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BSCI330 SPRING > exam 2 cellular communication > Flashcards

exam 2 cellular communication Flashcards

1
Q

how do cells communicate with each other

A

receptors, which bind to signal molecule ligands

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2
Q

what is the outcome of signaling

A

rapid changes in protein function snd/or slower changes in gene expression

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3
Q

how do hydrophobic ligands cross membranes

A

easily to activate intracellular receptors

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4
Q

how do hydrophilic ligands cross membranes

A

they bind to cell-surface transmembrane receptors

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5
Q

what does signal transduction from cell-surface receptors require

A

the activation or generation of second messengers, which transmit the signals from the cell surface to the effectors

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6
Q

what are the three basic modes of signaling

A
  • ion channels
  • enzyme-coupled receptors
  • G-protein-coupled receptors
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7
Q

what are the three steps of signaling

A

reception, transduction, response

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8
Q

what signaling can secreted molecules do

A

paracrine, endocrine, and synaptic siganling

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9
Q

what is paracrine signaling

A

act as local mediators, affecting only cells in the immediate environment of the signaling cell

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10
Q

what is endocrine signaling

A

travel long distances through the bloodstream to act on distant targets

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11
Q

what is synaptic signaling

A

travel via axons

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12
Q

what is autocrine signaling

A

a cell secretes signal molecules that can bind back to its own receptors

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13
Q

when is autocrine signaling useful

A

in positive or negative feedback loops - allow cells to amplify the signal or make one that is self-limited

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14
Q

what is contact-dependent siganling

A

signal molecules remain bound to the surface of the signaling cell and influence only cells that contact it

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15
Q

what can signaling molecules do/alter

A

slowly or rapidly alter the function of a target cell or flip the protein on or off or change the amount of protein to alter protein function

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16
Q

can signals work together

A

yes and cells can be programmed to respond to one combination of signals by growth/division, and these can promote survival

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17
Q

what happens when cells are deprived of their signals

A

they activate apoptosis

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18
Q

how do cellular responses vary

A

according to the receptor proteins the cell has and the intracellular signaling machinery the cell uses to interpret them

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19
Q

what are morphogens

A

molecules that diffuse out from signaling centers in developing tissues, creating a morphogen concentration gradient

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20
Q

how do cells adopt different fates from each other

A

depending on their position in the gradient. in this way layers of cells develop, each with a different function based on their concentration

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21
Q

how can concentration amount be useful

A

can determine where molecules are in the cell based on it

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22
Q

what are the types of signals

A

mechanical, light, heat, chemical

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23
Q

what forms do chemical stimuli come in

A

amino acids, small peptides, proteins, nucleotides, steroids, fatty acid derivatives, dissolved gasses

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24
Q

what does exocytosis do

A

signal molecules are secreted from the signaling cell into the extracellular space

25
Q

how are some cells exposed to extracellular space

A
  • exposed to the extracellular space while remaining tightly bound to the signaling cell’s surface
  • released by diffusion through the plasma membrane
26
Q

what happens with lipid soluble signaling molecules

A

they can simply diffuse across the plasma membrane

27
Q

what signal molecules are lipid soluble

A

steroid hormones and gaseous signaling molecules

28
Q

what happens with steroid hormones

A

they travel to their target cells via carrier proteins and bind to intracellular receptors, which can either be cytosolic or nuclear

29
Q

what family are receptors for steroid hormones a part of

A

the nuclear receptor subfamily

30
Q

prior to ligand binding, what do receptors bind to

A

an inhibitory protein and are inactive

31
Q

what does ligand binding cause

A

a conformational change in the receptor, which causes an inhibitory protein to dissociate

32
Q

what does a conformational change expose

A

exposes a site which binds to the promoter region upstream of a specific targeted gene

33
Q

what occurs with transcription of a targeted gene

A

it’s then increased, producing specific proteins leading to changes in cell behavior

34
Q

what happens to hydrophilic/lipid insoluble signals

A

they cannot cross cell membranes and they must bind to sites on cell surface receptors

35
Q

what are ligand-gated ion channels

A

binding of ligands to the channel causes it to open and allows specific ions to flow through

36
Q

what are enzyme coupled receptors

A

activate an enzyme when activated by a signal molecule binding to a receptor

37
Q

what are G-protein-coupled receptors

A

activation of receptor causes a change in GTP vs GDP binding of a switch protein, which turns downstream enzymes on or off

38
Q

what are ion-channel-coupled receptors involved in

A

synaptic signaling - opened/closed by neurotransmitters

39
Q

what do ion-channel-coupled receptors do

A

alter ion permeability to cause membrane potential changes

40
Q

what family are G-protein-coupled receptors from

A

large family of multi-pass transmembrane proteins

41
Q

what do G-protein-coupled receptors indirectly regulate

A

the activity of a nearby target protein in the membrane

42
Q

what do G-protein-coupled receptors contain

A

a GTP binding protein complex that acts as the middle man between an activated receptor and its target

43
Q

what do enzyme-coupled receptors function as

A

protein kinases

44
Q

what do enzyme-coupled receptors indirectly regulate

A

the activity of a nearby target protein that is in kinase cascade

45
Q

what does the kinase cascade allow for

A

rapid amplification of signals

46
Q

what carriers a first messenger signal across the plasma membrane

A

cell-surface receptors

47
Q

what do second messengers do

A

they are a combination of activated enzymes and small intracellular molecules that amplify the signal and spread it through the cell

48
Q

what regulates a cell’s responses

A

activated effector proteins

49
Q

what are molecular switches activated by

A
  • kinases/phophatases: phosphorylation/dephosphorylation

- GTPases/GTP-binding proteins

50
Q

what forms protein complexes called signaling complexes

A

enzymes activated by a receptor protein

51
Q

what do signaling complexes regulate

A

speed, efficiency, specificity of a cellular response

52
Q

how can signaling complexes be organized

A

organized around a scaffold protein, assembled following receptor activation or on phosphorylated lipids

53
Q

what do enzyme-coupled receptors interact with

A

receptor tyrosine kinases, which dimerize and phosphorylate themselves upon ligand binding

54
Q

what do receptor tyrosine kinases allow for

A

recruitment of other ligands to bind and increases substrate range of kinase to phosphorylate other targets

55
Q

what activates the GTPase signaling protein, Ras

A

tyrosine kinase, which covalently attaches to lipid anchor (inner leaflet of plasma membrane)

56
Q

what does Ras initiate

A

a cascade of phosphorylation events mediated by a group of MAP kinases

57
Q

when bound to a ligand, what does a G-protein-coupled receptor do

A

releases GDP and binds to GTP

58
Q

when not bound to a ligand, what does a G-protein-coupled receptor do

A

it’s bound to GDP

59
Q

what is cAMP

A

a common second messenger

BSCI330 SPRING (24 decks)

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