control of metabolism Flashcards

1
Q

what are the levels of regulation of cellular metabolism

A
intracellular region (cells)
intercellular region (whole body)
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2
Q

intracellular regualtion

A

aim to maintain metabolic homeostasis

match rates of metabolic pathways to availability of substrates and requirement for ATP

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3
Q

what influences intracellular regulation

A

concentration of substrates
allosteric activation and inhibition of metabolic enzymes
covalent modification of metabolic enzymes
substrate channeling

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4
Q

what leads to the Michele’s mentalis curve

A

availability of substrates

rate of metabolic reactions is dependant on availability of substrates

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5
Q

allosteric interations

A

binding of a substrate other than AS can have a postive/negative effect

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6
Q

covalent modifications

A

e.g. phosphorylation

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7
Q

substrate channeling

A

enzymes able to convert the same substrate into different products

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8
Q

gene expression

A

enzyme levels can be increased by increased synthesis, decreased degradation ect

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9
Q

intercellular regualtion

A
liver
adipose
brain 
muscle 
coodinate together to regulate the whole body
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10
Q

what is intercellular regulation mediated by

A

hormones
nervous system
substrate availability

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11
Q

hormone regulation in energy metabolism

A

insulin

glucagon

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12
Q

insulin

A

two pp chains with disulphide bridges

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13
Q

synthesis of insluin

A

preproinsulin to proinsulin to insulin
precursor has its signal sequence removed and exocytosis
C chain removed to form active form

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14
Q

secretion of insulin increased by

A

glucose
amino acids
gastrointestinal hormones

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15
Q

inhibition of insulin causes

A

fasting
stress
extreme exercise

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16
Q

effect after a reduction in insulin secretion

A

release of glucose from liver

mediated by adrenalin released by adrenal medulla

17
Q

metabolic effects of insulin

A

carbohydrate metabolism - increased glucose uptake, increased glycogen synthesis
lipid metabolims - decrease in release of fatty acids, transport of glucose to adipocytes
protein synthesis - increase in uptake of aa into cells

18
Q

insulin mechanism of action

A

insulin binds to alpha subunit, dimerise
phosphorylation of beta subunit
phosphorylation of kinase enzyme (cascade)

also causes GLUT4 to move to membrane

19
Q

insulin receptor regulation

A

after binding, receptor internalised, blocks further signalling
receptor process in lysosome, recycled to cell surface

20
Q

glucagon

A

single pp chain

synthesised from precursor peptide

21
Q

mechanism of glucagon

A

binds to receptor
stimulate second messenger system
adenylate cyclase makes cAMP, activates protein kinase A
stimulates gluceoneogenesis and production of glucose from glycogen

22
Q

glycogen metabolic effects

A

carbohydrate metabolism
- increase breakdown of glycogen and gluconeogensis
protein metabolism
increased uptake of aa by liver

23
Q

what affects glucagon secretion

A

increase- low blood glucose, increase in aa, increased adrenaline
inhibit - blood glucose, insulin

24
Q

other hormones

A

adrenaline
norepinephrine
cortisol
oppose action of insulin

25
Q

other mechanisms of regualtion

A

cell to cell contact allows signalling

gap junctions allow passing of molecules across