BIOL124 L 3

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  • Created by: Katherine
  • Created on: 02-06-16 15:33
What is transduction:
Cascades of molecular interactions that relay signals from receptors to target molecules in cell
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Molecuels that relay a signal from receptor to response are mostly...
proteins
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What is phosphorylation?
When protein kinases transfer phosphates from ATP to protein
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Where does phosphorylation occur?
On serine, threonine residues
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What does phosphorlyation lead to?
Protein activation
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What do protein phosphatases do?
Remove phosphates from proteins - in dephosphorlyation.
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What does the phosphorylation and dephosphorlyation system act act
acts as a molecular swith - truning activities on and off . The activity of a particular pathway is therfore regulated by the ration of kinase to phosphate activity within a cell.
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What are second messengers?
Small non protein water soluble moelcules or ions that readily spread thoughout a cell by diffusion.
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What are common second messengers
Cyclic AMP and calcium ions
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What is cyclic AMP?
a widely used second messenger
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What is Adenylyl cyclase?
An enzyme in the plasma membrane that converts ATP to cAMP in response to extraceullular signal.
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Camp can be broken down by... to form...which is...
Phosphodiesterase, AMP, inactive
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What bacterium causes cholera?
Bacterium vibrio cholerae
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Where does the bacteria colonise?
The small intestine.
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How does Cholera affect G proteins?
It affects the G protein involved in regulating salt and water excretion.
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What is the process of cholera and G proteins?
It activates a G protein - the G protein is unable to hydrolyse GTP to GDP - so is switched on all the time. This leads to constant activation of adenylate cyclase and continuous camp production.
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What do the high Camp levels result in?
They activate the CFTR causing a dramatic efflux of cl- ions and water from infected cells, leading to watery diarroea.
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What are calcium ions?
Second messengers - important becuase second messengers can regulate its concentraiton.
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Under normal conditions, intraceullular calcium concentration is...
Very low
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Pathways leading to the release of calcium invovle...
iNOSITOL TRIPHOSHATE AND DIACYGLCEROL (DAG) As additional second messengers
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What is Calmodulin?
A specific calcium modulated protein. It contains 4 ca2+ binding sites.
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What does calcium binding to calmodiun do?
Induces conformational changes, allowing CaM to bind to other proteins causing inactivation or activation.
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What are the 4 aspects of fine tuning to consider?
Amplifying the signal (and the response), specificity of the response, overall efficiency of the response, enhanced by scafforlidng proteins, termination of the response.
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What are scaffolding proteins?
Large relay proteins to which other relay proteins are attached.
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What do scaffolding protein do?
Increase signal transduction eficiency by grouping together different proteins invovled in the same pathway.
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Card 2

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Molecuels that relay a signal from receptor to response are mostly...

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proteins

Card 3

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What is phosphorylation?

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Card 4

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Where does phosphorylation occur?

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Card 5

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What does phosphorlyation lead to?

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