Deck 6: Cell Communication

Question 1

Which list describes the correct sequence of events involved in cell signaling?

A) Signal transduction, reception, signal transmission, response
B) Response, signal transduction, signal transmission, reception
C) Signal transmission, signal transduction, reception, response
D) Reception, signal transmission, response, signal transduction
E) Signal transmission, reception, signal transduction, response

Answer 1

E

Question 2

What type of chemical compound diffuses across synapses?

A) Neurons
B) Hormones
C) Steroids
D) Prostaglandins
E) Neurotransmitters

Answer 2

E

Question 3

What type of cells must receive, relay, and respond to the information signaled?

A) GABA
B) Integrins
C) Target cells
D) Local regulators
E) Neurotransmitters

Answer 3

C

Question 4

How are hormones produced by endocrine glands typically transported to target cells?

A) By the blood
B) Through the air
C) Across a synapse
D) Via direct contact
E) Through interstitial fluid

Question 5

What can happen when GABA binds to its receptor?

A) Neural signaling is inhibited.
B) Sodium ions enter the cell.
C) New signals are transmitted.
D) Muscle contraction is stimulated.
E) Enzyme-linked receptors are activated.

Question 6

The outer part of a G protein-linked receptor binds to a(n) ____, and its inner part binds to a(n) ____.

A) G protein; ion channel
B) G protein; tyrosine kinase
C) ion channel; G protein
D) signaling molecule; G protein
E) signaling molecule; tyrosine kinase

Question 7

Which statement about receptors is false ?

A) They are highly selective.
B) They are also called ligands.
C) They are proteins or glycoproteins.
D) They are found inside the cell and on the cell surface.
E) They are activated by binding to a signaling molecule.

Question 8

When food is scarce, the amoeba-like cellular slime mold, Dictyostelium , secretes which compound?

A) Glucocorticoid
B) Cyclic adenosine monophosphate
C) Estrogen
D) Insulin
E) Glucagon

Question 9

Most intracellular receptors are what type of protein?

A) DNA
B) Steroids
C) Enzymes
D) Neurotransmitters
E) Transcription factors

Question 10

Typically, the gate of an ion channel remains closed until a(n) ____ binds to the receptor.

A) ligand
B) enzyme
C) G protein
D) target cell
E) first messenger

Question 11

Suppose that acetylcholine binds its receptor on the surface of a muscle cell. What happens next?

A) A sodium gate opens.
B) G protein is activated.
C) Tyrosine is phosphorylated.
D) Tyrosine kinase is activated.
E) A neurotransmitter crosses the synapse.

Question 12

Which neurotransmitter opens ligand-gated sodium channels?

A) GABA
B) Cortisol
C) Ecdysone
D) Acetylcholine
E) Brassinosteroid

Question 13

Under which of the following situations would receptor downregulation most likely occur?

A) The number of G proteins is too high.
B) The concentration of a hormone is too high.
C) The cell is unable to manufacture cyclic AMP.
D) The concentration of a neurotransmitter is too low.
E) The number of receptors in the plasma membrane is too low.

Question 14

What is typically the result of receptor upregulation?

A) A hormone's signal is amplified.
B) The number of receptors decreases.
C) The sensitivity of a cell to a hormone decreases.
D) The number of genes that code for a receptor increases.
E) The concentration of hormone molecules in the blood increases.

Question 15

During enzyme-linked reception, signal molecules bind to two tyrosine kinase receptors. The receptor proteins move closer together in the plasma membrane and pair, forming a(n) ____.

A) gate
B) dimer
C) pathway
D) polypeptide chain
E) protein kinase cascade

Question 16

What transmits information electrically and chemically?

A) Receptors
B) Target cells
C) Neurons
D) Cell signaling
E) Hormones

Question 17

How is paracrine signaling different from other types of signaling?

A) The signaling molecules are hormones.
B) The signaling molecules release neurotransmitters.
C) The signaling molecules are displayed on the cell surface and interact with nearby cells.
D) The signaling molecules are transferred by electrical signals and act on nearby cells.
E) The signaling molecules are diffused through interstitial fluid and act on nearby cells.

Question 18

A receptor on the cell surface usually has several domains. What is the function of the external domain?

A) It functions as an enzyme.
B) It attaches the receptor to the DNA.
C) It holds the receptor within the membrane.
D) It transmits the signal to the inside of the cell.
E) It is the docking site for a signaling molecule.

Question 19

Which local regulator is stored in cells of the immune system and released during an allergic reaction?

A) Histamine
B) Nitric oxide
C) A growth factor
D) A prostaglandin
E) A neurotransmitter

Question 20

If the cells are physically close to one another, a signaling molecule on one cell may combine with a _________ on another cell.

A) ligand
B) vacuole
C) peripheral membrane protein
D) receptor
E) membrane

Question 21

What type of protein can transduce a signal in two directions?

A) Integrins
B) G proteins
C) Ras proteins
D) Scaffold proteins
E) Phosphorylated proteins

Question 22

The following are different types of neurotransmitters EXCEPT

A) serotonin.
B) norepinephrine.
C) acetylcholine.
D) cyclic adenosine.
E) dopamine.

Question 23

In the cAMP signal transduction pathway, a protein kinase is activated. What happens next?

A) G protein is activated.
B) GDP is replaced by GTP.
C) cAMP is converted to ATP.
D) Adenylyl cyclase is activated.
E) The protein kinase activates a cellular response.

Question 24

Where are calcium ions stored before a signaling pathway releases them into the cytosol?

A) Nucleus
B) Ribosome
C) Lysosome
D) Plasma membrane
E) Endoplasmic reticulum

Question 25

Phosphodiesterase catalyzes the conversion of

A) IP₃ to PIP₂.
B) GDP to GTP.
C) cAMP to AMP.
D) calcium to calcium-calmodulin.
E) a protein to a phosphorylated protein.

Question 26

What is calmodulin?

A) A hormone
B) A phosphatase
C) A phospholipase
D) A protein kinase
E) A calcium-binding protein

Question 27

Which molecule is a first messenger but not a second messenger?

A) G protein
B) Cyclic AMP
C) Acetylcholine
D) Protein kinase
E) Adenylyl cyclase

Question 28

The process of receiving an incoming signal is known as _______.

A) signal transduction
B) receptor
C) reception
D) signal transmission
E) response

Question 29

Which statement about G protein is false ?

A) Its subunits can separate.
B) One subunit is a GTPase.
C) One subunit binds GTP.
D) One subunit binds GDP.
E) One subunit binds ATP.

Question 30

Where are hormones produced in animals?

A) Blood cells
B) Endocrine glands
C) Skin cells
D) Neuron cells
E) Exocrine glands

Question 31

The hydrolysis of GTP to GDP deactivates the ____.

A) cAMP
B) G protein
C) Ras protein
D) ligand-gated channel
E) protein kinase pathway

Question 32

Adenylyl cyclase catalyzes the reaction in which

A) PIP₂ is split.
B) ATP is converted to cAMP.
C) GTP is converted to GDP.
D) a protein is phosphorylated.
E) calcium ions bind calmodulin.

Question 33

Scaffold proteins ensure that signals are relayed ____.

A) slowly
B) efficiently
C) inaccurately
D) methodically
E) simultaneously

Question 34

Which is an example of a second messenger?

A) Protein kinase A
B) An ion channel
C) Cyclic AMP
D) GABA
E) Insulin

Question 35

Which is a major group of enzyme-linked receptors?

A) G proteins
B) Ion channels
C) Tyrosine kinases
D) Phospholipases
E) Adenylyl cyclases

Question 36

During signal transduction of a G protein, the first messenger binds to the receptor, and the G protein is activated. What happens next?

A) Formation of cAMP
B) Cellular response
C) Activation of protein kinase
D) Activation of adenylyl cyclase
E) Phosphorylation of the G protein

Question 37

What activates protein kinase C?

A) IP₃
B) DAG
C) cAMP
D) PIP₂
E) Calcium ions

Question 38

In the IP₃ pathway, what is the function of IP₃?

A) Activates protein kinase C
B) Activates phospholipase C
C) Phosphorylates a protein
D) Binds calcium channels in the ER
E) Activates adenylyl cyclase

Question 39

What is found between adjacent plant cells that allows signal molecules to pass quickly from one cell to another?

A) Prostaglandins
B) Plasmodesmata
C) Paracrine regulation
D) Neurotransmitters
E) Endocrine glands

Question 40

In the phospholipase C signal transduction pathway, which pair of second messengers is produced?

A) IP₃ and DAG
B) PIP₂ and IP₃
C) cAMP and IP₃
D) Phospholipase C and protein kinase A
E) Phospholipase C and G protein

Question 41

What is the process in which one activated receptor can give rise to thousands of final products?

A) Signal transcription
B) Signal transmission
C) Signal transduction
D) Signal termination
E) Signal amplification

Question 42

Compare local regulators, neurotransmitters, and hormones. Identify examples of each type of signaling molecule.

Question 43

Insulin stimulates cells to take in glucose by facilitated diffusion, so the down regulation of insulin receptors increases the ability of cells to take in glucose. __________________

Question 44

The gas ethylene is a plant hormone that regulates a variety of processes, including seed germination and ripening of fruit.

Question 45

Which is a part of a signal transduction pathway that enables vision in dim light in vertebrates?

A) Acetylcholine
B) Histamine
C) Brassinosteroids
D) Rhodopsin
E) Phosphorylation

Question 46

When an enzyme-linked receptor is activated, a conformational change activates the extracellular kinases.

Question 47

The main signaling cascade for cell division and differentiation is the ____ cascade.

A) cAMP
B) MAP kinase
C) phosphoinositol
D) phospholipase C
E) calcium-calmodulin

Question 48

When food is abundant , the cellular slime mold Dictyostelium secretes cAMP into the environment to signal the formation of a multicellular slug-shaped colony.
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Question 49

Ion channels are found in the plasma membranes of neurons and muscle cells.

Question 50

Which statement about Ras proteins is false ?

A) They are G proteins.
B) They include MAP kinases.
C) They are active when bound to GTP.
D) They are inactivated when phosphorylated.
E) They are activated by tyrosine kinase receptors.

Question 51

Briefly describe calmodulin and its role in signal transduction.

Question 52

What happens when Ras proteins become stuck in their "on" state?

A) Cellular responses are slowed down.
B) Additional ions are catalyzed.
C) There is unregulated cell division.
D) There is an increase in protein synthesis.
E) Ligand-gated channels close off the membrane.

Question 53

What is the difference between a first messenger and a second messenger? Give an example of each.

Question 54

Using growth factor binding to its tyrosine kinase receptor as an example, explain the four main steps in cell signaling.

Question 55

You conduct an experiment in which you inactivate Ras proteins in fibroblast cells. Which of the following is the most immediate consequence of this procedure?

A) The fibroblasts divide uncontrollably.
B) The fibroblasts synthesize excess DAG.
C) The fibroblasts synthesize excess G protein.
D) The fibroblasts no longer respond to calmodulin.
E) The fibroblasts no longer synthesize DNA in response to growth factors.

Question 56

Choanoflagellates are important in the study of cell communication evolution because choanoflagellates have

A) protein kinases similar to those in animals.
B) G proteins different from those in prokaryotes.
C) signaling molecules similar to those of other protists.
D) signal transduction pathways unlike those in other bacteria.
E) signal transduction pathways that interfere with the cells they infect.

Question 57

Describe the part of the cell where polar and nonpolar signaling molecules bind to their respective receptor. Explain your reasoning.

Question 58

When a signaling molecule binds to a G protein-linked receptor, the ligand-receptor complex associates with GDP protein and causes GDP to be replaced by GTP.  __________________

Question 59

The outer part of the enzyme-linked receptor has a binding site for a signaling molecule, and the part of the receptor that extends into the cytosol has a binding site for a specific G protein.
__________________

Question 60

A local regulator is a signaling molecule that diffuses through the interstitial fluid, the fluid surrounding the cells, and acts on nearby cells. What is this process?

A) Paracrine regulation
B) Endocrine distortion
C) Prostaglandin absorption
D) Marrow alignment
E) Redox reaction

Question 61

Briefly, describe three examples of how cells respond to signals. Describe two possible mechanisms of signal termination.

Question 62

Compare the structure and function of ion channel-linked receptors, G protein-linked receptors, and enzyme-linked receptors.

Question 65

Compare the signal transduction pathway involving cAMP with that involving phospholipids.

Question 66

G protein-linked receptors are transmembrane proteins with a binding site for a signaling molecule outside the cell and a neuron component inside the cell.

Question 67

Scaffold proteins organize groups of intracellular signaling kinases into signaling complexes.

Question 68

What is meant by signal amplification? Provide two examples.

Question 70

Barbiturates and benzodiazepine drugs bind to GABA receptors to open chloride channels, inhibit neural impulse, and induce tranquility.
__________________
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Question 73

The addictive component in cigarettes is nicotine. Explain the effect of excess nicotine on nicotine receptor (also called the nicotinic acetylcholine receptor) expression level. How would this upregulation or downregulation of the nicotine receptor occur? Could this explain withdrawal to nicotine?