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ENI 2 > hormones and cell signalling > Flashcards

hormones and cell signalling Flashcards

1
Q

how do signalling molecules work

A
  • receptors are expressed by target cells
  • if no receptor exists for a given signal, there is no response
  • ligands are the signalling molecules
  • ligands bind to a site on the receptor
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2
Q

what is autocrine signalling

A

affects the cell producing them

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3
Q

what is paracrine signalling

A

diffuse short distance to affect cells nearby

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4
Q

what is endocrine signalling

A

acts on target cells distance from site of synthesis

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5
Q

what are the consequences of cell signalling

A
  • survival
  • divide
  • differentiate
  • die
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6
Q

what are the 2 types of hormones

A
  • lipid soluble
  • water soluble
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7
Q

discuss lipid soluble hormones get around and act

A
  • transported in blood by carrier proteins
  • diffuse through plasma membrane
  • alter expression of genes at level of nucleus
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8
Q

discuss water soluble hormones get around and act

A
  • easily travel in the blood (hydrophilic)
  • bind to receptors on the surface of the cell
  • results in series of of intracellular events
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9
Q

what happens when a hormone binds to its nuclear receptor

A

hormone plus receptor activates receptor, active receptor binds to DNA to turn the genes on or off
regulates transcription of specific target genes

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10
Q

what is the function of nuclear receptors

A

in the presence of their hormones, the nuclear receptor recruits additional coactivator proteins which then regulate the activation and repression of nearby target genes

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11
Q

list intracellular signal transduction pathways (water soluble)

A
  • adenyl cyclase
  • guanyl cyclase
  • phospholipase
  • tyrosine kinase
  • ion channels
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12
Q

what are the 3 components of a membrane receptor

A
  • external domain
  • transmembrane domain
  • cytoplasmic/intracellular domain
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13
Q

how does termination of hormone signalling work

A
  • once the signal is withdrawn, the response fades
  • depends on rate of destruction or removal of molecules that the signal affects
  • but the turnover rate also depends on promptness of response when a signal is turned on
  • these factors determine the half-life of the signalling molecule (T1/2)
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14
Q

what does T1/2 refer to

A
  • time taken for the concentration of a signalling molecule to fall by half
  • transient signals may have long lasting effects
  • determined by rate of synthesis and modifications of proteins
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15
Q

what are the main classes of cell surface receptors

A
  1. ion-channel linked receptors
  2. G-protein linked receptor
  3. tyrosine kinase-linked receptor
  4. receptors with intrinsic enzymatic activity
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16
Q

explain how ion channel surface receptors work

A
  • signal molecule binds to receptor
  • this opens or closes the ion channel
  • ions move into the cell by diffusion
  • excitability of post-synaptic cell altered
17
Q

describe second messenger signalling

A
  • second messengers are small intracellular signalling molecules
  • generated in large numbers by receptor activation (amplification of signal)
  • rapidly diffuse away
  • pass signal on by binding to and altering behaviour of other proteins
  • exhibit different ways of passing signal on
18
Q

list functions of intracellular proteins

A
  • scaffolding (brining signal to other proteins)
  • relays
  • adaptors (bring proteins together)
  • amplifiers
  • modulators
19
Q

list key processes in cell signalling

A
  • protein phosphorylation (via protein kinases)
  • ## reversal of protein phosphorylation (via phosphoprotein phosphatase)
20
Q

what does phosphorylation alter

A
  • enzyme activity
  • protein stability
  • protein interactions
21
Q

what are the steps of G protein mediated signal transduction

A
  1. no ligand = inactive receptor
  2. binding of ligand recruits the G protein complex
  3. GTP replaces GDP (activates G protein)
22
Q

what are the 6 classes of enzyme linked receptors

A
  • receptor tyrosine kinases (phosphorylate on intracellular signalling molecules)
  • tyrosine-kinase associated receptors (associate with intracellular proteins with tyrosine kinase activity)
  • receptor-like tyrosine phosphatases (remove phosphate groups from tyrosine on intracellular proteins)
  • receptor serine/threonine kinases (phosphorylate serines or threonines on regulatory proteins)
  • receptor guanyl cyclases (catalyse production of cytosolic cGMP)
  • histidine kinase associated receptors (two component system: kinase phosphorylates itself and passes on phosphate to intracellular signalling protein)

ENI 2 (81 decks)

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