glycolysis Flashcards

1
Q

what is the overall equation for glycolysis?

A

glucose + 2Pi (fr ATP) + 2ADP + 2NAD+ → 2pyruvate + 2ATP + 2NADH+ H2O + 2H+

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2
Q

what are the functions of glycolysis? (3)

A
  1. generate ATP without the need for oxygen
  2. provide substrates for further oxidation & ATP generation
  3. provide intermediates for biosynthesis & regulation
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3
Q

where does glycolysis take place? (cell + organelle)

A

cytoplasm, all cells!!

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4
Q

explain which enzymes are upregulated in the presence of insulin (2)

A

high glucose/fed→ insulin release→

  • upregulate PFK2→ increased fructose 2,6 biphosphate→ upregulate PFK1
  • upregulate PK

→upregulate glycolysis

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5
Q

explain which enzymes are inhibited by glucagon (2)

A

low glucose/fasting→ increased glucagon→

  • inhibit PFK2→ PFK1
  • inhibit PK

→ downregulate glycolysis (so glucose can be used for more impt function)

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6
Q

explain which enzymes are inhibited by ATP or citrate

A

high energy state→ ATP/citrate→ don’t need so much ATP

  • inhibit PFK1
  • inhibit PK

→ downregulate glycolysis

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7
Q

explain which enzymes are upregulated by AMP

A

low energy state→ ATP converted to ADP→ AMP (ADP + ADP)

  • upregulate PFK1
  • upregulate PK

→ upregulate glycolysis→ generate more ATP

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8
Q

explain the pathophysiology of pyruvate kinase deficiency + compensatory mechanisms (2)

A

fall in ATP→ affects cell integrity→ hemolysis→ decreased O2 delivery

compensation:
1. increased PK synthesis in liver
2. increase 2,3-BPG in RBCs to increase O2 delivery to tissues (no DNA to make more PK or mitochondria to make more ATP)

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9
Q

what sugars can enter glycolysis? (2)

A
  1. fructose
  2. galactose
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10
Q

explain how fructose enters glycolysis

A

fructose→(fructokinase)→ fructose-1-phosphate →(aldolase B)→→ G3P

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11
Q

explain how galactose enters glycolysis

A

galactose→ [galactokinase]→ galactose-1-P (+UDP glucose)→ [G1P uridyltransferase]→ glucose-1-p (+UDP-galactose)→→ glucose-6-p

UDP glucose & UDP-galactose are isomers
UDP-galactose→ UDP glucose→ glycogen synthesis!

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12
Q

what is fructosuria?

A

fructokinase deficiency→ fructose doesn’t break down→ accumulates and gets cleared fr urine

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13
Q

what is the pathophysiology of fructose intolerance?

A

aldolase B deficiency→ accumulation of F1P→ depletes phosphate required for glycolysis (F1P metabolism uses P) + decreases fructose entering glycolysis→ ATP depletion

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14
Q

what is galactosemia?

A

G1P uridyltransferase deficiency→ accumulation of G1P→ TOXIC!!→ cataract

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15
Q

explain how NAD+ can be regenerated under anaerobic conditions

A

pyruvate→ [lactate dehydrogenase]→ lactate

lactate dehydrogenase converts NADH→ NAD+

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16
Q

explain how NAD+ can be regenerated under aerobic conditions

A

oxphos in mitchondria

17
Q

what are the possible pathways of pyruvate? (5)

A
  1. pyruvate ↔ glucose (glycolysis/gluconeogenesis)
  2. pyruvate ↔ [LDH] ↔ lactic acid
  3. pyruvate → [PDH] → aceytl CoA (→TCA cycle)
  4. pyruvate → [PC] → oxaloacetate (→ TCA cycle or gluconeogenesis)
  5. pyruvate ↔ [ALT] ↔ alanine (cahill cycle)