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Clin Sci IMS, Respiratory, Renal, Cardiovascular, Nutrition & Energy > Week 5 - Cellular Energy Metabolism > Flashcards

Week 5 - Cellular Energy Metabolism Flashcards

1
Q

What are the 11 products formed in the 10 steps during glycolysis?

A 
Glucose, 
Glucose-6-phosphate, 
Fructose-6-phosphate, 
Fructose-1,6 bisphosphate, 
Dihydroxyacetone Phosphate, 
Glyceraldehyde-3-phosphate, 
1,3 - bisphosphoglycerate ,
3-phosphoglycerate,
2-phosphoglycerate,
Phosphophenolpyruvate,
Pyruvate
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2
Q

What are the enzymes (in order 0 from steps 1-10 of glycolysis?

A
  1. Hexokinase
  2. Phosphoglucose isomerase
  3. Phosphofructokinase
  4. Aldoiase
  5. Triosephosphate isomerase
  6. Glyceraldehyde Phosphate dehydrate
  7. Phosphoglycerate kinase
  8. Phosphoglycerate mutase
  9. Enolase
  10. Pyruvate Kinase
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3
Q

Describe the steps of glycolysis

A
  1. Traps glucose in cells, destabilise structure to facilitate later reactions
  2. Converst 6 carbon ring into 5 carbon ring in prep for triode formation
  3. Further destabilisation of structure preparation for triode formation
  4. splits 5 carbon ring into 2x triode sugars
  5. isomerisation reaction as only g-3-P can proceed fro further reactions
  6. provide 2x phosphate groups for ATP synthesis in subsequent reactions
  7. substrate level phosphorylation to produce ATP
  8. Isomerism to promote formation of more unstable phosphophenol pyruvate
  9. Formation of unstable product for next reaction
  10. substrate level phosphorylation of ATP
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4
Q

What are the three key regulatory enzymes in glycolysis and why?

A
  • hexokinase
  • Phosphofructokinase
  • Pyruvate kinase
    These are non reversible enzyme reactions all involving ATP.
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5
Q

Describe the glycerin Phosphate shuffle

A
  1. Glycerin-3-phosphate is oxidised to Dihydroxyacetonphosphate - reduction of FAD to FADH2 in mitochondria
  2. Dihydroxyacetonphosphate transferred to cytosol - undergoes reverse and metabolised to glycerine-3-phosphate requiring NADH oxidised to NAD+ to maintain glycolysis
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6
Q

Describe there malate aspartate shuffle

A

1.Malate oxidised to oxaloacetate via reduction of NAD+ to NADH
2. oxaloacetate converted to aspartate then back to oxaloacetate to malate and oxidising of NADH to NAD+
This system allows passing of electrons

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7
Q

What is gluconeogenesis?

A

The formation of glucose from non-carbohydrate sources

- occurs mainly in the liver

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8
Q

What are some gluconeogenec substrates ?

A 
Amino acids (not leucine/lysine)
Lactate
Pyruvate
Gycerol
Oxaloacetate
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9
Q

Describe triglycerides in gluconeogeneis

A

free fatty acid converted to Acetyl CoA

Glycerol converted to glyceraldehyde-3-phosphate and then to fructose 1,6 bisphosphate

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10
Q

Describe Phosphoenol pyruvate formation under normal conditions

A
  • Requirement for ATP + GTP hydrolysis
  • pyruvate in mitochondria converted to oxaloacetate via pyruvate carboxylase
  • Reduced to malate by mitochondrial malate dehydrogenase and exported to cytosol using NADH
  • Cytosolic malate dehydrogenase oxidises malate to oxaloacetate regenerating NADH
  • oxaloacetate is converted to PEP via phosphenol pyruvate carboxykinase
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11
Q

Describe phosphenol pyruvate formation in stress conditions/vigorous exercise

A
  • laxctate converted to pyruvate regenerating NADH
  • Conversion of pyruvate to PEP in mitochondria
  • PEP exported to cytosol
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12
Q

Describe the cori cycle

A

Where lactate is produced by muscles, transported to the liver where it is converted back to glucose in anaerobic conditions

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13
Q

Describe glycogen formation key processes

A
  • Glucose converted to glucose-1-phosphate
  • activation of glucose via additions of UDP to G-1-P
  • Addition of UDP, glucose to glycogen molecule via 1,4 alpha link and glycogen synthase
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14
Q

What are the key enzymes in glycogen Glycogen formation

A
  • UDP glucose pyrophosphorylase
  • Glycogen synthase
  • Glycogen phosphorylase
  • Glycogen branching and debranching enzymes
  • Phosphoglucomulase
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15
Q

Describe the activation of glucose from glycogen stores

A
  • ATP used in the process to generate UTP from UDP
  • Reaction of UTP and glucose-1-phosphate produced UDP glucose and inorganic phosphate
  • Catalysed by UDP glucose pyrophosphorylase
  • ATP used in the phosphorylation of glucose to glucose 1 phosphate, traps glucose in cell
  • Every mole of glucose, 2 moles of ATP consumed
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16
Q

Describe the branching enzyme in glycogenesis

A
  • After 10 glucose have been added to glycogen alpha 1,6 branch point formed via branching enzyme
  • Enzyme breaks one alpha 1,4 binds and transfers a block of residues to an interior site in glycogen molecule
  • Reattached by 1 alpha 1,6 bond
    Branching enzyme = amyloid 1,4 to 1,6 transglycosylase
17
Q

Describe glycogen Phosphorylase

A

Breaks alpha 1,4 glycosidic bonds from non reducing end to produce glucose

18
Q

Describe steps 1 - 4 of the citrate cycle

A
  1. oxaloacetate + acetyl CoA to citrate via citrate synthase
  2. Citrate to isocitrate via Aconitase dehydration and aconite rehydration
  3. isocitrate to oxalosuccinate to alpha ketogluterate via isocitrate dehydrogenase NAD+ to NADH and decarboxylation
    METABOLIC NODAL POINT
  4. alphaketogluterate to succinylCoA via alphaketogluterate dehydrogenase complex NAD+ to NADH, decarboxylation and CoA addition
19
Q

Describe steps 5-8 of the citrate cycle

A
  1. SuccinylCoA to succinate via succinyl CoA synthase
    Phosphorylation of GDP to for GTP via succinate, GTP converted to ATP 6. Succinate to fumigate via succinate dehydrogenase FAD+ to FADH2
  2. Fumerate to malate via carbanion intermediate and Fumerase
  3. malate to oxaloacetate via malate dehydrogenase and NAD+ to NADH
20
Q

Describe the essential fatty acids

A
  • stearic acid
  • oleic acid - omega 9
  • linoleum acid - omega 6
  • alpha linoleum acid - omega 3
21
Q

Describe hormone sensitive lipase

A
  • intracellular
  • Inhibition of lipolysis
  • provides glycerol-3-phosphate from glycolysis
  • promote fat storage
22
Q

Describe fatty acid synthesis

A

Acetyl ACP + malonyl ACP

  • acyl malonyl ACP condensing enzyme condenses forming ACP and CO2
  • Beta ketoacyl ACP reductase reduces to for NADP+
  • 3hydroxyacyl ACP dehydrase forming H2O
  • Enoyl ACP reductase reduces to form NADP+
  • fatty acid chain formed and extended by two carbons , substitute this chain as acetyl ACP and chain increases in length
23
Q

Describe acetyl CoA availability

A

Citrate - oxaloacetate - malate - pyruvate - oxaloacetat - citrate with acyl CoA addition
Enzymes = ATPcitrate ligase , malate dehydrogenase, nADp+ liked malate enzyme, Pyruvate carboxylase

24
Q

Describe fatty acid activation

A

Mitochondrial process used to transport activated fatty acids across membrane
via carnatine
-Add acetyl CoA to fatty acid to activate
- Use carnatine acyl transferase system replacing CoA with carnatine group
- transported via carnatine acylcarnatine transferase into mitochondrial matrix
remove carnatine group and add CoA

25
Q

Describe the 4 steps of beta oxidation of fatty acids

A
  1. fatty acyl CoA oxidation
    Acyl CoA dehydrogenase version chain length dependent
  2. hydration of double bond
    Hydroxy on Beta carbon and hydrogen on alpha carbon catalysed by enoyl CoA hydratase
  3. oxidation of beta carbon to produce ketone group, forms NADH via 3-hydroxyacyl CoA dehydrogenase
    4.Removal of thiol - thiolysis , beta ketoacyl CoA thiolase
    lysis of alpha beta c-c bond and CoA at beta bond
    removal of 2 carbons due to CoA production
26
Q

Describe ketogenesis

A
  • Predominantly in the liver
  • depletion of oxaloacetate - backing up of citrate cycle and build up of acetyl CoA which accumulates in liver cells
  • Ketone bodies exported into periphery from cells to be converted back to acetyl CoA and utilised in ATP synthesis
27
Q

Describe the process of ketogenesis

A
  • Beta hydroxybutyrate oxidised to acetoacetate
  • acetoacetate receives CoA moiety from succinyl CoA not in liver cells
  • cleavage of acetyoacyl CoA to 2x acetyl CoA which enters citrate cycle
28
Q

Describe complex 1 and 2 in oxidative phosphorylation

A

Complex 1
- receives e- from NADH
- passed through complex to Q enzyme reducing it to QH2- coenzyme Q10
- H+ moved into inter membrane space
Complex 2
- Succinate/fumeate e=reaction
- FADH2 feeds in
- no proton pump
- e- passed to coenzyme Q10 acting as e- transporter
- Less ATP with FADH2 as no proton pumping in complex 2
- Coenzyme Q10 donates e- to complex 3

29
Q

describe complex 3 and 4 of oxidative phosphorylation

A
  • e- to cytochrome c as e- receiver
  • associated with mitochondrial membrane, acts as e- shuttle
  • cytochrome c becomes oxidised and passes e- to complex 4, limited proton pumping
  • oxygen = terminal e- acceptor producing H2O
  • ATP synthase rotates, synthesising ATP
    At each stage electron acceptor has a change in reduction potential

Clin Sci IMS, Respiratory, Renal, Cardiovascular, Nutrition & Energy (17 decks)

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