Glycolysis Flashcards
What are the four major fates for glucose in cell:
- Synthesis of structural polymers: ECM and cell wall polysaccharides
- Oxidation via pentose phosphate pathway: ribose 5-phosphate
- Storage: Glycogen, starch, sucrose
- Oxidation via glycolysis: Pyruvate
What are the products in glycolysis
- 2 pyruvate
- 2 NADH
- 2 H+
- 2 ATP
- 2 H2O
Glycolysis is divided into two reactions:
- Glucose + 2 NAD+ = 2 pyruvate + NADH + 2H+
2. 2 ADP + 2Pi = 2 ATP + 2 H2O
We always have to regenerate ___ for glycolysis to continue
NAD+
There is a net gain of how many ATPS
2
Production of ATP is:
endergonic
Glycolysis is ___under standard conditions
irreversible
Glycolysis occurs in the
cytosol
Glycolysis is anaerobic.
True
Committed steps have a lot of ___modifiers and ___inhibitors
allosteric ; feedback
Glycolysis deals with ___reactions divided into ___phases
10; 2 (5+5)
What is the first phase of glycolysis
Invest energy (from ATP) to break bonds and create two “high energy” 3 carbon compounds
What is the second phase of glycolysis
Oxidize these two compounds to pyruvate:
More energy is released in the ___phase than used in the ___first phase
second; first
What are the steps of the first (investment) phase of glycolysis
- Phosphoralate glucose via hexokinase
- Rerrangement of enzymes –>phosphohexose isomerase
- Phosphorlate again: Fructose 6 -phosphate into fructose 1,6 biphosphate via phosphofructokinsae 1. This is the committed step!
- Aldolase Cleaves fructose 1.6 bisphosphate into 2 -3 carbon phosphoralated compounds: Glyceraldehyde 3-phosphate and Dihydroxyacetone phosphate which gets rerragnged back to glyceraldehyde 3 phosphate which is the only one that continues in the cycle
What are the steps of the second (payoff) phase of glycolysis
- Glyceraldeyhe 3 phosphate gets phosphoralated via G3P dehydrogenase with inorganic phosphate to 1, 3 bisphosphate. This is the step that converts NAD+ to NADH. The enzyme that does this is a dehydrogenase!
- Taking off phosphate group via phosphoglycerate kinase (execption!) 1-3 Bisphosphoglycerate; dephosphoralate and make 1 ATP for each G3P.
- Arrange 3 phosphoglycerate to 2 phosphoglycerate via phosphoglucomutase.
- Enolase dehydrates 2 phosphoglycerate to form phosphoenolpyruvate (PEP). 5. Pyruvate kinase converts PEP to Pyruvate which generates ATP.
Make ___ATPS per glucose. But net gain of
4; 2
A negative delta G tells you
its not a reversible reaction
What are hexokinase isozymes
Hexokinase 1: main enzyme in brain and RBC; have highest affinity for glucose
Hexokinase II: Main enzyme in muscle
Hexokinase IV (Glucokinase): found in liver. Cooperatively reg. by glucose. Reaction rate is glucose limited so acts as a glucose sensor. Much higher Km.
If ADP and AMP levels are high it signals:
an increase in glycolytic pathway
Pyruvate is not the endpoint bc
we need to regenerate NAD+
What are the fates of pyruvate
- Lactate
- Acetyl CoA –>citric acid cycle
- Anabolism; oxaloacetate; alanine
- Fermentation to ethanol in yeast
Conversion to lactate is irreversible, but it can be reversible if you
take away product
What is the Cori cycle
Under anaerobic conditions we convert glucose into lactate which diffuses into bloodstream taken up by liver and used as a starting point for gluconeogenesis using lactate as its starting point during recovery send glucose back into bloodstream where it gets taken up by skeletal muscle and reconverted into glycogen.
