Glycolysis Flashcards
What is glycolysis?
Glycolysis is a ten-step metabolic pathway that converts glucose (a six-carbon sugar) into two molecules of pyruvate (a three-carbon compound), generating a small amount of ATP and NADH in the process.
Where does glycolysis occur?
This pathway occurs in the cytoplasm of the cell and is anaerobic (doesn’t require oxygen).
How is ATP generated in glycolysis? How many ATP molecules are generated per glucose?
ATP is generated via substrate-level phosphorylation in steps 7 and 10.
Glycolysis results in a net gain of 2 ATP molecules per glucose. (4 is produced in total)
What are the two phases of glycolysis regarding energy?
Energy investment phase: Steps 1-5 where 2 ATP molecules are consumed to prepare the glucose molecule for later energy extraction.
Energy generation phase: Steps 6-10 where In this phase, ATP and NADH are produced as glucose is split into pyruvate molecules.
What are steps 1-5 of glycolysis?
Step 1: Phosphorylation of Glucose
Step 2: Isomerization
Step 3: Phosphorylation of Fructose-6-phosphate
Step 4: Cleavage
Step 5: Isomerization of DHAP
What are steps 6-10 of glycolysis?
Step 6: Oxidation and Phosphorylation
Step 7: Substrate-Level Phosphorylation
Step 8: Isomerization
Step 9: Dehydration
Step 10: Substrate-Level Phosphorylation
What pneumonic helps with remembering the products of each step of glycolysis?
“Girls Get Fine Food, Gentlemen Dine, Boys Prefer 2-Pickup PEPperoni Pizza”
Glucose
Glucose-6-Phosphate
Fructose-6-Phosphate
Fructose-1,6-Biphosphate
Glyceraldehyde-3-phosphate (G3P)/ Dihydroxyacetone phosphate (DHAP)
1,3-Bisphosphoglycerate (1,3-BPG)
3-Phosphoglycerate
2-Phosphoglycerate
Phosphoenolpyruvate (PEP)
Pyruvate
What are the net products of glycolysis?
ATP: 2 ATP (4 ATP produced - 2 ATP consumed)
NADH: 2 NADH
Pyruvate: 2 molecules
What pneumonic helps with remembering the enzymes for each step of glycolysis?
“Helen Paints Pictures About The Grinch, Pretty People Enjoy Paintings”
Hexokinase
Phosphoglucose isomerase
Phosphofructokinase-1 (PFK-1)
Aldolase
Triose phosphate isomerase
G3P dehydrogenase
Phosphoglycerate kinase
Phosphoglycerate mutase
Enolase
Pyruvate kinase
What are the three control points for the glycolysis reaction?
Step 1
Step 3 (Major control point due to its rate limiting factor)
Step 10
Why is the regeneration of NAD+ via fermentation crucial to anaerobic oxidation?
Fermentation is crucial because it regenerates NAD+ from NADH, ensuring that glycolysis can continue to produce ATP under anaerobic conditions. (NAD+ is crucial for step 6 in glycolysis)
What happens during steps 1-5 of glycolysis?
Step 1: A phosphate group is transferred from ATP to glucose.
Step 2: The six-membered ring structure of glucose is converted into a five-membered ring of fructose.
Step 3: Another ATP donates a phosphate group, resulting in a doubly phosphorylated molecule.
Step 4: The six-carbon sugar is cleaved into two three-carbon molecules: DHAP and G3P.
Step 5: DHAP is converted to G3P
What happens during steps 6-10 of glycolysis?
Step 6: G3P is oxidized, and a high-energy phosphate bond is formed. NAD⁺ is reduced to NADH.
Step 7: A phosphate group is transferred from 1,3-BPG to ADP, forming ATP.
Step 8: A phosphate group is shifted from the 3rd to the 2nd carbon.
Step 9: A water molecule is removed, forming PEP
Step 10: PEP donates its phosphate to ADP, forming ATP.
What are the possible fates of pyruvate?
Most pyruvate forms Acetyl CoA (Aerobic)
It can also form lactate in animals and ethanol in yeast and bacteria (Anaerobic)
