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Cell Bio > Glucose metabolism & cellular respiration > Flashcards

Glucose metabolism & cellular respiration Flashcards

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1
Q

in the presence of oxygen, glycolysis is the first step of cellular respiration. T or F.

A

T

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2
Q

Glycolysis is also known as?

A

The Embden-Meyerhof-Parnas (EMP) pathway
note: has 10 steps

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3
Q

rate limiting step/ committed step of glycolysis?

A

Reaction 3: phosphorylation
PFK-1 catalyses the reaction- fructose-6-phosphate to fructose 1,6-biphosphate

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4
Q

what is glycolysis (simple)?

A

1 glucose → 2 pyruvate + 2 ATP + 2 NADH
(takes place in the cytoplasm in eukaryotes)

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5
Q

what regulates glycolysis?

A

3 irreversible steps
- step 1: hexokinase (phosphorylation)
- step 3: PFK 1 (phosphorylation)
- step 10: pyruvate kinase (substrate-level phosphorylation)

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6
Q

what are the 3 steps of cellular respiration?

A
  • glycolysis (in cytosol)/anaerobic
  • citric acid cycle (in mitochondrial matrix)/aerobic
  • electron transport chain (inner mitochondrial matrix)/aerobic
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7
Q

if glycogen stores are depleted then liver cells will synthesise glucose by what?

A

gluconeogenesis
note: liver can replenish blood glucose levels through gluconeogenesis

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8
Q

Gluconeogensis is what?

A

the synthesis of glucose from non-carbohydrate precursors

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9
Q

what is the importance of glycogen?

A

maintain blood glucose levels

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10
Q

what are the major sites that store glycogen?

A
  • liver (10% of weight)
  • skeletal muscle (2%)
    note: glycogen is stored in cytosolic granules in vertebraes
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11
Q

whats the key molecule in glycogen synthesis?

A

UDP-glucose (glucose 1-phosphate + UTP)

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12
Q

What is the pentose phosphate pathway?

A
  • alternative route for the metabolism of glucose (it’s a shunt) which takes place in the cytosol
  • glucose 6-phosphate is metabolised and net result is 2 NADPH and 1 ribose-5-phosphate
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13
Q

what happens when the citric acid cycle is deficient in oxaloacetate or any other intermediates?

A

pyruvate is carboxylated to produce more oxaloacetate (anaplerotic reaction)

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14
Q

what happens in the krebs cycle? simple

A

acetyl groups are fed into the citric acid cycle, which enzymatically oxidizes them to CO2. The energy released is conserved in the reduced electron carriers NADH and FADH2

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15
Q

what happens in the electron transport chain? simple

A

reduced co-factors are oxidized (giving up protons (H+) and electrons). The electrons are transferred along a chain of electron-carrying molecules (electron transport chain) to O2, which they reduce to form H2O
note: oxidative phosphorylation

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16
Q

Most of the electrons entering the mitochondrial respiratory chain arise from the action of dehydrogenases that collect electrons from the oxidative reactions of ?

A
  • the pyruvate dehydrogenase complex,
  • the citric acid cycle,
  • the β-Oxidation pathway,
  • oxidative steps of amino acid catabolism
17
Q

what are the main functions of the ETC?

A
  • regenerates electron carriers: The oxidized forms of these electron carriers (NAD+ & FAD) are reused in glycolysis and the citric acid cycle
  • builds a proton gradient: across the inner mitochondrial membrane; this gradient represents a stored form of energy which is used to make ATP.
18
Q

whats chemiosmosis?

A

process in which energy from a proton gradient is used to make ATP

19
Q

which process produces most of the ATP made in cells?

A

oxidative phosphorylation

20
Q

concentrations of ATP and ADP control the rates of?

A
  • electron transfer
  • oxidative phosphorylation
  • TCA cycle
  • pyruvate oxidation
  • glycolysis
    note: high levels of ATP will decrease everything while low levels of ATP will increase everything
21
Q

ATP is an allosteric inhibitor of which enzymes?

A

phosphofructokinase-1 and pyruvate dehydrogenase

22
Q

what are the four complexes of the ETC?

A
  • NADH dehydrogenase
  • succinate dehydrogenase
  • cytochrome c reductase
  • cytochrome oxidase
23
Q

how many electrons are needed to reduce each molecule of O2?

A

4 baby!!!

24
Q

What is the cori cycle?

A

the process where glucose is converted to lactate (glycolysis) in the active muscle then in the liver this lactate is re-converted to glucose (glucogenesis).

25
Q

What is glycogenolysis?

A

breaking down glycogen to get glucose-6-phosphate (this is central metabolite- can undergo glycolysis, PPP, be converted to free glucose)

26
Q

What is glycogenesis?

A

formation of glycogen from glucose (storing glucose as glycogen)

27
Q

What are the 5 types of glycogen storage diseases?

A
  • type 1: Von Gierke disease
  • type 2: Pompe’s disease
  • type 3: Cori’s or Forbe disease
  • type 4: Andersen’s disease
  • type 5: Mcardle’s disease
28
Q

What reactions are involved in glycogen synthesis?

A
  • formation of primer by glycogenin
  • addition of glycosyl residues by glycogen synthase
29
Q

Glycogen synthase is inactivated by?

A

phosphorylation

30
Q

Glucose 6 phosphatase is only present where?

A

liver (mostly) and kidney

31
Q

What are the functions of the pentose phosphate pathway?

A
  • NADPH is used for fatty acid synthesis
  • ribose-5-phosphate is used for nucleotide and nucleic acid synthesis
  • converts glucose 6-phosphate to fructose 6-phosphate and glyceraldehyde 3-phosphate
  • maintains reduced glutathione for antioxidant activity (needed to maintain the integrity of the red blood cell membrane)
32
Q

The cytoplasmic concentration of NADP+ plays a role in determining the fate of glucose-6-phosphate. T or F.

A

T- i think if u don’t have enough NADP+, G6P will go thru the PPP

33
Q

What is the oxidative phase of the PPP?

A
  • produces NADP
  • irreversible
34
Q

What is the non-oxidative phase of the PPP?

A
  • produces ribose-5-phosphate
  • reversible reactions feed into glycolysis
35
Q

Whats the regulation of the PPP?

A
  • Glucose 6 phosphate dehydrogenase
  • when NADPH/NADP+ ratio is high- the enzyme is inhibited
36
Q

How is pyruvate converted to acetyl CoA before entering the Krebs cycle/

A

by pyruvate dehydrogenase complex in the mitochondria

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