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Chapter 11 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

The stage of cell signaling in which the signal is converted to a form that can bring about a response in the cell is called

A

Transduction

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2
Q

Second messengers tend to be small and water-soluble. This accounts for their ability to

A

Rapidly move throughout the cell by diffusion

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3
Q

What effect does ligand binding have on receptor tyrosine kinase proteins?

A

Ligand binding causes them to phosphorylate and form dimers

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4
Q

A difference between the mechanisms of cAMP and Ca2+ in signal transduction is that __ and Ca2+ __

A

cAMP is synthesized by an enzyme in response to a signal and Ca2+ is released from intercellular stores

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5
Q

What happens during the process of paracrine signaling?

A

Numerous cells simultaneously receive and respond to the molecules of growth factor produced by a single cell in their vicinity

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6
Q

In a phosphorylation cascade, __ phosphorylate proteins, and __ dephosphorylate them

A

Protein kinases

Protein phosphates

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7
Q

What is the general name for an enzyme that transfers phosphate groups from ATP to other molecules?

A

Protein kinase

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8
Q

In which part of the cell are calcium ions usually found?

A

Endoplasmic reticulum

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9
Q

cAMP usually directly activates

A

Protein kinase A

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10
Q

Second messenger

A

Small, nonprotein components of signal transduction pathways

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11
Q

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

A

They amplify the original signal manifold

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12
Q

Phosphorylatation cascade

A

When relay molecules in signal transduction pathways are protein kinases and they act on other protein kinases in the pathway
-amplified the original signal many times over because each kinase in the cascade can act on many molecules of its substrate

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13
Q

Certain yeast cells secrete a molecule called the -factor. The purpose of this molecule is to

A

Stimulate an a yeast cell to grow toward the cell

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14
Q

Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence?

A

Nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cell’s nucleus

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15
Q

A number of important signaling molecules can enter cells through the plasma membrane because

A

They are either hydrophobic enough or small enough to cross the hydrophobic interior of the membrane

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16
Q

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

A

They amplify the original signal manifold

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17
Q

After a signaling molecule binds to a G protein-coupled receptor, what activates the associated G protein?

A

GTP displaces GDP on the G protein

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18
Q

Protein kinase

A

An enzyme that transfers phosphate groups from ATP to a protein

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19
Q

What happens in a phosphorylation cascade?

A

A series of different proteins in a pathway are phosphorylated in turn, each protein adding a phosphate group to the next one in line

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20
Q

Protein phosphates

A

Enzymes that can rapidly remove phosphate groups from proteins — dephosphorylation
Turns off the signal transduction pathway when the initial signal is no longer present
Also make the protein kinases reusable, enabling the cell to respond again to an extra cellular signal

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21
Q

What is the general name for an enzyme that transfers phosphate groups from ATP to other molecules?

A

Protein kinase

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22
Q

Kinase

A

Any enzyme that catalyzes the transfer of phosphate groups

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23
Q

Tyrosine kinase

A

An enzyme that catalyzes the transfer of a phosphate group from ATP to the amino acid tyrosine on a substrate protein

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24
Q

In which part of the cell are calcium ions usually found?

A

Endoplasmic reticulum

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25
Q

What happens during the process of paracrine signaling?

A

Numerous cells simultaneously receive and respond to the molecules of growth factor produced by a single cell in their vicinity

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26
Q

Cell-to-cell recognition

A

Communication between adjacent cells occurs between membrane-bound cell-surface molecules

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27
Q

Synaptic signaling

A

Molecules diffuse across the synapse between adjacent nerve cells

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28
Q

Hormonal signaling
Long distance signaling
Endocrine signaling

A

Specialized cells release hormone molecules, which travel via the circulatory system to other parts of the body, where they reach target cells that can recognize and respond to the hormones

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29
Q

Paracrine signaling is a type of

A

Local signaling in animals

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30
Q

Growth factors

A

Stimulate nearby target cells to grow and divide

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31
Q

The stage in which a chemical signal is detected when the signaling molecule binds to a receptor protein located at the cell’s surface is called

A

Reception

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32
Q

Transduction

A

The signal is converted to a form that can bring about a cellular response

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33
Q

Process of cell signaling

A

Reception
Transduction
Response

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34
Q

Reception

A

Target cell’s detection of a signaling molecule coming from outside the cell

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35
Q

Process of transduction

A

The binding of the signaling molecule changes the receptor protein in some way and initiates the process

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36
Q

Transduction stage converts

A

The signal to a form that can bring about a specific cellular response

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37
Q

Third stage of cell signaling (Response)

A

The transduced signal finally triggers a specific cellular response

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38
Q

Glycogen metabolism in liver cells

A

The hormone epinephrine binds to a specific receptor on the plasma membrane of the liver cell

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39
Q

A small G protein located at the plasma membrane. Cancer cells divide uncontrollably.
What change occurred?

A

A mutation that means Ras cannot hydrolyze GTP to GDP

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40
Q

What happens to cells undergoing apoptosis?

A

Cells shrunk and form lobes, which are eventually shed as membrane fragments

41
Q

Second messengers tend to be water soluble and small. This accounts for their ability to

A

Rapidly move throughout the cell by diffusion

42
Q

Why does testosterone not affect all cells in the body?

A

Only certain cells have cytoplasmic receptors for testosterone

43
Q

The process of phosphorylation is very important as a cellular mechanism for regulating protein activity. Phosphorylation does this by

A

Activating or inactivating proteins

44
Q

A small molecule that specifically binds to a larger molecule is called a

A

Ligand

45
Q

G protein linked receptors __, whereas receptor tyrosine kinases __

A

Are not enzymes

Have enzymatic function

46
Q

When a platelet contacts a damaged blood vessel, it is stimulated to release TA2. TA2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. In this example, TA2 is acting as a

A

Local regulator

47
Q

In many cases of local signaling

A

Messenger molecules are secreted by the signaling cell

48
Q

How does adenylyl cyclase help transmit signals within a cell?

A

It converts ATP to cAMP, which then broadcasts the signal to the rest of the cell

49
Q

A G protein is active when

A

GTP is bound to it

50
Q

In liver cells, epinephrine stimulates the breakdown of glycogen. As the signal transduction pathway progresses

A

The signal is amplified

51
Q

Cellular messaging

A

Cells can signal each other and interpret the signals they receive from other cells and the environment
Signals are most often chemicals
The same small set of cell signaling mechanisms shows up in diverse species and processes
Response is often phosphorylation

52
Q

In local signaling

A

Animal cells may communicate by direct contact
Animal and plant cells have cell junctions that directly connect the cytoplasm of adjacent cells
Signaling substances in the cytosine can pass freely between adjacent cells

53
Q

Synaptic

A

In long distance, plants and animals use chemicals — hormones
Hormonal signaling in animals is endocrine signaling

54
Q

Cells receiving signals go through 3 processes:

A

Reception
Transduction
Response

55
Q

In reception…

A

The target cell detects a signaling molecule that binds to a receptor protein on the cell surface

56
Q

In transduction…

A

The binding of the signaling molecule alters the pathway

57
Q

The binding between a signal molecule (ligand) and receptor is

A

Highly specific
A shape change in a receptor is often the initial transduction of the signal
Most signal receptors are plasma membrane proteins
Most water soluble signal molecules bind to specific sites on receptor proteins that span the plasma membrane

58
Q

3 types of membrane receptors

A 
GPCR
G protein coupled receptors
RTK
Receptor tyrosine kinases
Ion channel receptors 
(Ligand-gated ion channel)
59
Q

GPCRs are

A

Largest family
Cell surface transmembrane receptors that work with the help of a G protein
Phosphorylated
Energy rich GTP

60
Q

RTK

A

Membrane receptors
Attach phosphates to tyrosines
A receptor tyrosine kinase can trigger multiple signal transduction pathways at once

61
Q

A ligand-gated ion channel receptor acts

A

Like a gate when the receptor changes shape
When a signal molecule binds as a ligand to the receptor, the gate allows specific ions, such as Na+, Ca2+ through a channel in a receptor

62
Q

Intercellular receptors

A

Found in cytoplasm or nucleus of target cells

Small or hydrophobic chemical messengers can readily cross the membrane and activate receptors

63
Q

An activated hormone-receptor complex can act as

A

A transcription factor, turning on specific genes

64
Q

Transduction

A

Signal transduction usually involves multiple steps
Multi step pathways can greatly amplify a signal
Multistep pathways provide more opportunities for coordination and regulation of the cellular response

65
Q

Protein phosphorylation

A

Protein kinases transfer phosphates from ATP to protein — phosphorylation
Many relay molecules in signal transduction pathways are protein kinases, creating a phosphorylation cascade

66
Q

The cell’s response to an extracellular signal is called

A

The output response

67
Q

Response may occur

A

In cytoplasm or nucleus
Regulate the synthesis of enzymes or other proteins
Many pathways regulate the synthesis of enzymes or other proteins, usually by turning genes on/off in nucleus

68
Q

The final activated molecule in the signaling pathway may

A

Function as a transcription factor

69
Q

Signaling pathways can also affect the overall

A

Behavior of a cell

70
Q

Transcription factors control

A

Which genes are turned on, which genes are transcribed into mRNA

71
Q

Protein kinase

A

An enzyme that transfers phosphate groups from ATP to a protein

72
Q

RTK is a

A

Specific kind of protein kinase that phosphorylates tyrosines on the other receptor tyrosine kinase in a diner

73
Q

Phosphorylation cascade

A

Many relay molecules in signal transduction pathways are protein kinases, and they often act on other protein kinases in the pathway
Sometimes can decrease the activity of a protein

74
Q

Change in shape alters

A

Function of protein

75
Q

Protein phosphatases

A

Enzymes that can rapidly remove phosphate groups from proteins
Called dephosphorylation
Turns off the signal transduction pathway when initial signal is no longer present
Makes protein kinases available for reuse, enables cell to respond again to an extracellular signal

76
Q

Second messengers

A

Small
Non-protein
Water soluble molecules or ions
Readily spread throughout the cell by diffusion

77
Q

First messenger is considered

A

To be the extracellular signaling molecule

Ligand—binds to membrane receptor

78
Q

Binding of epinephrine to the plasma membrane of a liver cell elevates the cytosolic concentration of a compound called

A

Cyclic AMP

cAMP

79
Q

Adenylyl Cyclase

A

An enzyme embedded in the plasma membrane, converts ATP to cAMP in response to an external signal

80
Q

Protein kinase A

A

Activation of a serine/threonine kinase

81
Q

Because different kinds of cells turn on different sets of genes…

A

Different kinds of cells have different collections of proteins

82
Q

The response of a cell to a signal depends on

A

Its collection of signal receptor proteins, relay proteins, and proteins needed to carry out the response

83
Q

The efficiency of signal transduction is increased by the presence of

A

Scaffolding proteins

84
Q

Scaffolding proteins

A

Large relay molecules with several other relay proteins are attached

85
Q

The binding of signaling molecules to receptors is

A

Reversible

86
Q

Cells that are infected, damaged, or have reached the end of their functional life span often undergo

A

“Programmed cell death”

Apoptosis

87
Q

What happens during apoptosis?

A

The cell shrinks and becomes lobed

Cell’s parts are packed up in vesicles that are engulfed and digested by specialized scavenger cells, leaving no trace

88
Q

Different types of cells can respond differently to the same signaling molecule. What explains this apparent paradox?

A

Different types of cells possess different proteomes

89
Q

Early work on signal transduction and glycogen metabolism by Sutherland indicated that

A

The signal molecule did not interact directly with the cytosolic enzyme, but required an intact plasma membrane before the enzyme could be activated

90
Q

Steroid hormones can enter a cell by simple diffusion. Therefore steroids

A

Do not imitate cell signaling by interacting with a receptor in the plasma membrane

91
Q

Receptors for signal molecules

A

May be found embedded in the plasma membrane, or found within the cytoplasm or nucleus

92
Q

Testosterone does not affect all cells of the body because

A

Not all cells have cytoplasmic receptors for testosterone

93
Q

What event would activate a G protein?

A

Replacement of GDP with GTP

94
Q

The cellular response of a signal pathway that terminates at a transcription factor would be

A

The synthesis of mRNA

95
Q

Phosphorylation can

A

Either activate or inactivate a protein

96
Q

The source of phosphate for a phosphorylation cascade is

A

ATP

97
Q

What is not a potential source of Ca2+ that can be released into the cytoplasm?

A

Lysosomes

98
Q

Signal transduction pathway

A

Sequence of changes in a series of different molecules

Biology (16 decks)

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