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POM > Molecular Biology - Integration of Metabolism > Flashcards

Molecular Biology - Integration of Metabolism Flashcards

1
Q

AtherEnergy intake

A

Has to be tightly coordinated with energy expenditure ; different tissues have different environments

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2
Q

Muscles

A

Very high periods of ATP requirement and relies upon carbohydrates and fatty acid oxidation

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3
Q

How much of total body weight is muscle?

A

40%

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4
Q

Brain and nervous

A

Has a continuous ATP requirement ; cannot utilise fatty acids as a fuel source - 2% of total body weight

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5
Q

Adipose tissue

A

Long term storage site for triglycerides

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6
Q

Heart

A

1% of total body weight ; can oxidise fatty acids and carbohydrates with 10% of resting metabolic rate

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7
Q

Liver

A

2.5% of total body weight ; 20% of resting metabolic rate - main glycogen store and source of blood glucose

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8
Q

Brain

A

Requires continuous supply of glucose and brain cannot metabolise fatty acids
Ketone bodies can partially substitute for glucose

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9
Q

Too little glucose

A

Hypoglycaemia - cause faintness and coma

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10
Q

Too much glucose

A

Hyperglycaemia can cause irreversible damage

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11
Q

ATP requirements

A

Light contraction - requirement met by OxPhos
Vigorous contraction - O2 limiting factor means glycogen breakdown in muscles and lactate formation

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12
Q

Heart

A

Must beat constantly and is designed for completely aerobic metabolism and rich in mitochondria ; heart utilises free fatty acids and ketone bodies

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13
Q

Loss of O2

A

Leads to cell death and myocardial infarction ; energy demand&raquo_space;> energy supply

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14
Q

Liver

A

Wide repertoire of metalolic processes - can interconvert nutrients ; glucose storage organ (glycogen)

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15
Q

Role of liver

A

Role in lipoprotein metabolism and transport of triglycerides/cholestrol

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16
Q

Excess glucose-6-phosphate

A

Can be used to generate glycogen in liver and muscle

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17
Q

Glucose 6 phosphate another fate

A

Via PPP makes nucleotides

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18
Q

Excess acetyl-CoA

A

Makes fatty acids and cholesterol

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19
Q

Fasting =

A

Ketone bodies

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20
Q

Extreme exercise

A

Demand outweighs supply and lactate is produced

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21
Q

To avoid hypoglycaemia

A

Breakdown liver glycogen stores
Release free fatty acids from adipose tissue
Convert acetyl CoA into ketone bodies

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22
Q

If all glycogen stores are used up

A

Gluconeogenesis

23
Q

TCA Cycle

A

OAA+Acetyl -> citrate
5c = a-ketoglutarate
4c = succinylcholine-CoA
Succinate
Fumarate
L-Malate (cycle begins again)

24
Q

Gluconeogenesis is

A

Pyruvate to Glucose C6

25
When is lactate generated?
By skeletal muscle during strenuous exercise when rate of glycolysis exceeds rate of TCA cycle and electron transport chain (anaerobic respiration)
26
What does lactate do?
Taken up by the liver and used to regenerate pyruvate by lactate dehydrogenase - Cori cycle
27
Where do amino acids come from?
Diet or during starvation from breakdown of skeletal muscle
28
Where does glycerol come from?
Triglyceride hydrolysis ; glycerol backbone is used to generate DHAP
29
Pathway - gluconeogenesis
Pyruvate -> OAA -> Phosphoenol pyruvate (3C) -> G3P (+DHAP from glycerol) -> Fructose-1,6-bisphosphate -> Fructose-6-phosphate -> Glucose-6-phosphate (which creates glycogen when in excess) -> Glucose
30
Gluconeogenesis
Key steps from Pyruvate to OAA to Phosphoenolpyruvate Fructose-1,6-bisphosphate to fructose-6-phosphate G6P to Glucose KEY STEPS MUST BE BYPASSED BY NON-GLYCOLYTIC PATHWAYS
31
What is different about glycolysis and gluconeogenesis?
Overall delta G value for a straight reversal of glycolysis is +90kJ which is energetically unfavourable - SO MUST find a way to bypass those kinase driver reactions
32
How to turn energetically unfavourable process into favourable one?
6 phosphoanhydride bonds are required
33
4 extra enzymes gluconeognesis
Pyruvate to OAA (-2atp) - pyruvate carboxylase OAA to phosphoenolpyruvate (-2gtp) phosphoenolpyruvate carboxykinase Fructose-1,6-bisP to fructose-6-p ; fructose-1,6-bisphosphatase Glucose-6-p to glucose ; glucose-6-phosphatase
34
Delta g for gluconeogenesis
-38
35
Glucogenic amino acids
Used to generate glucose via glucoseneogenesis
36
Ketogenic amino acids
Used to synthesis fatty acids and ketone bodies
37
Deamination of the 20 amino acids
Gives rise to 7 amino acids OAA FUMARATE SUCCINATE SUCCINYL-COA PYRUVATE ACETYL-COA A-KETOGLUTARATE
38
Fatty acids
CANNOT be converted into glucose via gluconeogensis but can be converted into ketone bodies to be used by muscle/brain
39
When muscles contract
Demand for ATP increases so more glucose transporters Adrenaline increases rate of glycolysis in the muscle and increasing rate of gluconeogenesis in the liver/release of fatty acids from adipocytes
40
Anaerobic respiration
Lactate is produced by pyruvate (with H+ ion) in the muscle - passed into blood into liver and used in gluconeogenesis to synthesise more glucose
41
What does lactate also do?
Replenishes NAD+ levels
42
Michaelis constant
Concentration of substrate at which an enzyme functions at a half -maximal rate
43
Control of metabolic pathways - muscle
Hk I is active at very low concentrations of glucose and very sensitive to G6P inhibition
44
What does this mean in muscle?
Anaerobic conditions when rate of TCA drops and glycolysis slows ; hk1 is inhibited by accumulating levels of g6p
45
Liver HK (iV)
has a much higher km so much lower glucose affinity and less sensitive to G6P inhibition
46
gLUCOSE-6-PHOSPHATASE
Found in liver catalyses reverse reaction found in gluconeogenesis
47
Glucocorticoids
Increase synthesis of metabolic enzymes concerned with glucose availability
48
When fed
More glucose - more insulin - less glucagon Glycolysis in liver produces acetyl coA which is broken down for fat synthesis Also glycogen synthesis in muscle and liver Overall stimulation of anabolic pathways
49
Fasting states
Gluconeogenesis glycogen breakdown glucagon release fatty acid breakdown for tap production (preserves glucose for brain) adrenalin stimulates glycogen breakdown and glycolysis and lipolysis (adipose)
50
Prolonged fasting
Adipose tissue hydrolyses triglyceride to provide fatty acids TCA cycle intermediates reduced in amount to provide substrates for gluconeogenesis pROTEIN BREAKDOWN provides amino acid substrates for gluconeogenesis Ketone bodies produced from fatty acids/amino acids in liver to partially sub brain's glucose requirement
51
Type 1
failure to secrete enough insulin
52
type 2
failure to respond appropriately to insulin
53
4 complications of diabetes
Hypo/hyperglycaemia cardiovascular complications ketoacidosis
54
Atherosclerosis
Buildup of fatty acids/cholestrol

POM (12 decks)

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