cell signalling Flashcards

1
Q

why do cells need to respond to their environment?

A
  • respond to their environment

- survive and communicate

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2
Q

when did cell signals become a thing?

A

early history of life

as life became more complicated, so did signals

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3
Q

what do most cell communicate through?

A

chemicals:
hormones
growth factors
inhibition

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4
Q

what do cells respond to

A

temp
osmosis
stress
nutrients

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5
Q

how do batceria/ prokaryotes respond to signals

A

moving towards or away from the signal using flagella for motion
spinning of the flagella causes the bacteria to move direction

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6
Q

how can bacteria respond to the new signals

A

synthesise new proteins to optimise survival

activate gene expression to make new enzymes

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7
Q

how do yeast respond to each other and partneres

A

exchange of chemicals to find partners
mting factors are short peptides about 12 amino acids
secreted into environment
yeast move along concentration gradient to bind in mating
two different mating factors based on sexes to give two genotypes

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8
Q

what allows yeast to become diploid durin mating?

A

two diffferent mating factors of genotypes allow sex and diploid mating

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9
Q

what signals so multicellular organisms respond to?

A

phyical and environmental presence of other cells

where they are, right or wrong

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10
Q

what makes multicullular cells stay alive

A

being in the correct place means they get correct signals and can stay alive

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11
Q

how does place impact cells

A

the matrix cells are in will contain proteins to tell them they are in the correct place and can survive
different tissues make differing growth factors for cells to bind to

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12
Q

what makes cancer cells different?

A

they no longer respect environmental signals
dont need signal for growth or death
become independent through mutations

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13
Q

types of stimuli for cells

A
growth factors
matric contact
hormones
light photons
cell to cell contact
odorants, smell and taste
touch
temperature
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14
Q

what is signal transduction

A

mechanism by which a cell is able to respond or adapt to changes in the envirnment

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15
Q

how are extran stimuli converte to cellular responses?

A
cell juctions
cell-cel recognition
paracrine
synapses
endocrine
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16
Q

how do cell junctions work for communication

A

exhcange of ions and small molecule through pores between close cells
protein pores allow adjacent cels to communicate or use ion channels too

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17
Q

what type of cell junctions are there?

A

in animal cells: gap junctions

in plant cells: plasmodesmata

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18
Q

how does cell-cell recognition work for communication?

A

two cells can recognise each other and their context through surface receptors
this type of signalling is for survival and to tell cells they are in the correct place

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19
Q

how is paracrine signalling used

A

occurs locally
growth factors for example made and secreted by transmitting cells
diffuse locally until they encounter target cells with correct receptors

20
Q

how do the paracrine signal fators work

A

growth factors for example made and secreted by transmitting cells
diffuse locally until they encounter target cells with correct receptors
factor creates a concentration gradient telling the cell how close or far it is from the signals by how much they recieve

21
Q

how does synaptic signals work

A

specialised form is paracrine signals

highly directional compared to normal paracrine

22
Q

what is endocrine and hormone signalling

A

long distance signals that use the blood system to transport sigals throught the whole body to reach targets

23
Q

difference between paracrine and endocrine

A

paracrine uses blood stream and has a wide effect

paracrine si very localised

24
Q

steps of the signal transduction pathway

A

receptor on surface –> signals in cell –> response

25
three phases of cell signalling
1. reception or recognition 2. tranduction 3. response
26
process of cell signalling reception/ recognition
target cells detect signal from outside | chemical binds to protein on cellular surface
27
what is a ligand
external stimuli that binds to a receptor | its a first messenger
28
how does transduction occur in cell signalling
converts one type of signal into another ( the initial stimulus or ligand binding) into another signal such as internal signal or second messengers.
29
how are cell signals amplified?
enzymes
30
types of receptors
ion channel-linked G-protein linked enzyme linked
31
what is a G-protein linked receptor
loops inside and outside the membrane to connect with ligands or other proteins inside the cell
32
how do tyrosine-kinase receptors work
1. resting in cell, unstimulated 2. receptor binds ligand and becomes activated 3. recruits different effectors to propagate the signal further into the cell
33
explain dimerisation using tryosine kinase receptors
- when ligand binds it changes shape of molecules - enzymatic part phosphorylates tyrosin - leads to activation of proteins in a bindin equence leading to cellular response - tyrosin phosphylates shows receptor is activated, - proteins can now bind
34
what is an effector
enzymes in the cell that transduce ligand actavated signals into the cell catalyse the formation of second messenger moelcules
35
whats a second messenger molecule
small chemical that act as messengers | carry signals from one part of the cell to another through diffusion
36
what is ras-MAP
common growth factor for activating signalling pathways regulates changes of gene expression and cell cycle activation of this pathway is linked to many cancers
37
describe a simple signalling cascade
``` ligand, first messenger cell surface receptor effector enzyme, second mesenger amplifiers target response proteins ```
38
what are the key concepts in cell signals
the process is highly specific and organised molecular switches are used cascade amplifies the signal
39
what is molecular recognition?
ligand- receptor interaction determines specificity of the signalling lock and key fit of the ligands fitting the receptor
40
molecular switches
receptor phosphorylation leading to signalling molecules binding and activation is a switch
41
how are signals amplified?
receptors when activated activate transducers and continue till negative feedback. these can modify cell behaviour.
42
why is amplification used?
more efficient
43
ways signals are amplified
- ion channels | - chain enzymes in series
44
how do chain enzymes in series work
amplification at each step in the series causes more proteins to be activated much more efficient process
45
what response can a cell have from a signal?
``` secretions into environment change in cytoskelton change in function move the cell change gene expression metabolism aactivation/inhibition of pathways activation of certain genes ```
46
what is a target response protein
something that brings about the change in the celll | signal component at the end of the pathway