cell signalling

Question 1

why do cells need to respond to their environment?

Answer 1

• respond to their environment

- survive and communicate

Question 2

when did cell signals become a thing?

Answer 2

early history of life

as life became more complicated, so did signals

Question 3

what do most cell communicate through?

Answer 3

chemicals:
hormones
growth factors
inhibition

Question 4

what do cells respond to

Answer 4

temp
osmosis
stress
nutrients

Question 5

how do batceria/ prokaryotes respond to signals

Answer 5

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

Question 6

how can bacteria respond to the new signals

Answer 6

synthesise new proteins to optimise survival

activate gene expression to make new enzymes

Question 7

how do yeast respond to each other and partneres

Answer 7

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

Question 8

what allows yeast to become diploid durin mating?

Answer 8

two diffferent mating factors of genotypes allow sex and diploid mating

Question 9

what signals so multicellular organisms respond to?

Answer 9

phyical and environmental presence of other cells

where they are, right or wrong

Question 10

what makes multicullular cells stay alive

Answer 10

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

Question 11

how does place impact cells

Answer 11

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

Question 12

what makes cancer cells different?

Answer 12

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

Question 13

types of stimuli for cells

Answer 13

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

Question 14

what is signal transduction

Answer 14

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

Question 15

how are extran stimuli converte to cellular responses?

Answer 15

cell juctions
cell-cel recognition
paracrine
synapses
endocrine

Question 16

how do cell junctions work for communication

Answer 16

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

Question 17

what type of cell junctions are there?

Answer 17

in animal cells: gap junctions

in plant cells: plasmodesmata

Question 18

how does cell-cell recognition work for communication?

Answer 18

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

Question 19

how is paracrine signalling used

Answer 19

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

Question 20

how do the paracrine signal fators work

Answer 20

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

Question 21

how does synaptic signals work

Answer 21

specialised form is paracrine signals

highly directional compared to normal paracrine

Question 22

what is endocrine and hormone signalling

Answer 22

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

Question 23

difference between paracrine and endocrine

Answer 23

paracrine uses blood stream and has a wide effect

paracrine si very localised

Question 24

steps of the signal transduction pathway

Answer 24

receptor on surface –> signals in cell –> response

Question 25

three phases of cell signalling

Answer 25

1. reception or recognition
2. tranduction
3. response

Question 26

process of cell signalling reception/ recognition

Answer 26

target cells detect signal from outside

chemical binds to protein on cellular surface

Question 27

what is a ligand

Answer 27

external stimuli that binds to a receptor

its a first messenger

Question 28

how does transduction occur in cell signalling

Answer 28

converts one type of signal into another ( the initial stimulus or ligand binding) into another signal such as internal signal or second messengers.

Question 29

how are cell signals amplified?

Answer 29

enzymes

Question 30

types of receptors

Answer 30

ion channel-linked
G-protein linked
enzyme linked

Question 31

what is a G-protein linked receptor

Answer 31

loops inside and outside the membrane to connect with ligands or other proteins inside the cell

Question 32

how do tyrosine-kinase receptors work

Answer 32

1. resting in cell, unstimulated
2. receptor binds ligand and becomes activated
3. recruits different effectors to propagate the signal further into the cell

Question 33

explain dimerisation using tryosine kinase receptors

Answer 33

• 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

Question 34

what is an effector

Answer 34

enzymes in the cell that transduce ligand actavated signals into the cell
catalyse the formation of second messenger moelcules

Question 35

whats a second messenger molecule

Answer 35

small chemical that act as messengers

carry signals from one part of the cell to another through diffusion

Question 36

what is ras-MAP

Answer 36

common growth factor for activating signalling pathways
regulates changes of gene expression and cell cycle
activation of this pathway is linked to many cancers

Question 37

describe a simple signalling cascade

Answer 37

ligand, first messenger
cell surface receptor
effector  enzyme, second mesenger
amplifiers 
target response proteins

Question 38

what are the key concepts in cell signals

Answer 38

the process is highly specific and organised
molecular switches are used
cascade amplifies the signal

Question 39

what is molecular recognition?

Answer 39

ligand- receptor interaction determines specificity of the signalling
lock and key fit of the ligands fitting the receptor

Question 40

molecular switches

Answer 40

receptor phosphorylation leading to signalling molecules binding and activation is a switch

Question 41

how are signals amplified?

Answer 41

receptors when activated activate transducers and continue till negative feedback. these can modify cell behaviour.

Question 42

why is amplification used?

Answer 42

more efficient

Question 43

ways signals are amplified

Answer 43

• ion channels

- chain enzymes in series

Question 44

how do chain enzymes in series work

Answer 44

amplification at each step in the series causes more proteins to be activated
much more efficient process

Question 45

what response can a cell have from a signal?

Answer 45

secretions into environment
change in cytoskelton
change in function
move the cell
change gene expression
metabolism
aactivation/inhibition of pathways
activation of certain genes

Question 46

what is a target response protein

Answer 46

something that brings about the change in the celll

signal component at the end of the pathway