Chapter 11 Flashcards
(148 cards)
1
Q
What is the primary method of communication between cells in a multicellular organism?
A
Signaling molecules
Cells use signaling molecules to communicate with each other in various processes.
2
Q
What is local signaling?
A
Communication between animal cells by direct contact
Local signaling allows for immediate and direct communication between adjacent cells.
3
Q
What structures connect the cytoplasm of adjacent animal and plant cells?
A
Cell junctions
Cell junctions facilitate the direct passage of signaling substances between cells.
4
Q
What can pass between adjacent cells in local signaling?
A
Signaling substances in the cytosol
This allows for rapid communication and response between neighboring cells.
5
Q
Why is local signaling important during embryonic development?
A
It helps in cell communication necessary for proper development
Local signaling plays a crucial role in guiding the growth and differentiation of cells during embryogenesis.
6
Q
What role does local signaling play in the immune response?
A
It facilitates communication between immune cells
Local signaling is vital for coordinating the actions of immune cells in response to pathogens.
7
Q
How does local signaling contribute to maintaining adult stem cell populations?
A
It regulates the communication necessary for stem cell maintenance
Local signaling is essential for the balance between stem cell renewal and differentiation.
8
Q
What structures do plasma membranes and cell walls use for local signaling?
A
Gap junctions or plasmodesmata
Gap junctions are found between animal cells, while plasmodesmata are found between plant cells.
9
Q
What is the function of gap junctions?
A
They facilitate communication between animal cells
Gap junctions allow for direct transfer of ions and small molecules.
10
Q
What do plasmodesmata do?
A
They facilitate communication between plant cells
Plasmodesmata are channels that traverse the cell walls of plant cells.
11
Q
What type of signaling in animals is called paracrine signaling?
A
Local signaling using secreted messenger molecules that travel short distances
Paracrine signaling is crucial for local communication between cells.
12
Q
What are growth factors?
A
Local regulators that stimulate nearby target cells to grow and divide
Growth factors play a significant role in cell signaling and tissue repair.
13
Q
What occurs during synaptic signaling?
A
A neurotransmitter is released in response to an electric signal
Synaptic signaling is essential for communication in the nervous system.
14
Q
True or False: Drugs used to treat depression affect synaptic signaling.
A
True
These drugs can influence neurotransmitter levels and signaling processes.
15
Q
What molecules do plants and animals use for long-distance signaling?
A
Hormones
Hormones are chemical messengers that travel through the circulatory system to target cells.
16
Q
What is the process called when specialized cells release hormones in animals?
A
Hormonal (or endocrine) signaling
This process involves the release of hormones into the bloodstream.
17
Q
What determines a cell’s ability to respond to a signal?
A
Presence of a specific receptor for that signal
Only cells with the appropriate receptors can respond to particular hormones.
18
Q
What type of signaling involves messenger molecules and target cells nearby?
A
Paracrine signaling
This type of local signaling allows for communication between nearby cells.
19
Q
What triggers the release of neurotransmitters in synaptic signaling?
A
Electrical signal
An electrical impulse in the neuron leads to the release of neurotransmitters across a synapse.
20
Q
In synaptic signaling, what diffuses across the synapse?
A
Neurotransmitter
Neurotransmitters are chemical messengers that transmit signals between neurons.
21
Q
Fill in the blank: In animals, specialized cells release hormones which travel to _______ via the circulatory system.
A
target cells
22
Q
What is long-distance signaling?
A
A type of signaling where hormones travel through the bloodstream to target cells.
23
Q
What is an endocrine cell?
A
A cell that secretes hormones into the bloodstream.
24
Q
What is a target cell?
A
A cell that specifically binds to a hormone.
25
What are the three stages of cell signaling?
Signal Reception, Signal Transduction, Cellular Response.
26
Who discovered how the hormone epinephrine acts on cells?
Earl W. Sutherland and colleagues.
27
Fill in the blank: Hormone binds to a _______.
[target cell]
28
What travels in the bloodstream?
Hormone.
29
What is the role of signaling molecules in cell signaling?
They facilitate communication between cells.
30
What are relay molecules?
Molecules that help transmit the signal within the cell.
31
What is the cellular response in cell signaling?
The outcome or effect that occurs after the signal is processed.
32
True or False: Only endocrine cells can secrete hormones.
True.
33
What is the significance of Sutherland's work?
It highlighted the processes through which cells receive and respond to signals.
34
Fill in the blank: Cells receiving signals go through three processes: Signal Reception, Signal Transduction, and _______.
[Cellular Response]
35
What does the term 'secrete' refer to in cellular contexts?
When a molecule releases from cells.
36
What is the relationship between blood vessels and hormones?
Hormones travel through blood vessels to reach target cells.
37
What occurs during the reception of a signaling molecule?
A signaling molecule binds to a receptor protein, causing it to change shape
## Footnote
This process initiates signal transduction.
38
What is the relationship between a ligand and a signal molecule?
A ligand is the same thing as a signal molecule and messenger molecule
## Footnote
Ligands are crucial for cellular communication.
39
What is typically the first step in signal transduction?
A shape change in a receptor
## Footnote
This change is triggered by the binding of a signaling molecule.
40
Where are most signal receptors located?
Most signal receptors are plasma membrane proteins
## Footnote
Some receptors are also located inside the cell.
41
What are G protein-coupled receptors (GPCRs)?
The largest family of cell-surface receptors
## Footnote
GPCRs play a key role in transmitting signals from outside the cell.
42
What type of molecules typically bind to receptor proteins on the plasma membrane?
Most water-soluble signal molecules
## Footnote
These molecules transmit information from the extracellular environment to inside the cell.
43
What are the three main types of membrane receptors?
* G protein-coupled receptors
* Receptor tyrosine kinases
* Ion channel receptors
## Footnote
These receptors play crucial roles in cell signaling and communication.
44
What are G protein-coupled receptors (GPCRs)?
Cell-surface transmembrane receptors that work with the help of a G protein
## Footnote
GPCRs are involved in various physiological processes and are targets for many pharmaceuticals.
45
What do G proteins bind to in their function?
Energy-rich GTP
## Footnote
GTP binding is essential for G protein activation and subsequent signaling pathways.
46
What is a key structural characteristic of G proteins?
G proteins are all very similar in structure
## Footnote
This structural similarity allows for consistent functionality across different types of G proteins.
47
How widespread and diverse are GPCR systems?
Extremely widespread and diverse in their functions
## Footnote
GPCRs are involved in numerous signaling pathways and biological processes.
48
Fill in the blank: G protein-coupled receptors work with the help of a _______.
G protein
## Footnote
This interaction is critical for transmitting signals from outside the cell to the inside.
49
What are receptor tyrosine kinases (RTKs)?
Membrane receptors that catalyze the transfer of phosphate groups from ATP to another protein.
50
What can a receptor tyrosine kinase trigger?
Multiple signal transduction pathways at once.
51
What is associated with abnormal functioning of RTKs?
Many types of cancers.
52
What is a ligand-gated ion channel receptor?
A receptor that opens and closes in response to a signal molecule binding as a ligand
53
What happens when a ligand binds to a ligand-gated ion channel receptor?
It allows specific ions, such as Na+ or Ca2+, to pass through a channel in the receptor
54
Where are intracellular receptor proteins located?
In the cytoplasm or nucleus of target cells
55
What type of chemical messengers can readily cross the membrane and activate intracellular receptors?
Small or hydrophobic chemical messengers
56
Give two examples of hydrophobic messengers.
* Steroid hormones
* Thyroid hormones
57
What can an activated hormone-receptor complex act as?
A transcription factor
58
What is the role of a transcription factor in gene expression?
It turns on or off specific genes
59
Fill in the blank: An activated hormone-receptor complex can express the gene, whatever _______ are in the gene.
[proteins]
60
What is the main concept of transduction in cell signaling?
Cascades of molecular interactions transmit signals from receptors to relay molecules in the cell
## Footnote
This involves a series of steps that amplify the signal and regulate the cellular response.
61
What is a characteristic of multistep pathways in cell signaling?
They can greatly amplify a signal
## Footnote
This amplification allows for a more robust cellular response to stimuli.
62
What opportunities do multistep pathways provide in cellular response?
More opportunities for coordination and regulation
## Footnote
This ensures that the cellular response is appropriate and timely.
63
What triggers the first step in a signal transduction pathway?
The binding of a signaling molecule to a receptor
## Footnote
This initial binding is crucial for the cascade of interactions that follows.
64
What happens after the activated receptor in a signal transduction pathway?
It activates another protein, which activates another, and so on
## Footnote
This sequential activation continues until the final protein producing the response is activated.
65
How is the signal transduced at each step of the pathway?
Into a different form, commonly a shape change in a protein
## Footnote
This change is often essential for the function of the protein involved.
66
What is the process called when phosphates are transferred from ATP to proteins?
Phosphorylation
## Footnote
Phosphorylation is a key mechanism for regulating protein activity in cells.
67
What is the role of protein kinases in signal transduction pathways?
They create a phosphorylation cascade
## Footnote
Protein kinases are relay molecules that activate a series of downstream proteins.
68
What process removes phosphates from proteins?
Dephosphorylation
## Footnote
Dephosphorylation is performed by enzymes known as protein phosphatases.
69
What acts as a molecular switch in regulating protein activity?
Phosphorylation and dephosphorylation system
## Footnote
This system can turn activities on and off, or modulate their intensity.
70
True or False: Protein phosphatases add phosphates to proteins.
False
## Footnote
Protein phosphatases are responsible for removing phosphates, not adding them.
71
Fill in the blank: The enzyme that catalyzes dephosphorylation is called _______.
protein phosphatase
## Footnote
Protein phosphatases play a crucial role in reversing phosphorylation.
72
What is a common outcome of phosphorylation and dephosphorylation in cellular processes?
Regulation of protein activity
## Footnote
These processes are essential for controlling various cellular functions.
73
What type of molecules are often involved in phosphorylation cascades?
Relay molecules
## Footnote
Relay molecules, especially protein kinases, amplify signals in cellular communication.
74
What are second messengers?
Small, nonprotein, water-soluble molecules or ions that spread throughout a cell by diffusion
## Footnote
They participate in signaling pathways initiated by GPCRs and RTKs.
75
Which molecules are examples of second messengers?
* Cyclic AMP
* Calcium ions
* cGMP
* DAG
* Phosphoinositides
## Footnote
Cyclic AMP is one of the most widely used second messengers.
76
What is cyclic AMP (cAMP)?
A small molecule produced from ATP and one of the most widely used second messengers
## Footnote
It is involved in various signaling pathways.
77
What enzyme converts ATP to cAMP?
Adenylyl cyclase
## Footnote
This conversion occurs in response to an extracellular signal.
78
What is the role of adenylyl cyclase?
Converts ATP to cAMP in the plasma membrane
## Footnote
It acts in response to extracellular signals.
79
Fill in the blank: Cyclic AMP is produced from _______.
ATP
80
True or False: Second messengers are typically large, protein-based molecules.
False
81
What does phosphodiesterase do in the context of cAMP?
Hydrolyzes cAMP to AMP
## Footnote
This action terminates the signaling initiated by cAMP.
82
What is the significance of calcium ions as second messengers?
They play a crucial role in various cellular signaling processes
## Footnote
Calcium ions can trigger muscle contraction, neurotransmitter release, and other important functions.
83
What triggers the formation of cAMP?
Many signal molecules
## Footnote
Signal molecules are often hormones or neurotransmitters that initiate signaling cascades.
84
Which components are involved in cAMP pathways?
G proteins, G protein-coupled receptors, and protein kinases
## Footnote
These components work together to transduce signals from outside the cell to elicit cellular responses.
85
What is the primary function of protein kinase A in relation to cAMP?
Phosphorylates various other proteins
## Footnote
This phosphorylation can activate or deactivate target proteins, thus regulating various cellular functions.
86
How do G protein systems further regulate cell metabolism?
By inhibiting adenylyl cyclase
## Footnote
This inhibition decreases the levels of cAMP in the cell, thus affecting the signaling pathways.
87
What is the role of the first messenger in GPCR signaling?
It is a signaling molecule such as epinephrine
## Footnote
The first messenger binds to the GPCR to initiate the signaling cascade.
88
What is the second messenger in the GPCR signaling pathway?
cAMP
## Footnote
cAMP acts as a secondary signal that propagates the signal within the cell.
89
What cellular responses are triggered by protein kinase A activation?
Varied cellular responses depending on the proteins phosphorylated
## Footnote
These responses can include changes in metabolism, gene expression, and cell function.
90
How does the cholera bacterium, Vibrio cholerae, affect cAMP levels?
Produces a toxin that modifies a G protein to be stuck in its active form
## Footnote
This modification leads to continuous production of cAMP.
91
What is the consequence of increased cAMP production in intestinal cells?
Secretion of large amounts of salt into the intestines
## Footnote
This salt secretion leads to osmotic water loss, causing severe dehydration.
92
True or False: An untreated person with cholera can die from loss of water and salt.
True
## Footnote
The rapid loss of fluids and electrolytes can lead to death if not treated promptly.
93
What are calcium ions used for in cellular signaling?
Calcium ions (Ca²⁺) are used widely as a second messenger, even more so than cAMP.
## Footnote
Calcium ions play a critical role in various cellular processes by transmitting signals within cells.
94
Why can calcium ions function as a second messenger?
Calcium ions can function as a second messenger because their concentration in the cytosol is normally much lower than the concentration outside the cell.
## Footnote
This difference in concentration allows small changes in the number of calcium ions to represent a relatively large percentage change in calcium concentration.
95
What happens when there is a small change in the number of calcium ions?
A small change in number of calcium ions represents a relatively large percentage change in calcium concentration.
## Footnote
This property makes calcium ions highly effective as signaling molecules.
96
What triggers an increase in calcium in the cytosol?
A signal relayed by a signal transduction pathway may trigger an increase in calcium in the cytosol.
## Footnote
This increase is crucial for various cellular responses.
97
What are the additional second messengers involved in calcium release pathways?
Inositol triphosphate (IP3) and diacylglycerol (DAG) are additional second messengers involved in calcium release pathways.
## Footnote
These second messengers are produced by the cleavage of a certain kind of phospholipid in the plasma membrane.
98
Fill in the blank: Calcium ions are produced by _______ in the cytosol.
signal transduction pathways
99
True or False: Calcium ions have a higher concentration inside the cell than outside.
False
100
What is the role of inositol triphosphate (IP3) in calcium signaling?
Inositol triphosphate (IP3) is involved in signaling pathways that lead to the release of calcium from intracellular stores.
## Footnote
IP3 is generated from phospholipid cleavage in the plasma membrane and plays a key role in cellular signaling.
101
What are calcium ions used for in cellular signaling?
Calcium ions (Ca²⁺) are used widely as a second messenger, even more so than cAMP.
## Footnote
Calcium ions play a critical role in various cellular processes by transmitting signals within cells.
102
Why can calcium ions function as a second messenger?
Calcium ions can function as a second messenger because their concentration in the cytosol is normally much lower than the concentration outside the cell.
## Footnote
This difference in concentration allows small changes in the number of calcium ions to represent a relatively large percentage change in calcium concentration.
103
What happens when there is a small change in the number of calcium ions?
A small change in number of calcium ions represents a relatively large percentage change in calcium concentration.
## Footnote
This property makes calcium ions highly effective as signaling molecules.
104
What triggers an increase in calcium in the cytosol?
A signal relayed by a signal transduction pathway may trigger an increase in calcium in the cytosol.
## Footnote
This increase is crucial for various cellular responses.
105
What are the additional second messengers involved in calcium release pathways?
Inositol triphosphate (IP3) and diacylglycerol (DAG) are additional second messengers involved in calcium release pathways.
## Footnote
These second messengers are produced by the cleavage of a certain kind of phospholipid in the plasma membrane.
106
Fill in the blank: Calcium ions are produced by _______ in the cytosol.
signal transduction pathways
107
True or False: Calcium ions have a higher concentration inside the cell than outside.
False
108
What is the role of inositol triphosphate (IP3) in calcium signaling?
Inositol triphosphate (IP3) is involved in signaling pathways that lead to the release of calcium from intracellular stores.
## Footnote
IP3 is generated from phospholipid cleavage in the plasma membrane and plays a key role in cellular signaling.
109
What is the cell's response to an extracellular signal called?
Output response
## Footnote
The output response is the result of cell signaling pathways activated by extracellular signals.
110
What are the two main types of activities regulated by cellular responses?
Transcription and cytoplasmic activities
## Footnote
These activities are essential for the cell to adapt and respond to changes in its environment.
111
What is the role of signaling pathways in cells?
They route the response of enzymes or other proteins by turning genes on or off in the nucleus.
## Footnote
This process is essential for regulating cellular functions and responses.
112
What is a transcription factor?
The final activated molecule in the signaling pathway that may function to regulate gene expression.
## Footnote
Transcription factors bind to specific DNA sequences to control the transcription of genetic information.
113
What happens when epinephrine binds to a G protein-coupled receptor?
It initiates a signaling cascade that leads to cellular responses.
## Footnote
This binding activates the G protein and subsequently affects downstream signaling molecules.
114
Fill in the blank: The binding of epinephrine leads to the activation of _______.
G protein
## Footnote
G proteins are molecular switches that relay signals from receptors to target molecules inside the cell.
115
What is the initial effect of an active G protein?
It activates adenylyl cyclase.
## Footnote
Adenylyl cyclase converts ATP to cyclic AMP, which is a secondary messenger in the signaling pathway.
116
How many molecules of cyclic AMP are produced from one active adenylyl cyclase?
10^4 molecules.
## Footnote
Cyclic AMP amplifies the signal within the cell, leading to further downstream effects.
117
What activates protein kinase A?
Cyclic AMP.
## Footnote
Protein kinase A plays a critical role in the signaling pathways by phosphorylating various target proteins.
118
What is the function of phosphorylase kinase?
It activates glycogen phosphorylase.
## Footnote
Glycogen phosphorylase is responsible for breaking down glycogen into glucose-1-phosphate.
119
True or False: The signaling pathway results in the conversion of glycogen to glucose-1-phosphate.
True
## Footnote
This conversion is essential for providing energy to the cell during stress or increased demand.
120
List the order of activation in the signaling pathway starting from epinephrine.
* Epinephrine binds to G protein-coupled receptor
* Active G protein
* Active adenylyl cyclase
* Cyclic AMP
* Active protein kinase A
* Active phosphorylase kinase
* Active glycogen phosphorylase
## Footnote
This sequence illustrates the amplification of the signal and the resulting cellular response.
121
What do signal receptors, relay molecules, and second messengers participate in?
A variety of pathways leading to nuclear and cytoplasmic responses, including cell division
## Footnote
These pathways are essential for cellular communication and coordination.
122
What is the first aspect of signal regulation?
Amplification of the signal (and thus the response)
## Footnote
This allows a small initial signal to produce a large cellular response.
123
What is the second aspect of signal regulation?
Specificity of the response
## Footnote
This ensures that the correct response is activated for each specific signal.
124
What is the third aspect of signal regulation?
Overall efficiency of response, enhanced by scaffolding proteins
## Footnote
Scaffolding proteins help organize signaling components to improve efficiency.
125
What is the fourth aspect of signal regulation?
Termination of the signal
## Footnote
This prevents continuous activation of the signaling pathway when it is no longer needed.
126
What role do enzyme cascades play in signal amplification?
They amplify the cell's response to the signal
## Footnote
Each step in the cascade can produce a greater number of activated products.
127
Fill in the blank: At each step of an enzyme cascade, the number of activated products can be much greater than in the preceding step, demonstrating _______.
signal amplification
128
What allows different kinds of cells to detect and respond to different signals?
Different collections of proteins
## Footnote
Each type of cell has a unique set of proteins that determine its signaling capabilities.
129
What can cause the same signal to have different effects in different cells?
Different proteins and pathways
## Footnote
Variations in protein expression and signaling pathways lead to diverse cellular responses.
130
What mechanisms help a cell coordinate incoming signals?
Pathway branching and 'cross-talk'
## Footnote
These mechanisms allow for integration and regulation of multiple signaling pathways.
131
What are scaffolding proteins?
Large relay proteins to which several other relay proteins are attached
## Footnote
Scaffolding proteins act as platforms for organizing signaling complexes, enhancing efficiency.
132
How do scaffolding proteins increase signal transduction efficiency?
By grouping together different proteins involved in the same pathway
## Footnote
This organization minimizes the distance and time required for signal transmission.
133
In addition to grouping proteins, what else can scaffolding proteins do?
Help activate some of the relay proteins
## Footnote
Scaffolding proteins may play a role in the activation process of signaling components.
134
Fill in the blank: The same signal can have different effects in cells with different _______.
proteins and pathways
## Footnote
This diversity in cellular responses is crucial for complex biological functions.
135
What is an essential aspect of cell signaling?
Inactivation mechanisms
## Footnote
Inactivation mechanisms play a crucial role in regulating cell signaling by ensuring that signaling pathways are not perpetually active.
136
What happens when the concentration of external signaling molecules falls?
Fewer receptors will be bound
## Footnote
This change leads to unbound receptors reverting to an inactive state, thus stopping the signaling process.
137
What is apoptosis?
The best-understood type of programmed cell death
## Footnote
Apoptosis is a controlled process where cells undergo death in response to infection, damage, or reaching the end of their functional lives.
138
What occurs to components of the cell during apoptosis?
They are chopped up and packaged into vesicles
## Footnote
These vesicles are then digested by scavenger cells, preventing harm to neighboring cells.
139
What is a benefit of apoptosis?
Prevents enzymes from leaking out of a dying cell
## Footnote
This mechanism protects surrounding cells from potential damage caused by these enzymes.
140
Apoptosis requires integration of what?
Multiple cell-signaling pathways
## Footnote
This integration ensures that the decision to undergo apoptosis is well-coordinated and appropriate for the cell's context.
141
What is apoptosis?
A process of programmed cell death
## Footnote
Apoptosis is a crucial mechanism in maintaining cellular homeostasis and development.
142
What are the two types of death signals in apoptosis?
* No death signal
* Death signal
143
What are the three main steps in cell signaling?
* Signal reception
* Signal transduction
* Cellular response
144
What is the role of a receptor in cell signaling?
Activation of cellular response
145
What do relay molecules do in cell signaling?
They transmit signals within the cell
146
Fill in the blank: Signaling between cells can be either _______ or long distance.
local
147
True or False: Apoptosis is an inactive process.
False
148
What is a signaling molecule?
A molecule that initiates a signaling cascade in cells
