Glycolysis Flashcards
Purpose of glycolysis
Universal pathway in cytoplasm of All cells to produce ATP and 3/6C intermediates
- can be aerobic or anaerobic
Anaerobic glycolysis
Pyruvate is reduced to lactate via oxidation of NADH
(Converts glucose to 2 lactate)
Very minimal ATP production (2)
ONLY pathway of ATP production in the absence of O2
Priming stage of glucolysis
Glucose -> fructose 1,6 biphosphate
Enzyme hexokinase phosphorylate glucose -> G6P
Enzyme phosphohexonse isomerase changes G6P - > F6P
Enzyme phosphofructo Kinase 1 phosphorylate F6P -> F 1,6BP
Enzymes involved in irreversible steps of glycolysis
Hexokinase
Phosphofructo kinase 1
Pyruvate kinase
- if any of these enzymes are deactivated in anyway, glycolysis DOES NOT occur
Cleavage stage of glycolysis
Enzyme aldolase cleaves F 1,6BP -> GA3P and DHAP
- triode phosphate isomerase transforms DHAP into GA3P forming 2 G3P molecules
( done because only GA3P can be used in the oxidative stage)
Aerobic glycolysis
Converts pyruvate to acetyl CoA
Large-scale ATP via oxidative phosphorylation
Molecules that can be catabolized by glycolysis pathway
Glucose, fructose, galactose and ribose
Priming intermediates
Glucose ->
G6-P ->
F6-P ->
F1,6-BP
Hexokinase or Glucokinase
HK/GK
Uses ATP to phosphorylate Glucose -> G6-P
-Irreversible reaction
Phosphofructo kinase 1 (PFK1)
Uses ATP to phosphorylate F6-P
-> F1,6-BP
- irreversible reaction
Cleavage intermediates
F1,6-BP
GA3-P
DHAP
Aldolase
Cleaves F1,6-BP into GA 3-P & DHAP
Triose phosphate isomerase
Converts DHAP into GA 3-P
- does this because DHAP is not able to be oxidized in step 3
Oxidation and ATP production intermediates
GA-3P
PEP
Pyruvate
Pyruvate Kinase
Converts PEP into pyruvate
-irreversible reaction
GA-3P produces what in glycolysis?
2 NADH
2 ATP
PEP produces what in oxidation when converted to pyruvate?
2 ATP
Net products for glycolysis
2 pyruvate
2 NADH
2 ATP
4 (produced in step 3) - 2 (consumed in step 1)
Anaerobic glycolysis net products
2 ATP
2 NAD+ (used in future glycolysis reactions)
Enzyme used in anaerobic glycolysis that reduces pyruvate to lactate
Lactate dehydrogenase
- oxidizes NADH to NAD+
Total ATP produced in aerobic glycolysis
30-32
What cells undergo anaerobic glycolysis
Cells without mitochondria
Cells experiencing hypoxia
Why cant aerobic glycolysis occur in the cytoplasm only?
NADH and NAD+ are impermeable to the inner membrane of mitochondria.
- in order to regenerate NADH molecules, two shuttle systems are used to move electrons into the mitochondrial matrix
Two different electron shuttle systems used in aerobic glycolysis
1) electrons use FADH2 as an electron carrier
2) electrons use already produced NADH as electron carriers (3-5 ATP producers)
