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Exam 2 (PARP) > Cell Signaling and Signal Transduction > Flashcards

Cell Signaling and Signal Transduction Flashcards

1
Q

__________ receptors convert chemical signals into electrical ones.

A

Ion channel-linked receptors

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2
Q

Which compound does PKA phosphorylate in the nucleus and what affect does this have?

A

CREB. CREB binds the target gene which leads to an increase in transcription, followed by translation.

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3
Q

Inositol Phospholipid Pathway

A
  1. Signaling molecule binds to a G-protein linked receptor
  2. G-protein alpha subunit activated
  3. The alpha subunit activates a phospholipase
  4. Phospholipase breaks down Pl 4,5-bisphosphate
  5. The break down of Pl 4,5-bisphosphate results diacylglycerol and IP3
  6. IP3 will bind to IP3 receptors on the ER membrane
  7. Calcium released
  8. Calcium can activate protein kinase C
  9. Protein kinase C interacts with diacylglycerol which will result in further downstream affects.
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4
Q

A receptor signal molecule that is activated by cleavage?

A

Notch

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5
Q

What occurs in primary transduction? What steps follow?

A

The transmembrane protein binds the ligand

A number of intracellular relays can occur so that signal can be modified, amplified, and divered to multiple targets.

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6
Q

How is the alpha subunit of the G-protein inactivated?

A

The hydrolysis of the GTP by the alpha subunit inactivates this subunit and causes it to dissociate from the target protein

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7
Q

Examples of Small Signaling Molecules that Bind to Nuclear Receptors

A

Cortisol

Estradiol

Testosterone

Thyroxine

Vitamin D

Retinoic acid

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8
Q

What component downregulated the alpha subunits GTPase activity? What affect does this have?

A

GTP gamma S; helps the alpha subunit to remain active for a very long time

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9
Q

Bifurcation proteins

A

Split the cell into 2 signaling pathways

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10
Q

________ and ________ depend on G-protein-linked receptors that regulate cyclic-nucleotide- gated ion channels.

A

Smell; vision

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11
Q

Example of a metabotropic recepter pathway

A
  1. The Metabotropic receptor binds to the G-protein
  2. Adenylate cyclase is activated
  3. cAMP is activated
  4. Protein Kinase A is activated
  5. The channel will close and no potassium will be able to exit the cell

* Indirect affect

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12
Q

In the intracellular pathway, in what way are the metabolic enzyme, gene regulatory protein, and cytoskeletal protein affected by the cascade?

A

Metabolic emzyme: Altered metabolism

Gene regulatory protein: Altered gene expression

Cytoskeletal protein: Altered shape or movement

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13
Q

How many subunits does an inactive protein kinase A have?

A

4 (2 regulatory and 2 catalytic)

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14
Q

What happens to neurotransmitters once they are released into the synpatic cleft and bind to the receptor?

A

The neurotransmitters are broken down by enzymes found in the synapse. They are then taken up by glia cells or recycled back intot he nerve cell

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15
Q

Adaptor protein

A

Link one signal pathway to another signal pathway

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16
Q

What does PDGF, FGF, and NGF stand for?

A

Platelet derived growth factor receptor, fibroblast growth factor, and nerve growth factor

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17
Q

What happens in the cAMP pathway?

A

cAMP acts on the protein kinase A

Once cAMP binds to PKA, the subunits break up and you get the active PKA catalytic subunits

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18
Q

Intracellular signaling proteins that act as molecular switches

A

Signaling by Phosphorylation

Signaling by GTP-binding protein

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19
Q

Scaffold proteins

A

Combine multiple signal proteins together forming a complex

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20
Q

Which type of channels found in gap junctions allow for bidirectional flow? What type of response does this allow for?

A

Connexon; Fast

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21
Q

What happens in intracellular signaling?

A

Small hydrophobic molecules cross the membrane and float into the nucleus, where they bind to the intracellular recptors and can cuase changes to gene transcription

22
Q

__________ make the effects of PKA and other protein kinases transitory.

A

Protein phosphatases

23
Q

Enzyme- linked Cell-Surface Receptors are activated by ___________

A

Growth factors

24
Q

____________ is a signaling molecule that can activate both ionotropic and metabotropic receptors

A

Glutamate

25
Q

Enzyme-linked Receptors (Mechanism)

A
  1. Dimerize
  2. Activate other enzymes
26
Q

A cell is dependent on multiple extracellular signals that tell it whether to:

A

Survive

Divide

Differentiate

Die

27
Q

G-protein linked Receptors (Mechanism). Type of receptor? Type of protein?

A
  1. Signal molecule binds receptor
  2. The receptor activates a G-protein that is also sitting in the membrane
  3. The G- protein gets activated and splits into two components (alpha and beta-gamma)
  4. The G-protein can activate other enzymes that are sitting on the enzyme
  5. The G protein can have kinase activity and phosphoylate/ activate other proteins

Metabotropic Receptor

Transmembrane protein

28
Q

Messender proteins

A

Carry signal from one part of the cell to another

29
Q

What affect does Cholera Toxin have in cAMP, by what mechanism?

A

Cholera Toxin prevents the alpha subunit from being hydrolyzed by the phosphate , so the alpha subunit will remain in its active form and stimulate adenylyl cyclase indefinitely. This will result in prolonged, elevated cAMP levels, which can result in a large influx of chloride and water in the gut. Final product is severe diarrhea.

30
Q

Which has greater specificity endocrine signaling or synaptic signaling?

A

Synaptic signaling

31
Q

Ion channel linked receptor mechanism. What type of receptor? What type of protein?

A
  1. Signal molecule binds the receptor
  2. The receptor undergoes a conformational change into an ion channel
  3. Specific ions are able to pass into and out of the the channel

Ionoctropic receptors

Transmembrane protein

32
Q

Signaling by Phosphorylation

Types

When is it active, when is it not?

A

Types: Serine/ Threonine kinases, Tyrosine kinases

Active when phosphorylated

Inactive when dephosphorylated

33
Q

What is the difference between ionotropic and metabotropic receptors?

A

Ionotropic receptors have a direct affect on the ion channel and metabotropic receptors do not.

34
Q

_________ activates adenylyl cyclase.

A

Stimulatory G protein (Gs)

35
Q

How does cortisol affect transcription? (mechanism)

A
  1. Cortisol crosses the membrane
  2. Once cortisol is near the receptor, the receptor undergoes a conformational change, which activated it
  3. Cortisol binds the receptor
  4. Cortisol-receptor complex travels the nucleus and binds to regulatory region of the targe gene
  5. Activates transcription
36
Q

Which type of Cell-Surface Receptor has slow and direct rapid responses?

A

Enzyme linked

37
Q

Latent regulatory proteins go to the __________

A

Nucleus

38
Q

What response does acetylcholine induce in the heart muscle, salivary gland cell and skeletal muscle?

A

Heart muscle: Decreased rate and force of contraction

Salivary gland: Secretion

Skeletal muscle: Contraction

39
Q

_________ inhibits adenylyl cyclase.

A

Inhibitory G protein (Gi)

40
Q

Singling by GTP-Binding Protein

A

Active when GTP is bound and inactive when GDP is bound

41
Q

Three types of cell-surface receptors

A

Ion- channel linked receptors

G-protein linked receptors

Enzyme-Linked Receptors

42
Q

What component can enhance the binding of the target protein? What other roles does this component have?

A

RGS; Plays a role in shutting off the G-protein mediated response

43
Q

In a group of identical signaling cells, each cell receives a strong ____________ signal. Why?

A

Autocrine. Due and increase in conentration

44
Q

What gas can cross the plasma membrane and activate the intracellular enzymes directly?

A

Nitric Oxide

45
Q

What happens in extracellular signaling?

A

A hydrophilic signal molecule bind to a cell-surface receptor, which can lead to an intracellular cascade or secondary messsenger cascade

46
Q

In which type of signaling does the signal last longer, sypaptic or endocrine?

A

Endocrine becuase the signaling mechanism takes time.

47
Q

How do hydrophobic molecules travel through the blood stream?

A

On carrier proteins

48
Q

Pertussis Toxin

A

Causes whopping cough. It acts on the inhibitory G protein which will result in an inactive alpha subunit, which will result in adenylyl cyclase not being activated.

49
Q

Adenylyl cyclase makes cAMP out of _________

A

ATP

50
Q

What happens after the alpha subunit of the G-protein complex is inactivated?

A

It reassembles with the beta-gamma subunit to reform and inactive G-protein

51
Q

Relay proteins

A

Signal being communicated

52
Q

Transducer proteins

A

proteins that receive and help process information so that proper action by the cell ensues.

Exam 2 (PARP) (17 decks)

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