Glycolysis Flashcards
What is the basis of glycolysis?
1 glucose to 2 pyruvate, creating 2 ATP and 2 NADH
What is the first step of glycolysis?
Hexokinase phosphorylation of glucose to make Glucose 6 P, using 1 ATP
What are the steps of the 1st part of glycolysis?
Hexokinase phosphorylation of glucose making glucose 6 p (using 1 ATP), then isomerisation to fructose 6 P. Further phosphorylation by phosphofructokinase (using 1 ATP) to make fructose 1,6 P. Final step of first half is adolase cutting the fructose, making glycaldeyde 3 P and dihydroxyacetone P (the DHAP is converted to GA3P) by triose phosphate isomerase
What are the steps in the second part of glycolysis?
Each GA3P is oxidated, adding an extra P but using a NAD+ (amking an NADH). The Phosph is then removed by a kinase to make ATP and Phopshoglycerate, then isomerised again. Enolase dehydrates, and pyruvate kinase removes last Phosph, making ATP and pyruvate
What is substrate level phosphorylation? Is it the most common source of ATP in the cell?
Defined at production of ATP by direct transfer of the high energy phosphate group. This is in contrast to OxPhos. It is common but produced much less ATP than OxPhos
Why is the net results of glyco only 2 ATP?
2 ATP is being used at the start of glycolysis, to net result is 2
What are the three fates of pyruvate? What is the main purpose?
Lactate, fermentation and conversion to acetyl COA
The main purpose is to create further energy in some case, but mostly remaking NAD+ needed for glycolysis
What happens to pyruvate in fermentation? In humans?
Pyruvate to acetaldehyde, then to ethanol, making NAD+. This only really happens in yeasts-humans cannot do it
What happens to pyruvate in lactate
Pyruvate can be converted to lactate by lactate dehydrogenase (extra 2 H), which uses an NADH (making an NAD+). Lactate then builds up if only way to regenerate NAD+-creates cramps later on
Why can Lactate dehydrpgenase can be used as a diagnostic tool? What other enzyme can be used?
Well LDH is in numerous tissues but not in the blood-if the enzyme can be measured in blood, then tissue could of has lysed-could be stroke, heart attack, liver disease, injury, etc. ANother enzyme to use is creatine Kinase-elevated levels mean similar things-MI, musclukar diease extent, evaluate cause of chest pain, help find carriers of dystrophy
How do muscle sustain the ATP use?
Using creatine phosphate-creatine phosphate can be made to creatine, generating ATP, which can be used as energy - and muscles have big stores of CP
What enzyme is used to generate AcCOA? What co-enzymes are used?
The pyruvate dehydrogenase complex, which is 3 enzymes together that take pyruvate + HSCOA to AcCOA, 1CO2 and 1 NADH. The enzyme, cofactor complexes are - pyruvate decarboxylase and thiamine pyrophosphate (Vitamine B1), Lipoamide reductase transacetylase and Lipoamide, and dihydrolipoyl Dehyddrogenase and FAD+
What can be said about the 3 co-enzymes?
TPP readily loses a proton, which attacks pyruvate, creating hydroxyethyl TPP
Lipoamide has a flexible arm that helps carry the pyruvate around the complex, and its S-S can undergo reduction and oxidation
FAD is a mix bewteen a riboflavin and an Adenine, and can readily lose/gain 2e and 2 protons (FAD to FADH2)
What are the steps of pyruvate to acCOA?
step one: Pyruvate is decarobxylated by pryvruvate decarboxylase and TPP, releasing a CO2
Step 2: product oxidises and transfered to lipoamide, making acetylopamide.
then transfer COA group to make acetyl COA-released
Regenerade oxidised Lipoamide and FAD, generating 1 NADH
How about glucose metabolism in cancer?
Cancers usually rely on glycolysis and lactate use, especially in agressive strains-and overexpress GLUT1-target in cancer? tried
