Question 1

What happens to cells if the receptors are degraded once they are internalized?

Accepted Answer

A) The cells are able to make a magnified response to the same stimulus from the ligand in question. 
B) The cells permanently lose sensitivity for the ligand in question. 
C) The cells lose,at least temporarily,sensitivity for the ligand in question. 
D) The cells remain sensitive to the ligand in question. 
E) The cells expand. 
A) The cells are able to make a magnified response to the same stimulus from the ligand in question. 
B) The cells permanently lose sensitivity for the ligand in question. 
C) The cells lose,at least temporarily,sensitivity for the ligand in question. 
D) The cells remain sensitive to the ligand in question. 
E) The cells expand.

Question 2

Which of the following supports the ligand-mediated model of receptor dimerization?

Accepted Answer

A) Some growth and differentiation factors like PDGF or CSF-1 are composed of two similar or identical disulfide-linked subunits,each of which has a binding site for a receptor. 
B) Ligands have been found to be small proteins. 
C) Ligands have been found to be steroid hormones. 
D) Ligands were found to bind to each other 
E) Receptors have been shown to have multiple binding sites for ligands. 
A) Some growth and differentiation factors like PDGF or CSF-1 are composed of two similar or identical disulfide-linked subunits,each of which has a binding site for a receptor. 
B) Ligands have been found to be small proteins. 
C) Ligands have been found to be steroid hormones. 
D) Ligands were found to bind to each other 
E) Receptors have been shown to have multiple binding sites for ligands.

Question 3

What inorganic gas has been shown to act as a second messenger that relaxes the smooth muscles of blood vessels?

Accepted Answer

A) NO 
B) N2O 
C) nitrous oxide 
D) CO 
E) N2 
A) NO 
B) N2O 
C) nitrous oxide 
D) CO 
E) N2

Question 4

What does the interaction between arrestin and clathrin promote?

Accepted Answer

A) the uptake of free hormone 
B) the uptake of phosphorylated GPCRs into the cell by exocytosis 
C) the uptake of phosphorylated GPCRs into the cell by endocytosis 
D) the expulsion of phosphorylated GPCRs from the cell by exocytosis 
E) the secretion of GPCRs 
A) the uptake of free hormone 
B) the uptake of phosphorylated GPCRs into the cell by exocytosis 
C) the uptake of phosphorylated GPCRs into the cell by endocytosis 
D) the expulsion of phosphorylated GPCRs from the cell by exocytosis 
E) the secretion of GPCRs

Question 5

What agent made by endothelial cells makes blood vessel smooth muscle cells relax?

Accepted Answer

A) nitrous oxide 
B) acetylcholine 
C) nitric oxide 
D) cAMP 
E) cGMP 
A) nitrous oxide 
B) acetylcholine 
C) nitric oxide 
D) cAMP 
E) cGMP

Question 6

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

Accepted Answer

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. 
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.

Question 7

How many high-affinity sweet-taste receptors have been identified?

Accepted Answer

A) none 
B) 30 
C) 1 
D) 10 
E) 3 
A) none 
B) 30 
C) 1 
D) 10 
E) 3

Question 8

Where is the guanine nucleotide-binding site of the G protein located?

Accepted Answer

A) on the G  $\alpha$  subunit 
B) on the G $\beta$  subunit 
C) on the G $\gamma$ subunit 
D) on the G $\beta$ $\gamma$  subunit 
E) on all three subunits 
A) on the G  $\alpha$  subunit 
B) on the G $\beta$  subunit 
C) on the G $\gamma$ subunit 
D) on the G $\beta$ $\gamma$  subunit 
E) on all three subunits

Question 9

What enzyme below does diacylglycerol (DAG)recruit and activate?

Accepted Answer

A) phosphatidylinositol (PI)-specific phospholipase C-$\beta$ 
B) protein kinase A 
C) protein kinase C 
D) glycogen phosphorylase 
E) phosphorylase kinase 
A) phosphatidylinositol (PI)-specific phospholipase C-$\beta$ 
B) protein kinase A 
C) protein kinase C 
D) glycogen phosphorylase 
E) phosphorylase kinase

Question 10

Which of the following is (are)not characteristics of the pathways activated by second messengers?

Accepted Answer

A) Each signaling pathway consists of a series of distinct proteins that operate in sequence. 
B) Each protein in the pathway typically acts by altering the conformation of the previous (upstream)protein in the series,an event that activates or inhibits the protein. 
C) Alterations in the conformations of signaling proteins are often accomplished by protein kinases and protein phosphatases that,respectively,add or remove phosphate groups from other proteins. 
D) Some phosphatases and protein kinases in the pathway have numerous proteins as their substrates; others act on only a single protein substrate or a single amino acid of a protein substrate. 
E) Many of the protein substrates of the pathway enzymes are enzymes themselves,like other kinases and phosphatases,but they include ion channels,transcription factors and various regulatory molecules. 
A) Each signaling pathway consists of a series of distinct proteins that operate in sequence. 
B) Each protein in the pathway typically acts by altering the conformation of the previous (upstream)protein in the series,an event that activates or inhibits the protein. 
C) Alterations in the conformations of signaling proteins are often accomplished by protein kinases and protein phosphatases that,respectively,add or remove phosphate groups from other proteins. 
D) Some phosphatases and protein kinases in the pathway have numerous proteins as their substrates; others act on only a single protein substrate or a single amino acid of a protein substrate. 
E) Many of the protein substrates of the pathway enzymes are enzymes themselves,like other kinases and phosphatases,but they include ion channels,transcription factors and various regulatory molecules.

Question 11

The process that blocks active receptors from turning on additional G proteins is called ________.

Accepted Answer

A) hypersensitization 
B) desensitization 
C) hyposensitization 
D) deactivation 
E) sensitivitization 
A) hypersensitization 
B) desensitization 
C) hyposensitization 
D) deactivation 
E) sensitivitization

Question 12

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

Accepted Answer

A) glycogen phosphorylase 
B) glycogen phosphorylase kinase 
C) glycogen synthase kinase-3 
D) insulin synthase kinase 
E) protein kinase A 
A) glycogen phosphorylase 
B) glycogen phosphorylase kinase 
C) glycogen synthase kinase-3 
D) insulin synthase kinase 
E) protein kinase A

Question 13

What is the origin of virtually all of the signals that regulate cellular activities?

Accepted Answer

A) the cell surface 
B) the nucleus 
C) the nucleolus 
D) the endoplasmic reticulum 
E) the cell wall 
A) the cell surface 
B) the nucleus 
C) the nucleolus 
D) the endoplasmic reticulum 
E) the cell wall

Question 14

Bcl-2 acts as a(n)________ by promoting ___________.

Accepted Answer

A) oncogene,cell division 
B) haplogene,survival of potential cancer cells that would otherwise die by apoptosis 
C) oncogene,survival of potential cancer cells that would otherwise die by apoptosis 
D) cancer gene,survival of potential cancer cells that would otherwise die by apoptosis 
E) haplogene,cell division 
A) oncogene,cell division 
B) haplogene,survival of potential cancer cells that would otherwise die by apoptosis 
C) oncogene,survival of potential cancer cells that would otherwise die by apoptosis 
D) cancer gene,survival of potential cancer cells that would otherwise die by apoptosis 
E) haplogene,cell division

Question 15

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

Accepted Answer

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 
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

Question 16

In which of the following biological processes is nitric oxide not involved?

Accepted Answer

A) anticoagulation 
B) neurotransmission 
C) smooth muscle relaxation 
D) visual perception 
E) hearing 
A) anticoagulation 
B) neurotransmission 
C) smooth muscle relaxation 
D) visual perception 
E) hearing

Question 17

Which molecule below does not act as a neurotransmitter and a hormone?

Accepted Answer

A) glutamate 
B) glycine 
C) dopamine 
D) eicosanoids 
E) thyroid hormone 
A) glutamate 
B) glycine 
C) dopamine 
D) eicosanoids 
E) thyroid hormone

Question 18

What allows receptors for extracellular signaling molecules present on the responding cell's surface to recognize such molecules so readily?

Accepted Answer

A) They bind the signaling molecules with low affinity. 
B) They bind the signaling molecules with high affinity. 
C) They denature the signaling molecules. 
D) They stabilize the signaling molecules. 
E) They infiltrate the signaling molecules. 
A) They bind the signaling molecules with low affinity. 
B) They bind the signaling molecules with high affinity. 
C) They denature the signaling molecules. 
D) They stabilize the signaling molecules. 
E) They infiltrate the signaling molecules.

Question 19

Which of the following features would be a requirement for a receptor that exhibits ligand-mediated dimerization?

Accepted Answer

A) The ligand has only one binding site for receptors. 
B) The ligand has two binding sites for receptors. 
C) The receptor must have a phenylalanine residue in a specific location. 
D) The receptor must have a molecular weight of 50,000 daltons. 
E) Ligand binding causes a conformational shift that reveals a binding site for another receptor. 
A) The ligand has only one binding site for receptors. 
B) The ligand has two binding sites for receptors. 
C) The receptor must have a phenylalanine residue in a specific location. 
D) The receptor must have a molecular weight of 50,000 daltons. 
E) Ligand binding causes a conformational shift that reveals a binding site for another receptor.

Question 20

What phosphorylates the tyrosine residues found on docking proteins?

Accepted Answer

A) a G protein coupled receptor 
B) a receptor protein-tyrosine kinase 
C) a cytoplasmic protein-tyrosine kinase 
D) adaptor proteins 
E) receptor protein phosphatases 
A) a G protein coupled receptor 
B) a receptor protein-tyrosine kinase 
C) a cytoplasmic protein-tyrosine kinase 
D) adaptor proteins 
E) receptor protein phosphatases

What happens to cells if the receptors are degraded once they are internalized?

Which of the following supports the ligand-mediated model of receptor dimerization?

What inorganic gas has been shown to act as a second messenger that relaxes the smooth muscles of blood vessels?

What does the interaction between arrestin and clathrin promote?

What agent made by endothelial cells makes blood vessel smooth muscle cells relax?

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

How many high-affinity sweet-taste receptors have been identified?

Where is the guanine nucleotide-binding site of the G protein located?

What enzyme below does diacylglycerol (DAG)recruit and activate?

Which of the following is (are)not characteristics of the pathways activated by second messengers?

The process that blocks active receptors from turning on additional G proteins is called ________.

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

What is the origin of virtually all of the signals that regulate cellular activities?

Bcl-2 acts as a(n) by promoting ___.

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

In which of the following biological processes is nitric oxide not involved?

Which molecule below does not act as a neurotransmitter and a hormone?

What allows receptors for extracellular signaling molecules present on the responding cell's surface to recognize such molecules so readily?

Which of the following features would be a requirement for a receptor that exhibits ligand-mediated dimerization?

What phosphorylates the tyrosine residues found on docking proteins?

Introduction to the Study of Cell and Molecular Biology

The Chemical Basis of Life

Bioenergetics,enzymes and Metabolism

The Structure and Function of the Plasma Membrane

Aerobic Respiration and the Mitochondrion

Photosynthesis and the Chloroplast

Interactions Between Cells and Their Environment

Cytoplasmic Membrane Systems: Structure, function, and Membrane Trafficking

The Cytoskeleton and Cell Motility

The Nature of the Gene and the Genome

Gene Expression: From Transcription to Translation

Control of Gene Expression

Dna Replication and Repair

Cellular Reproduction

Cancer

The Immune Response

Techniques in Cell and Molecular Biology

Filters

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

What happens to cells if the receptors are degraded once they are internalized?

Which of the following supports the ligand-mediated model of receptor dimerization?

What inorganic gas has been shown to act as a second messenger that relaxes the smooth muscles of blood vessels?

What does the interaction between arrestin and clathrin promote?

What agent made by endothelial cells makes blood vessel smooth muscle cells relax?

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

How many high-affinity sweet-taste receptors have been identified?

Where is the guanine nucleotide-binding site of the G protein located?

What enzyme below does diacylglycerol (DAG)recruit and activate?

Which of the following is (are)not characteristics of the pathways activated by second messengers?

The process that blocks active receptors from turning on additional G proteins is called ________.

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

What is the origin of virtually all of the signals that regulate cellular activities?

Bcl-2 acts as a(n)________ by promoting ___________.

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

In which of the following biological processes is nitric oxide not involved?

Which molecule below does not act as a neurotransmitter and a hormone?

What allows receptors for extracellular signaling molecules present on the responding cell's surface to recognize such molecules so readily?

Which of the following features would be a requirement for a receptor that exhibits ligand-mediated dimerization?

What phosphorylates the tyrosine residues found on docking proteins?

Introduction to the Study of Cell and Molecular Biology

The Chemical Basis of Life

Bioenergetics,enzymes and Metabolism

The Structure and Function of the Plasma Membrane

Aerobic Respiration and the Mitochondrion

Photosynthesis and the Chloroplast

Interactions Between Cells and Their Environment

Cytoplasmic Membrane Systems: Structure, function, and Membrane Trafficking

The Cytoskeleton and Cell Motility

The Nature of the Gene and the Genome

Gene Expression: From Transcription to Translation

Control of Gene Expression

Dna Replication and Repair

Cellular Reproduction

Cancer

The Immune Response

Techniques in Cell and Molecular Biology

Filters

Bcl-2 acts as a(n) by promoting ___.