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Physl > Cell Physiology - Topic 3 Slides > Flashcards

Cell Physiology - Topic 3 Slides Flashcards

1
Q

What are the two types of Intracellular communication?

A

Direct and Indirect

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2
Q

What is the Direct cell communication mechanism?

A

Gap Junctions

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3
Q

What is the Indirect cell communication mechanism?

A

Chemical messengers

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4
Q

What are the two types of chemical messengers?

A

Lipid soluble and lipid insoluble

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5
Q

What is Signal transduction?

A

The sequence of events between binding of messenger to receptor and the production of a cellular response

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6
Q

What are the Properties of Receptors?

A
  • Specificity
  • Saturation
  • Affinity
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7
Q

Where are the two places Receptors can be?

A
  • In the plasma membrane (transmembrane)

* Intracellular (cytosolic, nuclear)

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8
Q

What type of messengers do Intracellular membranes bind to?

A

Lipid soluble messengers like steroid hormones

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9
Q

Where do Intracellular receptors bind to receptors?

A

In the Cytoplasm or Nucelus

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10
Q

How do Intracellular receptors alter the transcription of mRNA?

A

By binding to the Response Element

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11
Q

What is the Response Element?

A

A specific sequence of DNA near the beginning of a gene that alters the rate of protein synthesis

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12
Q

What are Gap Junctions?

A

When transmembrane proteins form channels linking one cell to another

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13
Q

What do gap junctions allow for?

A

Ions and small molecules to move from one cell to another

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14
Q

What is Signal Transduction?

A

The sequence of events between the binding of messenger to its receptor and the production of the cellular response

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15
Q

Why don’t chemical messengers affect all cells?

A

Because they can only affect cells that have receptors to the messenger

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16
Q

How might the binding of a chemical receptor to two different messengers affect the response?

A

There will be two different cell responses depending on which receptor is bound to

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17
Q

Where will a chemical messenger bind if it is hydrophilic or lipid insoluble?

A

Receptors in the plasma membrane

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18
Q

What do water soluble chemical messengers bind to?

A

Receptors on the extracellular surface of the plasma membrane

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19
Q

What are some examples of water soluble chemical messengers?

A

Hormones, neurotransmitters, paracrine/autocrine compounds

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20
Q

What are membrane bone receptors usually linked to?

A
  • A Channel
  • An enzyme
  • G-protein-linked receptors
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21
Q

What is the First Messenger?

A

Extracellular chemical messenger that binds to a specific membrane receptor

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22
Q

What is the Second Messenger?

A

Substance that enter or are generated in the cytoplasm of a cell in response to the binding of an extracellular messenger (first messenger) to receptor

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23
Q

What is Protein Kinase?

A

An enzyme that phosphorylates another protein

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24
Q

Where are G-proteins found?

A

The systolic surface of the plasma membrane

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25
Q

What do G proteins bind to?

A

Guanosine nucleotides (GDP and GTP)

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26
Q

What are the 3 subunits of G proteins?

A

α, β, γ

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27
Q

What does the alpha subunit of G protein bind to?

A

Guanosine nucleotides

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28
Q

What is the inactive form of G proteins?

A

G-GDP

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29
Q

What is the active form of G proteins?

A

G-GTP

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30
Q

What are the 3 types of G Proteins?

A
  • Affect ion channels
  • Stimulatory G proteins
  • Inhibitory G proteins
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31
Q

What do G proteins that affect ion channels do?

A

Open or close channles

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32
Q

What do stimulatory G proteins do?

A

Activate enzymes

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33
Q

What do Inhibitory G proteins do?

A

Inhibit enzymes

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34
Q

What are Paracrine compounds?

A

Compounds released by one cell which act on neighboring cells near its secretion

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35
Q

What are Autocrine compounds?

A

Compounds secreted into the extracellular fluid and act on the cell that created it

36
Q

What are the three types of receptors that water soluble chemical messengers bind to?

A

Channel, Enzyme or G-protein coupled receptors

37
Q

What do second messengers do?

A

Diffuse throughout the cell to surface chemical relays from the plasma membrane to the biochemical machinery inside the cell

38
Q

How do Protein Kinases phosphorylate other proteins?

A

By transferring a phosphate group to the protein from ATP

39
Q

How does Phosphorylation affect a protein?

A

The phosphate group is negatively charged so it causes the conformation of the protein

40
Q

What do G-protein coupled receptors activate?

A

Special membrane proteins called G proteins

41
Q

Where are G proteins found?

A

On the intracellular side of the plasma membrane (cytosolic surface)

42
Q

What do G-proteins function as a link between?

A

G protein coupled receptor and the effector protein

43
Q

What is the target of the G protein?

A

The effector protein

44
Q

What is the Effector protein?

A

The protein that the G protein will alter the activity of

45
Q

What are the two things that an Effector protein usually is?

A

An ion channel or an enzyme

46
Q

What do the Beta and Gamma subunit of G-proteins do?

A

Anchor the alpha subunit in the membrane

47
Q

What does the alpha subunit of the G protein bind to in it inactive state?

A

GTP

48
Q

What does the Alpha unit bind to in its active state?

A

GTP

49
Q

What alters the affinity of the Alpha sub unit for GDP?

A

The binding of an extracellular first messenger

50
Q

How does the alpha subunit on the G protein change in response to the binding of a first messenger to the membrane?

A

It responds through a conformational change that decreases its affinity for GDP and increases its affinity for GTP

51
Q

What occurs after the alpha subunit of the G protein binds to GTP?

A

The G protein is activated dissociates from the receptor and the GTP bound alpha subunit separates from the beta and gamma subunits

52
Q

What occurs after the Alpha subunit separates from the Beta and Gamma subunits?

A

It moves to its target protein in the membrane called, the effector protein

53
Q

What does Alpha subunit of G proteins move to after it has separated from the rest of the G protein?

A

The effector protein

54
Q

What does the Alpha unit do to the Effector protein?

A

Alter the activity of this target protein to produce some sort of response in the cell

55
Q

How does the Alpha subunit inactivate?

A

It hydrolyzes or breaks down GTP to GDP and inorganic phosphate

56
Q

What happens to the Alpha subunit once GTP is converted back to GDP?

A

The alpha subunit recombines with the other two unit and the G protein combines with the receptor

57
Q

Why does the Alpha Subunit not stay active for long?

A

Because it has intrinsic GTPase activity

58
Q

What is the meaning of the Alpha subunits intrinsic GTPase activity?

A

It means that it also functions as an enzyme that hydrolyzes ot breaks down GTP

59
Q

What are Stimulatory G proteins associated with?

A

Activation of an enzyme

60
Q

What are inhibitory G proteins associated with?

A

Inhibition of an enzyme

61
Q

Why is G protein activity slow?

A

Because it has many steps

62
Q

What do G protein catalyzed enzymes do?

A

Catalyze the production of second messengers in the cell

63
Q

What is the most common second messenger system found in the cells?

A

Cyclic AMP second messenger system

64
Q

What enzyme does the G protein activate in the Cyclic AMP system?

A

Adenylyl cyclase

65
Q

Where is the Catalytic site of Adenylyl Cyclase of the AMP messenger system located?

A

On the cytoplasmic surface of the plasma membrane

66
Q

What happens once the Alpha subunit binds to Adenylyl Cyclase in the Cyclic AMP messenger system?

A

Adenylyl cyclase catalyzes the conversion of cytosolic ATP into cyclic AMP

67
Q

What is the second messenger in the Cyclic AMP messenger system?

A

Cyclic AMP

68
Q

What does Cyclic AMP do once converted?

A

It diffuses through the cytoplasm and binds to Protein Kinase A

69
Q

What is another name for Protein Kinase A?

A

Cyclic AMP dependant protein kinase

70
Q

What is needed to activate Protein Kinase A?

A

The second messenger Cyclic AMP

71
Q

What does Protein Kinase A do?

A

Catalyzes the phosphorylation of proteins in the cell by transferring a phosphate group from ATP to cellular proteins

72
Q

What happens once Protein Kinase A phosphorylates cellular proteins?

A

Their activity is altered resulted in a cellular response

73
Q

How are the actions of Cyclic AMP terminated?

A

By the conversion of cyclic AMP to non cyclic AMP by the enzyme phosphodiesterase

74
Q

What is an example of a first messenger that exerts its effects through beta adrenergic receptors?

A

Epinephrine in the heart

75
Q

What receptors does Epinephrine act through?

A

Beta Adrenergic receptors

76
Q

What occurs in an Inhibitory Cyclic AMP system?

A

An inhibitory G protein which reduces the activity of adenylate cyclase producing less Cyclic AMP in the cell

77
Q

Where and how is calcium usually present?

A

In very low concentrations in the cytoplasm of cells (nanomolar range) and in higher concentrations in the extracellular fluid in the millimolar range

78
Q

Which organelles in the cell store calcium?

A

The Endoplasmic reticulum

79
Q

What is the normally low levels of calcium in the cytoplasm facilitated by?

A

Active transport systems found in the plasma membrane of the cell

80
Q

When Calcium enters the cell what does it cause the release of?

A

More calcium from the endoplasmic reticulum

81
Q

How does Calcium cause the release of more Calcium from the endoplasmic reticulum?

A

By binding to receptors on the endoplasmic reticulum causing ion channels to open

82
Q

What is Calcium Induced Calcium release?

A

When calcium allowed into the cell bind with the endoplasmic reticulum causing more calcium to be released into the cytoplasm of the cell

83
Q

What occurs once calcium levels are high enough in the cell?

A

Calcium acts as a second messenger and binds to Calmodulin, activating it

84
Q

What does the Calcium calmodulin complex do?

A

Activates a Calmodulin dependent protein kinase which phosphorylates proteins in the cell leading to a cellular response

85
Q

What is the Second messenger in the Calcium system?

A

Calcium

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