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Biochemistry > Cell Communication > Flashcards

Cell Communication Flashcards

1
Q

what is a signal transduction pathway?

A

a series of steps bu which a signal on a cells surface is converted to a cellular response

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2
Q

what signalling occurs in the NS?

A

chemical signalling between adjacent neurones

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3
Q

what are neural signals?

A

diffusing a short distance between neurone

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4
Q

what are neuroendocrine signals?

A

signals released from neurons but act on distant cells

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5
Q

what are pheromones?

A

chemicals released into the environment and act on a different individual

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6
Q

what is the direct mode of signalling?

A

direct signals from a cell-cell or a cell-matrix

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7
Q

what is the indirect mode of signalling?

A

secreted molecules

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8
Q

what is endocrine signalling?

A

signalling molecules are hormones that are carried through the circulation to act on a target cell

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9
Q

what is paracrine signalling?

A

signalling molecules released by one cell that acts upon neighbouring cells

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10
Q

what kind of signalling molecules act in a paracrine fashion?

A

neurotransmitters

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11
Q

what is autocrine signalling?

A

cells respond to signalling molecules that they themselves produce

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12
Q

what do animal and plant cells have that aids chemical signalling?

A

junctions that directly connect the cytoplasm of adjacent cells

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13
Q

what are local regulators?

A

messenger molecules that travel only short distances

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14
Q

what is an example of long distance signalling?

A

plants and animals using horomones to communicate

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15
Q

what are the three types of signalling molecules?

A

steroid hormones, nitric oxide and carbon monoxide and neurotransmitters

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16
Q

how do steroid hormones communicate with a cell?

A

diffuse across plasma. membrane and bond to receptors in the cytoplasm or the nucleus

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17
Q

where do steroid hormones come from?

A

all synthesised from cholesterol

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18
Q

what are examples of steroid hormones?

A

sex steroids and corticosteroids

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19
Q

compare thyroid hormone, vitamin D3 and retinoid acid

A

they all have different structures and functions yet share the same mechanism action

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20
Q

what is a steroid receptor superfamily?

A

transcription factors either as activators or repressors of transcription

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21
Q

what does NO do to a cell?

A

diffuses across the membrane and alters the activity of intracellular target enzymes

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22
Q

what causes the effects of NO to be local?

A

it is extremely unstable

23
Q

what is an example of NO action?

A

signalling if the dilation of blood vessels

24
Q

how can steroid hormone action cause the production of a protein?

A

the hormone enters the cell and binds to a receptor in the cytosol, the complex then enters the nucleus and binds to a specific gene where it acts as a transcription factor causing mRNA to be produced and eventually a protein

25
Q

what are the three processes that cells receiving signals are said to go through?

A

reception, transduction and response

26
Q

what happens during reception?

A

signal molecule binds to a receptor protein causing a conformational change

27
Q

what are intracellular receptors?

A

receptors found in cytosol or the nucleus of target cells

28
Q

what are the three main types of receptor?

A

G protein receptors, tyrosine kinases and ion channels

29
Q

what does an active G protein look like?

A

GDP is bound to the G protein which causes it to be active

30
Q

what does a tyrosine kinase do?

A

attaches phosphates to tyrosine molecules

31
Q

what is a phoshphotransferase?

A

a type of enzyme that transfers phosphate groups to substrates

32
Q

what does ion channels do?

A

acts as a gate when a lingo binds this causes a change in shape allowing ions through

33
Q

what happens during transduction?

A

multiple steps occur that amplify the signal e.g. multistep pathways

34
Q

what do multistep pathways do?

A

provide more opportunities for coordination and regulation

35
Q

what occurs at each step of a single transduction pathway?

A

a conformational change

36
Q

what kind of enzyme causes dephosphorylation?

A

phosphotases

37
Q

how can signals be transmitted in a signal pathway?

A

via a cascade of phosphorylations

38
Q

what are second messengers?

A

small, non-protein water soluble molecules

39
Q

what is the first messenger?

A

the extracellular signal molecule that binds to the membrane

40
Q

what receptors do second messengers take part in?

A

G protein receptors and tyrosine kinases

41
Q

how is ATP converted to cAMP?

A

adenylyl cyclase is responsible for the conversion in response to an extracellular signal

42
Q

how does activation of a G protein lead to the activation of protein kinase A?

A

G protein activated which activates adenylyl cyclase which then converts ATP to cAMP and cAMP then activates protein kinase A

43
Q

what makes calcium an important second messenger?

A

because cells can regulate its concentration

44
Q

what two things does a pathway leading to the increase in calcium involve?

A

inositol triphosphate (IP3) and diacylglycerol (DAG) as second messengers

45
Q

what happens in response?

A

a signal transduction pathway leads to regulation of one or more cellular activities

46
Q

where can the response occur?

A

in the cytoplasm or the nucleus

47
Q

what is a common response to a signalling pathway?

A

the regulation of function of a transcription factor

48
Q

how does epinephrine lead to the production of glucose?

A

signalling pathway activates protein kinase A, which then activates glycogen phosphorylase, which then converts glycogen to glucose 1 phosphate

49
Q

what are the 4 aspects if fine tuning the response?

A

amplifying the signal, specificity of the response, overall efficiency of the response and termination of the signal

50
Q

what do scaffolding proteins do?

A

enhance the overall efficiency of the response

51
Q

what gives specificity of a response?

A

different kinds of cells have different collections of proteins

52
Q

what helps to coordinate signals?

A

pathway branching and cross talk

53
Q

what causes termination of a signal?

A

the signal molecule leaving the receptor which causes the receptor to revert to its inactive state

Biochemistry (9 decks)

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