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Cells and Genes SF1 > Social Cells > Flashcards

Social Cells Flashcards

1
Q

What are the extracellular molecules that bind to receptors?

A

Ligands

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2
Q

what is paracrine signalling?

A

cells signalling a neighbouring cell

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3
Q

what is autocrine signalling?

A

Cell signals itslef

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4
Q

describe endocrine signalling

A

hormone ligand, slow release, long effect, long distance

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5
Q

describe synaptic signalling

A

neurotransmitter ligand, long distance, rapid release

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6
Q

what is juxtacrine signalling?

A

contact dependent signalling, proteins in the membrane and cell interact

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7
Q

what is a local mediator?
and give an example

A

paracrine ligands, medium release time
ex) histamines, thromboxane, leukotrienes.

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8
Q

what are the 4 types of receptors?

A

ion channel coupled
G protein Coupled
Enzyme Coupled
Nuclear receptors

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9
Q

describe the different types of passive transport

A

simple diffusion: small non polar molecules can move throughout the bilayer or through protein channels
facilitated diffusion: molecule specific, uses carrier proteins, limited capacity sos movement is regulated

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10
Q

describe primary and secondary active transport

A

primary: uses ATP to move substances against their concentration gradient
secondary: transports a solute in the direction of the increasing electrochemical potential using facilitated diffusion.

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11
Q

what is a uniporter

A

pump that pumps one ion and out

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12
Q

name the ion pump that pumps 2 molecules across the membrane in the SAME direction

A

Symporter

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13
Q

name the ion pump that pumps 2 molecules across the membrane in opposite directions at the same time

A

Antiporter

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14
Q

describe the NA/K pump

A

uses ATP to pump 3 Na out and 2 K in

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15
Q

what is an example of secondary active transport

A

Glucose movement: Low Na in cell causes Na to move in via FD so charge inside the cell increases, due to this glucose is cotransported into the cell

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16
Q

name the different type of ion channels

A

ligand gated
voltage gated
leak channels
stretch activated

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17
Q

how may Voltage gated ion channels open

A

depends on the electrochemical gradient. If the membrane around the channel has been depolarised, there will be a conformational change in the channels protein structure

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18
Q

how are stretch activated ion channels opened

A

a disruption in the membrane leads to changing tension, compression causes a conformational change

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19
Q

what is a compliant cell

A

when a cell expresses the correct receptor

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20
Q

how is there variation in receptor responses

A

receptors have different isoforms, which may all be activated at once

some have different affinities for different ligands

21
Q

what is the speed of a ligand gated ion channel receptor and why?

A

channels open in a millisecond - synaptic

22
Q

how to ligand gated ion channel receptors get activated

A

ligand binds to the receptor and causes a conformational change, allowing the secondary messenger to interact, triggering a cascade reaction within the cell.

23
Q

Name for converting external signals to a cellular response

A

signal transduction

24
Q

what is the speed of G protein coupled receptors?

A

slower than ion channeled receptors,
medium speed as are used by multiple types of messengers

25
Q

what are functions of G protein coupled receptors?

A

immune response
inflammation
autonomic NS

26
Q

how are G protein coupled receptors activated?

A

ligand binds which causes a conformational change.
the alpha subunit of the G protein binds to the receptor, causing the Alpha GDP component of the G protein to separate from the Beta Gamma component.
Both components move along the membrane and interact with the signalling system.

GDP on the alpha subunit is replaced with GTP when it dissocated.
GTP gets hydrolysed back to GDP by GTPase
this causes the Alpha and beta gamma subunit to rejoin.

27
Q

what are the components within a G coupled receptor

A

binding domains and 7 alpha helices

28
Q

what are the 4 types of G proteins?
and what makes them different?

A

Gas, Gai, Gao, Gaq
have different alpha subunits and have many different complementary G protein coupled receptors and secondary messengers.

29
Q

what is the function of Gao protein

A

interacts with K/Ca ion channels.

30
Q

what is the function of Gas and Gai proteins

A

stimulate adenyl cyclase which converts ATP to cyclic AMP

31
Q

what is the function of Gaq protein

A

catalyses the production of IP3 and DAG from phospholipase C

32
Q

what is the speed of enzyme linked receptors?

A

transduction takes minutes/hours.
are slower than GPCRs

33
Q

what functions do enzyme linked receptors aid?

A

cell growth/ devision
inflammation
immune response

34
Q

describe the structure of enzyme linked receptors

A

they have an extracellular binding domain and a catalytic site within the cell.

35
Q

what is the most common enzyme linked receptor?
and describe how it is activated

A

Kinase linked receptor

the alpha helix proteins come in pairs, so the signal binds to the 2 proteins, bridging them together forming a dimer.
this becomes active kinase

36
Q

descrive what happens after the kinase linked receptor is activated

A

tryosine (the alpha helix) gets phosphorylated and becomes a docking site for intracellular relay proteins.
when these proteins get activated it leads to a cascade reaction in the cell

37
Q

what terminated downstream signalling (of kinase linked receptors) ?

A

tryosine phosphatases

38
Q

what processes to RAS and P13 Kinase play a part in?

A

cell division/growth/ differentiation
used as anticancer drugs

39
Q

what is the JAK STAT pathway?

A

inflammation, activated by cytokines

40
Q

what drug inhibits JAK kinase? and why is it used?

A

Octacitnib
targets cytokines to treat inflammation, usually for allergies or dermatitis

41
Q

what is the speed of nuclear receptors? and why?

A

very slow with long lasting effects as they are hormone receptors

42
Q

where are nucear receptors found?

A

within the cells, so lipid soluble ligands must enter the cell

43
Q

what are type 1 nuclear receptors?

A

bind to ligands in the cytoplasm
bind to DNA as homodimers

44
Q

what are type 2 nuclear receptors?

A

are in the nucleus.
Hormone binds to the RXR retinoid receptor.
are heterodimers

45
Q

describe the type 1 nuclear receptor pathway

A

hormone (oestrogen or progesterone) bind to the receptor, leading to the dissociation of HSP
the receptor and HP (HSP dissociate) enter the nucleus.
here they interact with coreceptors and coactivators
these act as transcription factors

46
Q

describe the type 2 nuclear receptor pathway

A

hormone (thyroxine, retanoic acid) dind to RXR receptor which is bound to a corepressor (ensures the receptor is inactive untill hormone binds).
Coactivator induced to act as a transcription factor.

47
Q

describe autologous receptor homeostasis

A

the conc of receptor can change due to their activation - positive feedback

48
Q

describe heterologous receptor homeostasis

A

conc of receptor changes depending on a different nuclear receptors activation.

49
Q

when are nuclear receptor drugs used?

A

hormone deficiencies
hormone antagonists
treat non endocrine diseases that prevent endocrine sectretion

Cells and Genes SF1 (11 decks)

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