glycolysis Flashcards
what is the overall equation for glycolysis?
glucose + 2Pi (fr ATP) + 2ADP + 2NAD+ → 2pyruvate + 2ATP + 2NADH+ H2O + 2H+
what are the functions of glycolysis? (3)
- generate ATP without the need for oxygen
- provide substrates for further oxidation & ATP generation
- provide intermediates for biosynthesis & regulation
where does glycolysis take place? (cell + organelle)
cytoplasm, all cells!!
explain which enzymes are upregulated in the presence of insulin (2)
high glucose/fed→ insulin release→
- upregulate PFK2→ increased fructose 2,6 biphosphate→ upregulate PFK1
- upregulate PK
→upregulate glycolysis
explain which enzymes are inhibited by glucagon (2)
low glucose/fasting→ increased glucagon→
- inhibit PFK2→ PFK1
- inhibit PK
→ downregulate glycolysis (so glucose can be used for more impt function)
explain which enzymes are inhibited by ATP or citrate
high energy state→ ATP/citrate→ don’t need so much ATP
- inhibit PFK1
- inhibit PK
→ downregulate glycolysis
explain which enzymes are upregulated by AMP
low energy state→ ATP converted to ADP→ AMP (ADP + ADP)
- upregulate PFK1
- upregulate PK
→ upregulate glycolysis→ generate more ATP
explain the pathophysiology of pyruvate kinase deficiency + compensatory mechanisms (2)
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)
what sugars can enter glycolysis? (2)
- fructose
- galactose
explain how fructose enters glycolysis
fructose→(fructokinase)→ fructose-1-phosphate →(aldolase B)→→ G3P
explain how galactose enters glycolysis
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!
what is fructosuria?
fructokinase deficiency→ fructose doesn’t break down→ accumulates and gets cleared fr urine
what is the pathophysiology of fructose intolerance?
aldolase B deficiency→ accumulation of F1P→ depletes phosphate required for glycolysis (F1P metabolism uses P) + decreases fructose entering glycolysis→ ATP depletion
what is galactosemia?
G1P uridyltransferase deficiency→ accumulation of G1P→ TOXIC!!→ cataract
explain how NAD+ can be regenerated under anaerobic conditions
pyruvate→ [lactate dehydrogenase]→ lactate
lactate dehydrogenase converts NADH→ NAD+