Chapter 17: Glycolysis

Anaerobic glycolysis

Conversion of pyruvate to lactate

Glycolysis

Conversion of glucose to pyruvate

Aerobic metabolism

Oxidation of pyruvate leads to the TCA Cycle

Anaerobic alcoholic fermentation

Pyruvate decarboxylated to acetaldehyde, which is reduced to ethanol

Glucose to glyceraldehyde-3-phosphate

Energy Investment Phase involves the conversion of _____ to _____

Hexokinase; Phosphorylation

Enzyme and Reaction: Glucose → Glucose-6-phopshate

Endergonic

Phosphorylation is (exergonic/endergonic)

Glucose phosphate isomerase; Isomerization

Enzyme and Reaction: G6P → Fructose-6-phosphate (F6P)

Phosphofructokinase; Phosphorylation

Enzyme and Reaction: F6P → Fructose-1,6-bisphosphate

Aldolase; Cleavage

Enzyme and Reaction: F-1,6-BP → DHAP + G3P

Triosephosphate isomerase; Isomerization

Enzyme and Reaction: DHAP → G3P

G3P dehydrogenase; Oxidation and phosphorylation

Enzyme and Reaction: G3P → 1,3-bisphosphoglycerate

Phosphoglycerate kinase; Transfer of a phosphate group

Enzyme and Reaction: 1,3-bisphosphoglycerate → 3-phosphoglycerate

Phosphoglyceromutase; Isomerization

Enzyme and Reaction: 3-phosphoglycerate → 2-phosphoglycerate

Enolase; Dehydration

Enzyme and Reaction: 2-phosphoglycerate → Phosphoenolpyruvate

Pyruvate kinase; Transfer of a phosphate group

Enzyme and Reaction: Phosphoenolpyruvate (PEP) → Pyruvate

2 ATP

How many ATP molecules are invested in the energy investment phase>

Hexokinase, Phosphofructokinase

Enzymes that catalyze phosphorylation reactions (driven by the hydrolysis of ATP to ADP)

• involved in ATP investment in the energy investment phase

Glyceraldehyde-3-phosphate to pyruvate

Energy Payoff Phase involves the conversion of _____ to _____

4 ATP

How many ATP molecules are produced in the energy payoff phase?

2 ATP

Net number of ATP molecules produced for every 1 molecule of glucose

Phosphoglycerate kinase, Pyruvate kinase

Enzymes involved in ATP production in the energy payoff phase

Reduction of pyruvate to lactate

Under anaerobic conditions, the most important pathway for the regeneration of NAD⁺ is _____

Lactate dehydrogenase (LDH)

NADH-linked dehydrogenase: catalyzes pyruvate → lactate

Heart muscle

H4 subunit of LDH

Skeletal muscle

M4 subunit of LDH

Pyruvate decarboxylase

Catalyzes decarboxylation of pyruvate → acetaldehyde

Alcohol dehydrogenase

Catalyzes reduction of acetaldehyde → ethanol

Exergonic

Glycolysis is (exergonic/endergonic)

-74.0 kJ/mol

∆Gº’ from glucose to 2 pyruvates is = _____

Steps 1, 3, 10

Control points in glycolysis

Hexokinase, Phosphofructokinase, Pyruvate kinase

Enzymes in the control points of glycolysis

Fructose-1,6-bisphosphate

Key intermediate in glycolysis

ATP and alanine

Inhibitors of pyruvate kinase (PK)

Alanine

Amino version of pyruvate

Transaminase

Alanine can become pyruvate through the enzyme _____

Fructose-1,6-bisphosphate

Allosterically activates pyruvate kinase so the incoming products of the first reactions of glycolysis can be processed

Less active form

Phosphorylated form is _____

Blood glucose

If _____ is low, PK is phosphorylated + glycolysis will not occur

ATP

If _____ is low, glycolysis will occur

Gluconeogenesis

Pyruvate → glucose

Insulin

Control the level of glucose in the bloodstream, activating and deactivating metabolic pathways as needed

Glycogen

Storage form of glucose