1 - Interpreting Extracellular Signals & Signal Transduction Flashcards

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1
Q

What does signal transduction involve (two basic components)?

A

A signal in, and a signal out

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2
Q

For signal transduction, what is the most common and general kind of input signal?

A

Extracellular signaling molecule

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3
Q

For signal transduction, what is the most common and general kind of output signal?

A

Intracellular signaling molecule

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4
Q

What questions are involved in signal transduction (in terms of the signals) (4 general questions)?

A
  1. How are signals generated and released?
  2. How are signals perceived by the recipient?
  3. How is the response to the signal generated?
  4. How are multiple signals integrated?
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5
Q

What questions are involved in chemical messengers (3 general questions)?

A
  1. How does it mediate a response in a particular cell type?
  2. How does it mediate pleiotropic responses? (different effects by same chemical messenger)
  3. How does it mediate different responses in different targets?
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6
Q

How can chemical messengers be regulated (general mechanisms)?

A

Synthesis, packaging, secretion, and degradation

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7
Q

Why is cell signaling important?

A

Controls almost every aspect of cell structure and function, need to respond to environment, etc.

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8
Q

What processes does cell signaling regulate?

A

Growth and division

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9
Q

What field of biology was useful for studying cell signaling?

A

Virology

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10
Q

Why is virology useful for studying cell signaling?

A

Viruses need to infect cells to function, so by studying viruses, we learned about the basics of cells

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11
Q

What are some examples of extracellular signals?

A

Hormones, pheromones, heat, cold, light, osmotic pressure, concentration changes of glucose, K+, Ca2+, cAMP

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12
Q

What are some examples of intracellular signals?

A

Modification of metabolism, production and degradation of substances, phosphorylation, activation and inhibition of reactions

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13
Q

What are the 5 general principles of cell signaling?

A
  1. Signals act over different ranges
  2. Signals have different chemical natures
  3. The same signal can induce a different response in different cells
  4. Cells respond to sets of signals
  5. Receptors relay signals via intracellular signaling cascades
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14
Q

What does it mean that signals act over different ranges?

A

Different spatial capabilities of the signals (local vs endocrine, etc.)

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15
Q

What does it mean that signals have different chemical natures?

A

Different structures of the different signals lead to different functions

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16
Q

How can the same signal induce a different response in different cells?

A

Different receptors and relay cascades (found in different cells) can cause a different output based on a signaling input

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17
Q

What does it mean that cells respond to sets of signals?

A

The cell integrates multiple signals over space and time to produce a particular response

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18
Q

What is the advantage of relaying signals via intracellular signaling cascades?

A

More amplification, which allows for a large response from a small amount of signaling molecule

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19
Q

What do sensors do?

A

Detect the external signals in the environment

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20
Q

What do the internal logic circuits do?

A

Responds to the inputs, and decided what is the proper response

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21
Q

What do actuators do?

A

The final step in the pathway to produce a response (cell movement, growth, chemicals, etc.)

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22
Q

Why is timing important in cell signaling?

A

Different responses could need a fast or slow response, a sustained response, or a degrading response. Thus, the timing is important based on the stimulus

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23
Q

What is the time scale of altering protein function?

A

Fast (sec to min)

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24
Q

What is the time scale of altering gene expression?

A

Slow (min to hour)

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25
Q

Why is altering protein function fast?

A

Proteins are already in the cytoplasm to be modified

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26
Q

Why is altering gene expression slow?

A

Need all the machinery to create new proteins and alter protein levels

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27
Q

What is the range of endocrine signaling?

A

Long range (through bloodstream)

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28
Q

What is the range of paracrine signaling?

A

Local (close neighbors)

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29
Q

What is the range of neuronal or synaptic signaling?

A

Synapse of two neurons or other cells

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30
Q

What is the range of cell-cell recognition?

A

Direct contact

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31
Q

What are some examples of endocrine signaling molecules?

A

Estrogen, epinepherin

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32
Q

What are some examples of paracrine signaling molecules?

A

Nitric oxide, histamines, prostaglandins

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33
Q

What are some examples of neuronal signaling molecules?

A

Neurotransmitters (GABA, dopamine, etc.)

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34
Q

What are some examples of cell-cell recognition signaling molecules?

A

Delta/notch

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35
Q

What is autocrine signaling?

A

A cell releases a signal, which can bind to its own receptors and cause a response

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36
Q

What does acetylcholine do to heart pacemakers cells?

A

Decreases rate of firing

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37
Q

What does acetylcholine do to salivary gland cells?

A

Secretion of chemicals in vesicles

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38
Q

What does acetylcholine do to skeletal muscle cells?

A

Contraction

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39
Q

How can acetylcholine lead to different responses in heart, salivary, and skeletal muscle cells?

A

Different detection (receptors) and intracellular cascades (downstream signals) lead to different responses

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40
Q

What are some examples of classes of extracellular signals?

A

Small molecules, gases, steroids, eicosanoids, peptides

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41
Q

What are some examples of receptor types?

A

G-protein coupled receptors (GPCRs), receptor protein-tyrosine kinases (RTKs), ligand gated channels, steroid hormone receptors, specific receptors (B and T cell receptors)

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42
Q

What are some examples of small molecules as extracellular signals?

A

Amino acids and their derivatives, such as acetylcholine, epinepherine, and dopamine

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43
Q

What are some examples of gases as extracellular signals?

A

Nitric oxide (NO) and carbon monoxide (CO)

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44
Q

What do steroids regulate?

A

Sexual differentiation, pregnancy, carbohydrate metabolism

45
Q

What are eicosanoids?

A

Lipids derived from fatty acids (extracellular signal)

46
Q

What are the 4 properties of signaling molecules?

A

Specificity, amplification, adaptation/desensitization, and integration

47
Q

What is meant by specificity (for signaling molecules)?

A

A signaling molecule fits into one binding site, and other signals do not fit

48
Q

What is meant by amplification (for signaling molecules)?

A

Enzymes can affect multiple copies of other enzymes, which causes a geometric increase of affected molecules

49
Q

What is meant by adaptation or desensitization (for signaling molecules)?

A

Make the receptor no longer respond to the signal

50
Q

What is the advantage of adaptation/desensitization?

A

Feedback to the system, make sure it can be turned off

51
Q

What is meant by integration (for signaling molecules)?

A

The cell can combine multiple inputs to lead to an appropriate response

52
Q

What is a molecular signaling device?

A

A molecular change leads to a molecular response

53
Q

What is a network signaling device?

A

Multiple proteins interact based on a signal to generate a response

54
Q

What is a cellular signaling device?

A

The entire cells receives signals, and generated an overall cellular response

55
Q

What is the different between a molecular, network, and cellular signaling device?

A

Size and scope of the signaling

56
Q

What is the purpose of a receptor?

A

Relay information about the extracellular environment to the intercellular environment

57
Q

What are effector proteins?

A

Proteins that mediate the appropriate response (last step in the cascade)

58
Q

How stable is cell signaling (response)?

A

Transient changes (min to hours)

59
Q

How stable is gene expression (response)?

A

Stable (hours to years)

60
Q

What is the energetic cost of cell signaling (compared to gene expression)?

A

Energetically cheaper

61
Q

What is the energetic cost of gene expression?

A

Energetically expensive

62
Q

Why is gene expression more energetically costly than cell signaling?

A

Needs transcription and translation machinery

63
Q

Why is cell signaling less energetically costly than gene expression?

A

Not changing protein synthesis / expression

64
Q

What are the 4 ways that proteins in cells can respond to signals?

A

Binding/dissociation, post-translational modification, conformational change, and localization

65
Q

What is binding/dissociation?

A

Two molecules coming together / apart

66
Q

What is conformational change?

A

Change in the structure of a protein or other molecule

67
Q

What is a post-translational modification?

A

Add another molecule to the outside of a first molecule to change its function

68
Q

What is localization?

A

One molecules moves to a different part of the cell, thus changing the signal pathway

69
Q

How does amplification work?

A

A protein activates multiple copies of the next component in the pathway

70
Q

Why are signaling cascades used for amplification?

A

Allows for multiple steps, which can be amplified

71
Q

What is the importance of amplification?

A

A single molecular event can lead to 1,000,000 active control factors

72
Q

What is bacterial chemotaxis?

A

Movement based on a chemical

73
Q

What would a bacterium do if there was no stimulant present?

A

Move in a random walk

74
Q

What would a bacterium do if there was a positive stimulant present?

A

Move towards the stimulant

75
Q

What would a bacterium do if there was a negative stimulant present?

A

Move away from the stimulant

76
Q

How do bacteria move?

A

Run and tumble motif

77
Q

How do multicellular organisms use signal transduction?

A

Senses

78
Q

What is meant by “structural heterogeneity of signaling molecules”?

A

Lots of different shapes of signaling molecules

79
Q

What is the significance of “structural heterogeneity of signaling molecules”

A

Specificity towards one of many different kinds of receptors

80
Q

What are the 5 types of chemical messengers?

A

Neurotransmitters, hormones, growth factors, cytokines, and growth hormones

81
Q

How are chemical messengers regulated?

A

Synthesis, packaging, secretion, and degradation

82
Q

What are neurotransmitters?

A

Chemical messengers found in the clefts of neurons

83
Q

What type of signaling is neurotransmitters primarily used in?

A

Neuronal/synaptic signaling

84
Q

What are cytokines?

A

Cell to cell signaling molecules that change gene activation or cellular function

85
Q

What type of signaling is cytokines primarily used in?

A

Paracrine signaling

86
Q

What are some stimuli that can induce cytokine expression?

A

Hypoxia, injury, seizures, inflammation, infection

87
Q

True or false: cytokines are always advantageous

A

False: sometimes cytokines can protect, sometimes cytokines can cause damage

88
Q

What are hormones?

A

Chemicals released into blood to different tissues

89
Q

Where are hormones produced?

A

Glands

90
Q

What type of signaling is hormones primarily used in?

A

Endocrine signaling

91
Q

What is a growth factor?

A

A signaling molecule that directs growth

92
Q

What process is growth factors important for?

A

Development (layers, axes, etc.)

93
Q

What are growth hormones?

A

Hormones that are associated with growth

94
Q

How is a class of chemical messenger determines (ex: neurotransmitter vs hormone)

A

What their target is, and how they’re moved around

95
Q

Where are microtubules anchored?

A

At the centrosome

96
Q

What signaling would homeostasis use?

A

Long term (maintain a constant state)

97
Q

Why is autocrine signaling useful?

A

Use its own signal from an initial input to generate new receptors for a next expected input

98
Q

What is an example of autocrine signaling?

A

Immune system, extracellular matrix signaling (make ECM, which binds to receptor that responds to ECM that was made, making it move on to another phase), etc.

99
Q

What is self-identity?

A

The cell knows what kind of cell it is

100
Q

What signaling is used for self-identity?

A

Autocrine signaling

101
Q

How do cancer cells use autocrine signaling?

A

Avoid cell cycle block (continuous division)

102
Q

What is upstream signaling?

A

The cell that sends the signal would have an impact (response) based on the reception of the signal

103
Q

What is downstream signaling?

A

The cell that receives the signal would have an impact (response) based on the reception of the signal

104
Q

How is evolution involved in cell signaling?

A

Create specific and fast signaling that is useful

105
Q

What does DREADD stand for?

A

Designer Receptors Exclusively Activated by Designer Drugs

106
Q

What do DREADDs do?

A

Synthetic GPCR that responds only to synthetic molecules

107
Q

How can drugs take advantage of signaling pathways to solve a problem?

A

Drugs can turn down bad pathways, or turn up good pathways

108
Q

Is cell signaling hereditary?

A

Yes. It can be passed down and selected upon