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BIO1111- Mary-Susan Pottsantone > Exam 2 (4) - Cell Communication > Flashcards

Exam 2 (4) - Cell Communication Flashcards

1
Q

What is the order in which we respond to a change in the environment?

A

stimulus–> receptor–> control center–> effector

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2
Q

what is true about responding to change in the environment?

A

order is the same between simple or complex cells
(all living things can detect change = signal transduction)

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3
Q

What are the different types of signaling?

A
  • Direct signaling
  • Contact-dependant
  • Autocrine
  • Paracrine
  • Endocrine Signaling
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4
Q

What is Direct Signaling?

A
  • gap junctions
  • signal passes through gap junction to adjacent cells
  • ex. cardiac muscle, neurons
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5
Q

What is Contact Dependent signaling?

A
  • membrane bound signals that bind to receptors.
  • ex. immune system –> antigen presenting cells ( phagocytosis)
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6
Q

Autocrine

A
  • cells release signals that affect themselves and some neighboring cells
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7
Q

Paracrine

A
  • only affect immediate neighbors ( like autocrine excluding itself)
  • ex. synaptic cleft ( rapid diffusion of neurotransmitter)
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8
Q

Endocrine signaling

A
  • group of specialized cells in an organ that releases hormones
  • signals that travel long distances to affect larger cells

-ex. glands

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9
Q

WHat is signal transduction at a cellular level?

A
  • Mechanism by which cells share information. Receive information generate a response
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10
Q

Signal Transduction: Stage 1

A

Receptor Activation

  • some signal molecule ( lingal) binds to a receptor

receptor ligand interaction leads to STP

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11
Q

Signal Transduction: Stage 2

A

Signal Transduction Pathway
- specific interactions
- creating a change
- proteins go conformational changes ( catalyse other reactions)

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12
Q

Signal Transduction : Stage 3

A

Cellular Response
-depends on cell and signaling molecule
- ex.
- altered metabolism or other cell functions
- altered cell shape
- altered gene expression
- etc.

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13
Q

agonist?

A

a ligand that ENHANCES cellular activity

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14
Q

antagonist?

A

a ligand that BLOCKS cellular activity.

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15
Q

what are the different kind of receptors?

A
  • intracellular receptors
  • cell surface receptors
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16
Q

How does an intracellular receptor work?

A

They respond to signaling molecules that can diffuse through the membrane.

  • lipids are soluble in other lipids
  • ex. steroid hormones, auxins
  • can attach to receptors in cytoplasm or directly onto DNA ( w/ Hormone Responsive Elements)
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17
Q

Where are the intracellular receptors located

A

-cytosol or nucleus

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18
Q

What are the forms cell surface receptors can take?

A
  • ligand gated ion channels
  • enzyme linked receptor
  • G coupled protein
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19
Q

Where are ligand gated ion channels common?

A
  • nerve and muscle cells
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20
Q

What do the ligand gated ion channels do?

A
  • help create action potentials
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21
Q

What are two features of enzyme linked receptors?

A
  • extracellular domain
  • catalytic domain
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22
Q

What is the extracellular domain?

A
  • hydrophilic
  • interacts w/ some signaling molecule
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23
Q

What is the catalytic domain?

A
  • part of the receptor involves a chemical reaction
  • some kind of kinase is involved ( 3 are common)
24
Q

What does kinase do?

A

phosphorylates –> activates

25
Q

What does it mean to phosphorolate?

A
  • take phosphate from ATP and attach it to something else –> energy
26
Q

what does phospotase mean ?

A
  • dephosphorylate ( opposite of kinase)
27
Q

What are the 3 subunits of G proteins?

A
  • a
  • B
    -y
28
Q

What happens after a signaling molecule binds to a GPCR in a plasma membrane?

A

GDP molecule is exchanged for GTP inside the cell

29
Q

What is GDP/GTP?

A

equivalent to ATP and ADP = E

30
Q

What does the G stand for in GDP and GTP?

A

Guanine

31
Q

What happens once GTP is available?

A
  • subunits disassemble
  • cellular response is triggered
32
Q

What terminates the cellular response of GPCR?

A

Hydrolysis of GTP–> GDP

33
Q

What does cAMP do as a second messenger?

A
  • activate or inactivate proteins w/in the cell
  • 2nd messenger
34
Q

When is the signal terminated for cAMP?

A
  • phosphodiesterase
  • converts cAMP to AMP
35
Q

What is considered the extracellular domain in the GPCR?

A

The G protein-coupled receptor outside of the cell.

36
Q

What is the catalytic domain of the GPCR?

A

The heterotrimeric G protein

37
Q

What is the epidermal growth factor? what is it an example of?

A

It is an example of the enzyme-linked receptor
- tissue repair, mitosis

38
Q

What is the 2nd messenger mechanism?

A

Producing a small molecule that can relay a signal inside the cell.

39
Q

why does there need to be a 2nd messenger?

A

1st messenger cannot cross into membrane

can only do its job by interacting w/ receptors in the membrane.

40
Q

What is important to remember about receptor pathways?

A

The cAMP can be stimulatory at times and then inhibitory at times. ( depends on receptor and cell shit)

41
Q

What are two traits of a 2nd Messenger?

A
  • short life span
  • increase amplification/speed
42
Q

How is the DAG/IP3 2nd messenger mechanism different to cAMP?

A

It ends up having 3 -2nd messengers.

43
Q

What are the 3 messengers made in the DAG/IP3 mechanism?

A

-DAG
-IP3
-Calcium

44
Q

What is step 1 of the cAMP cycle?

A
  1. signal molecule interacts with GPCR–> activates it
45
Q

What is step 2 of the cAMP cycle?

A

GTP and G protein bind
- subunits dissasociate

46
Q

What is step 3 of the cAMP cycle?

A
  • subunit binds to the effector ( adenylate cyclase)
    -synthesis of cAMP
47
Q

What is step 4 of the cAMP cycle?

A
  • activates kinase
48
Q

What is step 5 of the cAMP cycle?

A

-kinase phosphorylates, cause specific reactions

49
Q

What is the relay GTP?

A

Inhibits effector enzymes.

50
Q

What is Step 1 of the DAG/IP3 mechanism?

A
  1. signal molecule interacts with GPCR–> activates it
51
Q

What is Step 2 of the DAG/IP3 mechanism?

A
  1. GTP and G protein bind
    - subunits disassociate
52
Q

What is step 3 of the DAG/IP3 mechanism?

A
  • subunit binds to the effector ( phospholipase)
53
Q

What is step 4 of the DAG/IP3 mechanism?

A
  • breaks down membrane phospholipid into 2–> 2nd messenger molecules. ( DAG/IP3)
54
Q

What is step 5 of the DAG/IP3 mechanism?

A
  • DAG activates kinase C
  • IP3 binds to smooth ER–> Calcium Released
55
Q

What is step 6 of the DAG/IP3 mechanism?

A
  • 3-2nd messengers direct responses of the target cell
56
Q

Where does DAG go? What does it do?

A
  • inside membrane
  • hydrophobic
  • activates kinase C
57
Q

Where does IP3 go? What does it do?

A
  • into cytoplasm
  • binds to smooth ER–> calcium is released

BIO1111- Mary-Susan Pottsantone (17 decks)

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