Central Carbon Metabolism Flashcards

1
Q

substrates of glycolysis

A
  • 6 carbon sugars
  • glucose
  • investment of 2 ATP
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2
Q

substrates of pentose phosphate

A
  • 5 carbon sugars
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3
Q

products of glycolysis

A
  • 2 pyruvate (3 carbons)
  • 2 NADH
  • 2 ATP
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4
Q

Nonreversible steps of glycolysis

A
  • Glucose to glucose-6-phosphate. 1 ATP used. Hexokinase
  • Fructose-6-phosphate to Fructose-1,6-Bisphosphate. 1 ATP used. PFK 1
  • Phosphoenol pyruvate to pyruvate. 2 ATP produced. pyruvate kinase
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5
Q

Substrates of gluconeogenesis

A
  • 2 Pyruvate (3 carbons)
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6
Q

Products of gluconeogenesis

A
  • Glucose
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7
Q

Nonreversible steps of gluconeogenesis

A
  • Pyruvate to Oxaloacetate. 2 ATP used. pyruvate carboxylase
  • Oxaloacetate to PEP. 2 GTP used. PEP carboxykinase
  • Fructose-1,6-Bisphosphate to Fructose-6-phosphate. F-1,6-Bpase
  • Glucose-6-phosphate to glucose. Glucose-6-phosphatase
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8
Q

If you try to synthesize carbs on amino acids or lipids

A
  • start with GAP and avoid expense of investing 2 ATP
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9
Q

Substrates of TCA

A
  • pyruvate (3 carbons) to acetyl-CoA (2 carbons)
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10
Q

Products of TCA

A
  • 3 CO2
  • 12 NADH
  • 3 FADH2
  • 3 GTP
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11
Q

Substrates of pentose-phosphate

A
  • Glucose-6-phosphate

- 12 NADP

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12
Q

products of pentose-phosphate

A
  • 6 CO2
  • 12 NADPH
  • 12 H+
  • Pi
  • Fructose-6-Phosphate
  • Glyceraldehyde-3-Phosphate
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13
Q

Source of the amino group of amino acids

A
  • glutamate

- done by glutamate dehydrogenase

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14
Q

Glutamate family

Precursor

A
  • Glutamine
  • Proline
  • Arginine
  • alpha-ketoglutarate (5 carbons) from TCA

(GPA)

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15
Q

Aspartate family

Precursor

A
  • Asparagine
  • Methionine
  • Threonine
  • Isoleucine (only made from pyruvate)
  • Lysine
  • Oxaloacetate (4 carbons) from TCA
    (TAMIL)
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16
Q

Serine family

Precursor

A
  • Cysteine
  • Glycine
  • 3-phosphoglycerate from glycolysis
    (Super Cool Guy)
17
Q

Pyruvate family

Precursor

A
  • Valine
  • Alanine
  • Leucine
  • from pyruvate in glycolysis
    (VAL)
18
Q

Aromatic family

Precursor

A
  • Tryptophan
  • Tyrosine
  • Phenylalanine
  • from phosphoenolpyruvate (from glycolysis) and Erythrose-4-phosphate (from pentose phosphate)
    (ATTP)
19
Q

Histidine family

Precursor

A
  • Histidine

- from ribose-5-phosphate from pentose phosphate

20
Q

Beta oxidation of fatty acids

Yields

A
  • catabolizes 2 carbons at a time
  • costs 1 ATP to prime fatty acid with CoA
  • 1 FADH
  • 1 NADH
  • 1 Acetyl-CoA
21
Q

Where glycerol from Beta oxidation enters

A
  • enters glycolysis at glycerol phosphate
22
Q

Where acetyl from Beta oxidation enters

A
  • enters TCA condensing with oxaloacetate to form citrate
23
Q

Glyoxylate cycle

A
  • many of the same steps of TCA but the CO2 yielding steps are gone
  • isocitrate cleaved to form succinate and glyoxylate instead of proceeding to alpha-ketoglutarate and succinyl-CoA
  • glyoxylate combined with another acetyl-CoA to form malate
  • two acetyl-CoA molecules have now entered the cycle, and no CO2 has been produced - oxaloacetate
  • 1 oxaloacetate used in biosynthesis. the other can be used in TCA to accept acetyl-CoA
24
Q

Glyoxylate cycle purpose

A
  • allows cells to use simple carbon compounds (2C) when glucose isn’t available to put into TCA
25
Q

Nucleotides

A
  • Carbon:
    • Glycine
    • Aspartate
      Nitrogen:
    • Glutamine
26
Q

Why use pentose phosphate?

A
  1. When the need for reducing power in the form of NADPH is greater than the need for NADH
  2. When erythrose-4-phosphate or ribose-5-phosphate are needed as a precursor for amino acids.