lecture 35 - receptors and cell signalling Flashcards
can the body store ATP
no
ATP must be made in the cell when :
- at the time that it is needed
- at the rate that it is needed
- by oxidising fuels
why must ATP be made
- to maintain a supply of glucose between meals
- to provide immediate fuel for increased activity
- for long periods when food intake may be inadequate
what is fat storage and what can be converted into fat storage
- triacylglycerols
- stored as fat droplets in adipose tissue
excess fat and carbohydrates from diet can be converted to stored fat
what is the synthesis of triacylglycerols stimulated by
insulin
what is the synthesis of triacylglycerols
fatty acids from chylomicrons
glycerol backbone from glucose
what does insulin bind to
insulin receptor on the cell membrane
- binds to alpha domain
what does insulin binding to insulin receptor cause and what does this activate
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
what does insulin stimulate
the reactivation of fatty acids
fatty acid > fatty acyl-CoA
how does the formation of glycerol occur from glycolysis
glycerol-3-phosphate dehydrogenase converts DHAP to glycerol-P
glycerol-P to glycerol to triacylglycerol requires several steps
what is the mobilsation of triacylglycerols
hydrolysis of TAGs
- release of free fatty acids
- release of glycerol
what is the mobilisation of of triacylglycerols stimulated and catalyzed by
stimulated by hormones : adrenaline and glucagon
catalysed by hormone sensitive : lipase
what is glycogen
branched polysaccharide
- a 1,4 and 1 1,6 glycosidic bonds
where is glycogen stored
in the liver and in muscle
when are where does glycogen synthesis occur
occurs mainly in the liver and muscle immediately after a meal
what does glycogen synthesis need
energy input = ATP and UTP
- glycogen synthase and branching enzyme
what is glycogen synthesis stimulated by
insulin
what does glycogen synthase join
a 1,4 linkages
what does the branching enzyme join
a 1,6 linkages
what is the metabolism of glycogen
degraded by glycogenolysis
what is liver glycogen released for
released as glucose into blood (for brain)
what is muscle glycogen released for
releases fuel for glycolysis within muscle cells
what is excess glucose carbon converted to and where does this mainly happen and what is it stimulated by
converted to fatty acids mainly in the liver
- stimulated by insulin
- complex energy requiring process
what is the fuel for the brain
glucose (can not use fatty acids)
what is the fuel for red blood cells
glucose (no mitochondria)
what is the fuel for the liver
mostly fatty acids (can do B oxidation)
what is the fuel for the heart
mostly fatty acids
what is the fuel for muscle (resting and marathon)
resting = mostly fatty acids
marathon = mix of fatty acids and glucose
