized to either the cytoplasm or nucleus.

Question 19

Which of the following receptor and signal transduction molecules are mismatched?

A) sensor kinase receptor (NarQ): NarL
B) G-protein coupled receptor: adenylyl cyclase
C) G-protein coupled receptor: phospholipase C
D) enzyme linked receptors: protein kinase
E) steroid receptor: calcium

Question 20

When assembling a fish aquarium one must add a conditioner to the water that contains bacteria capable of metabolizing fish waste such as ammonia, nitrate, and nitrite that accumulates in the aquaria water. Which of the following components of signal reception and transduction is NOT required for the bacterial two-component regulatory system for metabolizing these nitrogenous waste products?

A) NarQ receptor
B) NarL transcriptional activator
C) a protein kinase
D) metabolic enzymes
E) ligand-gated calcium channel

Question 21

Which of the following is capable of dephosphorylating molecules?

A) phospholipase C
B) protein kinase A
C) Grb2/Sos/Ras complex
D) phosphatase
E) IP₃

Question 22

Adenylyl cyclase is to cAMP as ________ is to IP₃.

A) protein kinase A
B) protein kinase C
C) calmodulin
D) Raf1
E) phospholipase C

Question 23

Which of the following is LEAST likely involved in calcium signaling?

A) IP₃
B) calmodulin
C) protein kinase A
D) protein kinase C
E) phospolipase C

Question 24

Estrogen is most likely to exert its effects by regulating

A) protein kinases.
B) phopholipase C.
C) expression of genes and production of specific proteins.
D) cyclic AMP.
E) Ca²⁺.

Question 25

What do enzyme-linked receptors and growth factor receptors have in common?

A) Both possess kinase activity when bound to a hormone.
B) Both regulate specific G proteins when bound to a hormone.
C) Both act as transcriptional factors.
D) Both regulate the transport of ions through channels.
E) Both seldom affect the expression of genes within the nucleus.

Question 26

Which of the following represents the correct sequence of events in the cAMP signal transduction pathway?

A) G protein?cAMP?adenylyl cyclase?protein kinase A?cell response
B) G protein?adenylyl cyclase?protein kinase A?cAMP?cell response
C) G protein?protein kinase A?adenylyl cyclase?cAMP?cell response
D) G protein?adenylyl cyclase?cAMP?protein kinase A?cell response
E) adenylyl cyclase?G protein?cAMP?protein kinase A?cell response

Question 27

A hormone binds a receptor and activates the cAMP signal transduction pathway ultimately leading to the cell response. Which of the following is NOT a likely mechanism for reversing (or shutting off) cAMP transduction?

A) The hormone dissociating from the receptor.
B) The GTP on the alpha subunit of the G protein is hydrolyzed to GDP.
C) Activate phosphodiesterase.
D) Activate adenylyl cyclase.
E) Protein phosphatases remove phosphates from proteins initially activated by protein kinase A.

Question 28

Which molecule is directly responsible for breaking down cAMP to inactive AMP?

A) protein kinase A
B) adenylyl cyclase
C) phosphodiesterase
D) GTPase
E) protein phosphatase

Question 29

The production of second messengers in signal transduction offers at least two advantages, speed and

A) specificity.
B) amplification.
C) one-to-one stochiometry.
D) reversibility.
E) affinity.

Question 30

What type of receptor does IP₃ bind?

A) G-protein coupled
B) ligand-gated Ca²⁺ channel
C) enzyme-linked
D) sensor kinase
E) phospholipase type-I

Question 31

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.

Question 32

All of the following are general components of the growth factor signaling pathway EXCEPT

A) tyrosine kinase-linked receptor.
B) GRB2-Sos-Ras complexes.
C) phosphorylated transcription factors.
D) Raf-1.
E) IP₃ and Ca²⁺.

Question 33

Which of the following is not an effect of epinephrine throughout the body?

A) Promotes the breakdown of glycogen in skeletal muscle cells
B) Relaxes lung airways
C) Stimulates heart muscle cells
D) A person feeling energized after drinking a cup of caffeinated coffee
E) The body's ability to digest a large meal

Question 34

Various cells in the body respond to the hormone epinephrine in various ways due to _____.

A) cellular respiration
B) metabolism
C) phosphodiesterase
D) protein kinases
E) differential gene regulation

Question 35

Which of the following is NOT an example of how differential gene regulation affects cellular response?

A) The expression of proteins that are controlled by signal transduction pathways may vary in different cell types.
B) Cell junctions passing ions between the cytosol of one cell to another cell.
C) A cell may or may not express a receptor for a particular signaling molecule.
D) The expression of proteins involved in intracellular signal transduction pathways may vary in different cell types
E) Different cell types have different cell surface receptors that recognize the same signaling molecules.

Question 36

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

Question 37

G proteins and Ras are activated when bound to guanosine diphosphate.

Question 38

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

Question 39

The type of cellular response that is caused by a given signaling molecule depends on the type of cell responding to the signal.

Question 40

Apoptosis can occur via both intrinsic and extrinsic pathways.

Question 41

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

Question 42

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