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Flashcards in Signalling Deck (33)
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1
Q

signalling: basic principles- transmembrane proteins, signal transduction

A
  • binding of ligand to receptor protein in cell plasma membrane -> changes intracellular portion of receptor
  • receptor: transmembrane proteins (parts both out of cell/ in cytoplasm)
  • signal from ligand binding causes phosphorylation of proteins (change shape/ function)
  • signal transduction (cascade of phosphorylation) causes one or more responses in cell, (including change in protein function/ gene transcription)
2
Q

ligand interaction: not lipid soluble

A

bind to receptors on surface of target cell

3
Q

ligand interaction: most not lipid soluble

A

bind to receptors on surface of target cell

4
Q

ligand interaction: lipid soluble

A

often bind to receptors inside target cell

5
Q

eg. adrenaline signalling

A
  • fight/flight response

acute stress response:

  • nausea, loss of appetite
  • increase energy and agitation
  • stimulated by epinephrine (adrenaline) from adrenal gland
6
Q

cAMP:

A
  • cyclic adenosine monophosphate
  • secondary messenger in cell
  • activates kinase proteins which add phosphate group to enzyme -> breaks down glycogen into glucose for energy
7
Q

release glucose from liver cell: pathway

A

adrenalin detected by adrenergic receptor - G protein dissociates - cAMP activates - kinase - breaks down glycogen - glucose - energy

8
Q

list phases of cell signalling:

A
  • reception
  • transduction
  • response
9
Q

reception:

A

ligand binds to receptor

10
Q

transduction:

A

receptor activates signal transduction molecule

- sometimes initiates signalling cascade

11
Q

response:

A
  • eg. stimulates glycogen breakdown
12
Q

list types of receptors which bound to ligands:

A
  • receptor tyrosine kinase
  • G-protein coupled receptor
  • ligand-gated ion channel
13
Q

receptor tyrosin kinase:

A
  • paired receptor

- cytoplasmic portions cross phosphorylate at tyrosine residues

14
Q

G-protein coupled receptor:

A
  • receptor coupled with G protein

- when activated activates adenylyl cyclase

15
Q

ligand-gated ion channels:

A
  • open to allow ion flow across membrane

- direct response

16
Q

ion:

A
  • charged atom/ molecule

- neither negative/positive charge can pass membrane

17
Q

mitochondria:

A
  • produce ATP
  • C6H12O6 + 6O2 –> 6CO2 + 6H2O
  • 30-32 ATP per molecule glucose
  • opposite of photosynthesis
18
Q

major reaction pathways of ATP production:

A
  • glycolysis
  • Krebs cycle (citric acid)
  • electron transport phosphorylation (chemiosmosis)
19
Q

aerobic respiration:

A
  • production of ATP dependent on oxygen
20
Q

anaerobic fermentation:

A
  • oxygen limited
  • glycotic products metabolised this way
  • independent of mitochondria
21
Q

phosphorylated:

A
  • when signalling receptors activated, cytoplasmic proteins are phosphorylated
  • phosphate group added to molecule
  • usually donated from ATP
  • protein kinase transfer phosphate
22
Q

significance: phosphorylation

A
  • frequently changes proteins confirmation and surface charge
23
Q

de-phosphorylation:

A

protein phosphotases removes phosphate from protein

24
Q

significance: phosphorylation/ de-phosphorylation

A
  • act as molecular switch, turning protein on and off
25
Q

transduction:

A
  • cascade of molecular interactions relay signals from receptors to target molecules in cell
26
Q

significance: signal transduction

A
  • multiple steps
  • can amplify signal
  • more opportunity for coordination and regulation of cellular response
27
Q

response to a signal:

A
  • regulation of one or more cellular activities
28
Q

cytoplasmic: and eg

A

output response in cytoplasm

- eg. change in enzyme’s activity

29
Q

nuclear: and eg.

A

output response in nucleus, effecting change in gene expression
- final activated molecule may function as transcription factor (binds to DNA, blocks/ enhances transcription of gene)

30
Q

list two ways cells direct changes in proteins via signal pathway:

A
  • phosphorylation

- gene regulation

31
Q

faster response:

A
  • phosphorylation quickly alters protein activity (activate/deactivate) but only affect existing proteins in cytoplasm
32
Q

slower response:

A
  • gene regulation can lead to production of new proteins/ change protein conc. in cell
  • if gene expression is down-regulated, takes some time for cell concentration of gene product (protein) to deplete
33
Q

insuline binding results:

A
  • several responses
  • most anabolic
  • stimulates synthesis and storage of carbohydrates, proteins, fatty acids