Question 1

What is the name of a calcium-binding protein that acts in conjunction with calcium to bring about the responses associated with cytoplasmic rises in calcium ion concentration?
A)calpectin
B)calmodulin
C)calcariain
D)callistin
E)modulocalcin

Accepted Answer

Calmodulin is a calcium-binding protein that acts in conjunction with calcium to bring about various responses associated with cytoplasmic rises in calcium ion concentration. It is involved in several cellular processes such as muscle contraction, regulation of enzyme activity, and gene expression. The other options (calpectin, calcariain, callistin, and modulocalcin) are not calcium-binding proteins and do not have a role in calcium-mediated responses.

Question 2

What part of an insulin-receptor substrate binds to tyrosine phosphorylation sites on the activated insulin receptor?
A)an N-terminal PH domain
B)a PTB domain
C)a long tail containing tyrosine phosphorylation sites
D)a C-terminal PH domain
E)a PKB domain

Accepted Answer

A PTB (phosphotyrosine-binding) domain is known to bind to tyrosine phosphorylation sites on the activated insulin receptor.

Question 3

Ora1 is a tetrameric _______ that has been identified as being involved in a particular type of inherited human immune deficiency that results from a lack of Ca2+ stores in ________. A)Ca^2+--ion channel,B lymphocytes B)Ca^2+--ion pump,B lymphocytes C)Ca^2+-ion channel,T lymphocytes D)Ca^2+--ion pump,T lymphocytes E)Ca^2+--ion channel,macrophages

Accepted Answer

Ora1 is a tetrameric Ca²⁺-ion channel involved in store-operated calcium entry in T lymphocytes, and its dysfunction can lead to immune deficiencies.

Question 4

What is responsible for deactivating glycogen synthase kinase-3?
A)its phosphorylation by PKB
B)its dephosphorylation by protein phosphatase 1
C)its dephosphorylation by PKB
D)its phosphorylation by protein phosphatase 1
E)its degradation by PKB

Accepted Answer

Glycogen synthase kinase-3 is deactivated when it is phosphorylated by PKB (also known as Akt). This phosphorylation inhibits the activity of glycogen synthase kinase-3 and allows for the activation of glycogen synthase, leading to glycogen synthesis. Dephosphorylation of glycogen synthase kinase-3 by protein phosphatase 1 would actually activate the enzyme, making choice B incorrect. PKB does not directly cause the degradation of glycogen synthase kinase-3, so choice E is also incorrect.

Question 5

Which of the following signaling methods is not found in plants but is present in other eukaryotes? A)MAP kinase pathway B)Ca²⁺ signaling C)phosphoinositide signaling D)cyclic nucleotides E)extracellular receptors

Accepted Answer

Cyclic nucleotide signaling is less prominent in plants compared to other eukaryotes, where it plays a significant role in processes like vision and heart rate regulation.

Question 6

Two $\alpha$$\beta$ heterodimers of the insulin receptor are held together by ____ between the _______.
A)ionic bonds,$\alpha$ chains
B)ionic bonds,$\beta$ chains
C)disulfide bonds,$\alpha$chains
D)disulfide bonds,$\beta$ chains
E)disulfide bonds,$\alpha$ chain of one heterodimer and the  chain of the other

Accepted Answer

The answer of Two $\alpha$$\beta$ heterodimers of the insulin receptor...

Question 7

What is the reason for the withdrawal of cells from the cell cycle after exposure to stressful stimuli,like X-rays and damaging chemicals?
A)It gives the cell time to repair damage resulting from such adverse conditions.
B)It allows the cell to initiate programmed cell death.
C)It allows cells to initiate sodium transport.
D)It allows the cell to secrete defensive chemicals.
E)It gives the cell time to switch its developmental pathways.

Accepted Answer

When cells are exposed to stressful stimuli like X-rays and damaging chemicals, they may suffer DNA damage or other cellular damage. Withdrawing from the cell cycle enables the cell to focus its resources on repairing the damage before proceeding with cell division. This helps ensure that the damage is not propagated to daughter cells.

Question 8

Specificity in MAP kinase pathways is sometimes achieved by spatial localization of the pathway's component proteins.Spatial localization of these components is done by structural (i.e.,nonenzymatic)proteins called _____________.
A)sequestration proteins
B)partitioning proteins
C)scaffolding proteins
D)framework proteins
E)spatial organization proteins

Accepted Answer

Spatial localization of MAP kinase pathway components is achieved by scaffolding proteins, which aid in the assembly of the pathway components into functional complexes at specific sites within the cell.

Question 9

Among the agents that can cause ryanodine receptors to open are _______ ions,in a phenomenon called _______.
A)calcium,calcium-integrated calcium release
B)calcium,calcium-induced calcium release
C)potassium,potassium-induced calcium release
D)chlorine,chlorine-induced calcium release
E)copper,copper-induced calcium release

Accepted Answer

Ryanodine receptors are calcium channels that are activated by calcium-induced calcium release, where the initial influx of calcium causes further release of calcium from intracellular stores through these receptors. Therefore, the only option that includes calcium as both the agent that opens the receptors and the phenomenon that occurs is B: calcium-induced calcium release.

Question 10

Type I diabetes is caused by ________.
A)degradation of insulin in the bloodstream
B)an inability to produce insulin
C)a decrease in the ability of target cells for insulin to respond to the presence of the hormone
D)insulin resistance
E)an overproduction of insulin

Accepted Answer

Type I diabetes is an autoimmune disease in which the immune system attacks and destroys the insulin-producing beta cells in the pancreas, leading to an inability to produce insulin.

Question 11

In cells exposed to stressful stimuli,like X-rays or damaging chemicals,what response does the MAP kinase cascade coordinate?
A)cell proliferation
B)withdrawal from the cell cycle
C)rapid differentiation
D)slowing of the Krebs cycle
E)a loss of sensory ability

Accepted Answer

The MAP kinase cascade is known to coordinate the signal transduction in cells that are exposed to stressful stimuli. One of the key roles of this cascade is to trigger the withdrawal of cells from the cell cycle, which is an important mechanism that allows cells to conserve energy and resources in response to stress. This process is thought to be mediated by the activation of several different downstream effectors, including p53, p21, and Rb, which work together to halt the cell cycle and prevent proliferation of damaged cells.

Question 12

What is activated by calcium ions entering an egg cell just after fertilization?
A)protein kinase A
B)insulin
C)cyclin-dependent kinases that drive the zygote toward its first mitotic division
D)cyclin-dependent kinases that drive the zygote toward its first meiotic division
E)glucagon-dependent kinases that drive the zygote toward its first mitotic division

Accepted Answer

Calcium ions entering an egg cell just after fertilization activate cyclin-dependent kinases that drive the zygote toward its first mitotic division. This is because calcium triggers the release of the second meiotic arrest and initiates the embryonic cell cycle. Protein kinase A, insulin, and glucagon-dependent kinases are not directly involved in this process.

Question 13

How is the distribution of free calcium ions in the living cell detected?
A)fluorescent probes that emit light in the presence of calcium ions
B)antibodies bound to ferritin
C)an electron microscope
D)autoradiography and the distribution of radioisotope
E)NMR imaging

Accepted Answer

Fluorescent probes that emit light in the presence of calcium ions are commonly used to detect the distribution of free calcium ions in living cells. The probes are designed to bind specifically to calcium ions and emit a fluorescent signal when bound, which can be detected using fluorescence microscopy.

Question 14

Accessory proteins that bind to inactive monomeric G proteins and stimulate dissociation of the bound GDP are called:
A)GAPs
B)GEFs
C)GDIs
D)RASps
E)MAPs

Accepted Answer

Accessory proteins that bind to inactive monomeric G proteins and stimulate dissociation of the bound GDP are called guanine nucleotide exchange factors or GEFs. GAPs (A) stimulate GTP hydrolysis by the activated G protein, GDIs (C) prevent nucleotide exchange and stabilize inactive G proteins, RASps (D) are hypothetical proteins not known to exist, and MAPs (E) are proteins involved in intracellular signaling pathways.

Question 15

The enzyme below that has been identified as a negative regulator of glycogen synthase is ______.
A)glycogen phosphorylase
B)glycogen phosphorylase kinase
C)glycogen synthase kinase-3
D)insulin synthase kinase
E)protein kinase A

Accepted Answer

Glycogen synthase kinase-3 is a well-known negative regulator of glycogen synthase. It inhibits glycogen synthase by phosphorylating it at specific sites.

Question 16

What generally triggers the release of calcium ions by ryanodine receptors? A)potassium efflux B)sodium influx C)an action potential D)IP₃ release E)IP₃ uptake

Accepted Answer

The release of calcium ions by ryanodine receptors is generally triggered by an action potential.

Question 17

Accessory proteins that maintain monomeric G proteins in an inactive state by inhibiting GDP-GTP exchange are called:
A)GAPs
B)GEFs
C)GDIs
D)RASps
E)MAPs

Accepted Answer

GDIs (Guanine nucleotide Dissociation Inhibitors) are accessory proteins that bind to and stabilize the GDP-bound form of monomeric G proteins. This prevents GDP-GTP exchange and keeps the G protein in an inactive state. GAPs (GTPase Activating Proteins) promote the hydrolysis of GTP to GDP and assist in turning off the active G protein. GEFs (Guanine nucleotide Exchange Factors) facilitate the exchange of GDP for GTP and activate the G protein. RASps and MAPs are not relevant to this process.

Question 18

How is Ras activity turned off?
A)It is turned off by phosphorylation.
B)It is turned off by hydrolysis of its bound GTP to GDP.
C)It is turned off by hydrolysis of its bound GDP to GTP.
D)It is turned off by an allosteric inhibitor.
E)It is turned off by hydrolysis of its bound GTP to GMP.

Accepted Answer

Ras activity is turned off by hydrolysis of its bound GTP to GDP, which is catalyzed by GTPase-activating proteins (GAPs). This process is essential for regulating cellular signaling pathways and preventing abnormal activation of signaling cascades.

Question 19

The concentration of calcium ions in the ER lumen,the plant cell vacuole and the extracellular space are on average more than _______ times higher than in the cytosol.
A)10
B)100
C)1,000
D)10.000
E)1,000,000

Accepted Answer

The concentration of calcium ions in the ER lumen, the plant cell vacuole, and the extracellular space is on average more than 10,000 times higher than in the cytosol. This is due to the important roles of calcium ions in signal transduction and regulation of cellular processes, making it necessary to maintain such high concentrations in specific compartments.

Question 20

Following a nerve impulse,what triggers the opening of plasma membrane voltage-gated Ca2+ channels? A)membrane hyperpolarization B)binding of an appropriate ligand C)membrane depolarization D)membrane hypopolarization E)binding of K⁺ ions

Accepted Answer

Membrane depolarization triggers the opening of plasma membrane voltage-gated Ca2+ channels.

Quiz 15: Cell Signaling and Signal Transduction: Communication Between Cells

What is the name of a calcium-binding protein that acts in conjunction with calcium to bring about the responses associated with cytoplasmic rises in calcium ion concentration?

What part of an insulin-receptor substrate binds to tyrosine phosphorylation sites on the activated insulin receptor?

Ora1 is a tetrameric _ that has been identified as being involved in a particular type of inherited human immune deficiency that results from a lack of Ca2+ stores in __.

What is responsible for deactivating glycogen synthase kinase-3?

Which of the following signaling methods is not found in plants but is present in other eukaryotes?

Two $\alpha$ $\beta$ heterodimers of the insulin receptor are held together by between the ___.

What is the reason for the withdrawal of cells from the cell cycle after exposure to stressful stimuli,like X-rays and damaging chemicals?

Specificity in MAP kinase pathways is sometimes achieved by spatial localization of the pathway's component proteins.Spatial localization of these components is done by structural (i.e.,nonenzymatic) proteins called _____________.

Among the agents that can cause ryanodine receptors to open are _ ions,in a phenomenon called _.

Type I diabetes is caused by ________.

In cells exposed to stressful stimuli,like X-rays or damaging chemicals,what response does the MAP kinase cascade coordinate?

What is activated by calcium ions entering an egg cell just after fertilization?

How is the distribution of free calcium ions in the living cell detected?

Accessory proteins that bind to inactive monomeric G proteins and stimulate dissociation of the bound GDP are called:

The enzyme below that has been identified as a negative regulator of glycogen synthase is ______.

What generally triggers the release of calcium ions by ryanodine receptors?

Accessory proteins that maintain monomeric G proteins in an inactive state by inhibiting GDP-GTP exchange are called:

How is Ras activity turned off?

The concentration of calcium ions in the ER lumen,the plant cell vacuole and the extracellular space are on average more than _______ times higher than in the cytosol.

Following a nerve impulse,what triggers the opening of plasma membrane voltage-gated Ca2+ channels?