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MEH- Aboli > Energy storage- glycogen and fat > Flashcards

Energy storage- glycogen and fat Flashcards

1
Q

True or false: muscle glycogen stores can only be used for skeletal muscle itself?

A

True

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2
Q

Organisation and structure of glycogen key points (3 things)

A
  • Organised like branches
  • Branches originate from a dimer of the protein glycogenin
  • Glycogenin acts as a primer at core of structure
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3
Q

Hexokinase in glycogenesis

A

Uses glucose and ATP to make glucose-6-phosphate in liver

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4
Q

What enzyme converts (reversibly) glucose-6-phosphate to glucose-1-phosphate in glycogenesis?

A

Phosphoglucomutase

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5
Q

Formation of UDP-glucose from glucose-1-phosphate in glycogenesis (2 things)

A
  • Uses UTP and water
  • Enzyme: G1P uridylytransferase
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6
Q

How is glycogen produced at end of glycogenesis (3 things)?

A
  • It combines with UDP-glucose
  • Glycogen synthase for 1,4 bonds
  • Branching enzyme for 1,6 bonds
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7
Q

What is the product of glycogenolysis?

A

Glucose-1-phosphate

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8
Q

What enzymes are used in glycogenolysis (3 things)?

A
  • Glycogen phosphorylase (1,4)
  • De-branching enzyme (1,6)
  • Phosphoglucomutase (to G6P)
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9
Q

Key point regarding glycogenolysis

A

Different enzymes allow for simultaneous inhibition of one pathway and stimulation of another

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10
Q

Why does glycogenolysis of muscle stores not contribute to blood plasma glucose (2 things)?

A
  • Muscle lacks the enzyme glucose-6-phosphatase
  • G6P enters glycolysis for energy production
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11
Q

Regulation of liver glycogen metabolism: glycogen synthase (3 things)

A
  • Stimulates glycogen synthesis
  • Stimulated by insulin (de-phosphorylation)
  • Inhibited by glucagon & adrenaline (phosphorylation)
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12
Q

Regulation of liver glycogen metabolism: glycogen phosphorylase (3 things)

A
  • Stimulates glycogen degradation
  • Stimulated by glucagon & adrenaline (phosphorylation)
  • Inhibited by insulin (de-phosphorylation)
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13
Q

Does glucagon have effect on muscle stores?

A

No

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14
Q

Does AMP affect glycogen phosphorylase in liver?

A

No

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15
Q

Glycogen storage diseases key points (4 things)

A
  • Inherited
  • Arise from deficiency or dysfunction of enzymes
  • Excess can lead to tissue damage
  • Diminished can lead to hypoglycaemia & or exercise tolerance
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16
Q

Examples of glycogen storage diseases (2 things)

A
  • Von Glerke’s disease (G6Pase deficiency)
  • McArdle disease (muscle glycogen phosphorylase deficiency)
17
Q

Where does gluconeogenesis occur?

A

Mainly liver and to lesser extent in kidneys

18
Q

3 major precursors of gluconeogenesis

A
  • Lactate
  • Glycerol
  • Amino acids
19
Q

Cori cycle

A

Glucose from liver given to muscle and lactate from muscle given to liver to metabolise into glucose

20
Q

Key enzymes in gluconeogenesis (3 things)

A
  • PEPCK (oxaloacetate to phosphoenolpyruvate)
  • Fructose-1,6-BPase (Fructose-1,6-BP to F6P)
  • G6Pase (G6P to glucose)
21
Q

What external factors contribute to the regulation of gluconeogenesis (3 things)?

A
  • Starvation/fasting
  • Prolonged exercise
  • Stress
22
Q

Fructose-1,6-BP in regulation of gluconeogenesis (3 things)

A
  • Stimulated by glucagon & cortisol
  • Inhibited by insulin
  • Affects amount and activity
23
Q

PEPCK in regulation of gluconeogenesis (3 things)

A
  • Stimulated by glucagon & cortisol
  • Inhibited by insulin
  • Amount affected only
24
Q

When does gluconeogenesis occur?

A

Over 8-10 hrs from feeding

25
Q

Lipogenesis key points (5 things)

A
  • Mainly in liver
  • Citrate leaves (after Krebs) and converted back to acetyl~CoA & oxaloacetate in cytoplasm
  • Acetyl~CoA carboxylase produces malonyl~CoA from acetyl~CoA
  • That enzyme is a key regulator
  • Fatty acid synthase complex builds fatty acids by addition of 2 C units
26
Q

Oxaloacetate after cleavage in cytoplasm (2 things)

A
  • Converted into malate
  • Converted into pyruvate via malic enzyme: produces NADPH
27
Q

Regulation of acetyl~CoA carboxylase (2 things)

A
  • Stimulated by insulin(covalent de-phos) and citrate(allosteric)
  • Inhibited by glucagon/adrenaline(covalent phos) and AMP(allosteric)
28
Q

Hormone sensitive lipase regulation (2 things)

A
  • Glucagon & adrenaline = phosphorylation & activation
  • Insulin = de-phosphorylation & inhibition

MEH- Aboli (6 decks)

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