Biology 12

Chapter 3 Cellular Energy • MHR 67

The entire glycolysis process, including
glycolysis I and glycolysis II, produces a net gain
of two ATP molecules. The energy stored in these
ATP can now be used for cellular respiration in
mitochondria.

Two ATP molecules are used in the first

phase of glycolysis to activate glucose.

A

The six-carbon molecule is split to form

two molecules of PGAL (glyceraldehyde-

3-phosphate).

B

Oxidation and phosphorylation of PGAL

results in the formation of two NADH

and two molecules of PGAP

(1,3-bisphosphoglycerate).

C

Phosphorylation removes a phosphate

group from each PGAL and produces two

molecules of ATP and two molecules of

PGA (3-phosphoglycerate).

D

Oxidation of each PGA molecule removes

water and forms two molecules of PEP

(phosphoenolpyruvate).

E

Phosphorylation removes a phosphate

group from each PEP molecule to form

two molecules of ATP and two molecules

of pyruvate.

F

ADP

P

+2 ATP

−2 ATP

+2 ATP

2 ATP

(net gain)

pyruvate pyruvate

ATP ATP

ADP

ATP ATP

ADP

ADP

NADH NADH

glucose

PGAL

P P

P

PGAP

PP

PGAL

P

PGAP

PP

PEP PEP

P

PGA

PP

PGA

ATP ATP

ADP ADP

+2 NADH

C 6

C 6

C 3

NAD+ NAD+

C 3

C 3 C 3

C 3 C 3

C 3 C 3

C 3 C 3

H 2 O H 2 O

Pi Pi

Figure 3.6Glycolysis including glycolysis I and glycolysis II, starts with one
molecule of glucose and produces two pyruvate molecules. There is a net
gain of two NADH and two ATP molecules from glycolysis.