Glycolysis Flashcards
(25 cards)
what is glycolysis?
a series of 10 biochemical reactions that results in the breakdown of glucose molecules to yield 2 molecules of pyruvate. it involves breaking apart a 6 carbon molecule of glucose to a 3 carbon molecule of pyruvate.
which cells in the body generate energy through glycolysis?
every cell in the body can generate energy from glycolysis.
why is glycolysis known as the emergency energy pathway?
because energy can be generated rapidly. it is the only energy pathway in cells without a mitochondria.
what is glycolysis regulated by in resting hormones?
insulin (activator) and glucagon (inhibitor).
what is the first step of glycolysis?
glucose is converted to glucose-6-phosphate via the enzyme hexokinase. this reaction requires 1 ATP.
what is the second step of glycolysis?
glucose-6-phosphate is converted to fructose-6-phosphate.
what is the third step of glycolysis?
fructose-6-phosphate is converted to fructose 1,6-bis via the enzyme phosphofructokinase. this reaction requires 1 ATP.
what is the fourth step of glycolysis?
6 carbon molecule fructose 1,6-bisphosphate is split into two 3 carbon molecules, one dihydroxyacetone-phosphate (DHAP) and one glyceraldehyde-phosphate (GAP), via the enzyme aldolase.
what is the fifth step of glycolysis?
the DHAP molecule is converted to GAP via the enzyme triode phosphate isomerase meaning there are now two GAP molecules.
what is the sixth step of glycolysis?
the two GAP molecules are converted to two 1,3 bisphosphoglycerate molecules, via the enzyme glyceraldehyde-3-phosphate-dehyrdogenase.
what is the seventh step of glycolysis?
1,3 bisphophglycerate is converted to 3-P-glycerate via the enzyme phosphoglycerate kinase. this reaction yields 1 ATP for each molecule (aka 2 ATP).
what is the eighth step of glycolysis?
3-P-glycerate s converted to 2-P-glycerate via the enzyme phosphoglycerate mutase.
what is the ninth step of glycolysis?
2-P-glycerate is converted to PEP via the enzyme enolase.
what does PEP stand for?
phosphoenolpyruvate.
what is the final step of glycolysis?
PEP is converted to pyruvate via the enzyme pyruvate kinase, this reaction yields 1 ATP for each molecule (aka 2 ATP)
what is NADH + H^+?
a co-factor generated in step 6 of glycolysis, donates a proton (H^+) to PEP to enable the formation of pyruvate.
is the final step of glycolysis reversible?
no, due to physiological conditions it is not possible to regenerate PEP from pyruvate.
what factor decides the fate of pyruvate?
whether the cell is aerobic or anaerobic.
what happens to the pyruvate if the cell is aerobic?
pyruvate enters the link reaction to form acetyl-coenzyme-A (acetyl-CoA) which enters the Tricarboxylic Acid (TCA) Cycle and the oxidative phosphorylation pathway to generate energy in the form of ATP.
what happens if the cell is in an anaerobic state?
pyruvate is converted to lactic acid which is reversible as lactic acid is then transported to the liver where it can be reconverted to glucose via the Cori cycle.
what happens in yeast under anaerobic conditions?
pyruvate is converted to acetaldehyde and carbon dioxide, and acetaldehyde is reduced to ethanol (i.e. fermentation of glucose to yield alcohol).
what is known as the emergency energy pathway?
glycolysis
what makes glycolysis special?
it is the only energy pathway in cells with no mitochondria.
what happens to glycolysis during exercise?
during severe exercise or when the PCR system has been depleted we are heavily reliant on anaerobic glycolysis to provide energy. this is because we need to resynthesize ATP and, behind PCR, glycolysis does this the quickest.
