lecture 35 - receptors and cell signalling Flashcards

1
Q

can the body store ATP

A

no

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2
Q

ATP must be made in the cell when :

A
  • at the time that it is needed
  • at the rate that it is needed
  • by oxidising fuels
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3
Q

why must ATP be made

A
  • to maintain a supply of glucose between meals
  • to provide immediate fuel for increased activity
  • for long periods when food intake may be inadequate
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4
Q

what is fat storage and what can be converted into fat storage

A
  • triacylglycerols
  • stored as fat droplets in adipose tissue

excess fat and carbohydrates from diet can be converted to stored fat

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5
Q

what is the synthesis of triacylglycerols stimulated by

A

insulin

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6
Q

what is the synthesis of triacylglycerols

A

fatty acids from chylomicrons

glycerol backbone from glucose

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7
Q

what does insulin bind to

A

insulin receptor on the cell membrane

  • binds to alpha domain
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8
Q

what does insulin binding to insulin receptor cause and what does this activate

A

causes conformational change in b subunits = activates the kinase in the cytoplasm

kinase takes a phosphate from ATP, and attaches it to a hydroxyl group

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9
Q

what does insulin stimulate

A

the reactivation of fatty acids

fatty acid > fatty acyl-CoA

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10
Q

how does the formation of glycerol occur from glycolysis

A

glycerol-3-phosphate dehydrogenase converts DHAP to glycerol-P

glycerol-P to glycerol to triacylglycerol requires several steps

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11
Q

what is the mobilsation of triacylglycerols

A

hydrolysis of TAGs

  • release of free fatty acids
  • release of glycerol
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12
Q

what is the mobilisation of of triacylglycerols stimulated and catalyzed by

A

stimulated by hormones : adrenaline and glucagon

catalysed by hormone sensitive : lipase

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13
Q

what is glycogen

A

branched polysaccharide

  • a 1,4 and 1 1,6 glycosidic bonds
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14
Q

where is glycogen stored

A

in the liver and in muscle

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15
Q

when are where does glycogen synthesis occur

A

occurs mainly in the liver and muscle immediately after a meal

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16
Q

what does glycogen synthesis need

A

energy input = ATP and UTP

  • glycogen synthase and branching enzyme
17
Q

what is glycogen synthesis stimulated by

18
Q

what does glycogen synthase join

A

a 1,4 linkages

19
Q

what does the branching enzyme join

A

a 1,6 linkages

20
Q

what is the metabolism of glycogen

A

degraded by glycogenolysis

21
Q

what is liver glycogen released for

A

released as glucose into blood (for brain)

22
Q

what is muscle glycogen released for

A

releases fuel for glycolysis within muscle cells

23
Q

what is excess glucose carbon converted to and where does this mainly happen and what is it stimulated by

A

converted to fatty acids mainly in the liver

  • stimulated by insulin
  • complex energy requiring process
24
Q

what is the fuel for the brain

A

glucose (can not use fatty acids)

25
what is the fuel for red blood cells
glucose (no mitochondria)
26
what is the fuel for the liver
mostly fatty acids (can do B oxidation)
27
what is the fuel for the heart
mostly fatty acids
28
what is the fuel for muscle (resting and marathon)
resting = mostly fatty acids marathon = mix of fatty acids and glucose