Cellular Respiration: Glycolysis

Question 1

why is glycolysis the most ancient metabolic pathway?

Answer 1

anaerobic, eukaryotes and prokaryotes can do it, doesn’t require mitochondria, simplest pathway

Question 2

Step one of glycolysis

Answer 2

Phosphorylation: carbon 6 of the glucose molecule gets replaced with a phosphate group to create glucose-6-phosphate (1 ATP is reduced to ADP)

Question 3

Step 2 of glycolysis

Answer 3

Isomerization: the glucose-6-phosphate rearranges itself to become fructose-6-phosphate

Question 4

Step 3 of glycolysis

Answer 4

2nd phosphorylation: hydroxyl on carbon 1 is removed and replaced with phosphate group, turns into fructose-1,6-bi phosphate (1 ATP turns into ADP)

Question 5

Step 4 of glycolysis

Answer 5

Lysis: fructose-1,6-biphosphate splits into glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP)

Question 6

Step 5 of glycolysis

Answer 6

Conversion: DHAP converted to G3P (2 G3P in total now)

Question 7

Step 6 of glycolysis (start of energy payoff phase)

Answer 7

Oxidation: 2 e- and 2 p+ are removed from G3P to turn into 1,3-biphosphoglycerate (NAD+ accepts 1 e- and 1 p+ to turn into NADH, other proton released in cytosol) x2

Question 8

Step 7 of glycolysis

Answer 8

Dephosphorylation: 1 out of 2 phosphate groups on 1,3-biphosphoglycerate is transferred to ADP to become ATP (becomes 3-phosphoglycerate) x 2

Question 9

Step 8 of glycolysis

Answer 9

Phosphate transfer: 3-phosphoglycerate rearranged, phosphate group moves from C-3 to C-2 (2-phosphoglycerate)

Question 10

Step 9 of glycolysis

Answer 10

Dehydration: loss of hydroxyl + e- in 2-phophoglycerate (turns into phosphoenolpyruvate/ PEP)

Question 11

Step 10 of glycolysis

Answer 11

2nd Dephosphorylation: phosphate group removed from phosphoenolpyruvate (turns into pyruvate) (ADP turns into ATP)

Question 12

What is the end product of glycolysis?

Answer 12

2 pyruvate molecules, 2 ATP molecules, 2 NADH molecules, and 2 H+

Question 13

Net reaction of glycolysis

Answer 13

glucose + 2ADP + 2 Pi + 2 NAD+ creates 2 pyruvate + 2 ATP + 2 NADH + 2 H+

Question 14

What happens to the pyruvate molecules if O2 is present?

Answer 14

aerobic respiration occurs (pyruvate oxidation, krebs cycle, ETC)

Question 15

What happens to the pyruvate molecules if O2 is not present?

Answer 15

anaerobic respiration occurs (fermentation)