Cellular Respiration Harvesting Chemical Energy

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8

ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATP

This is an example of chemiosmosis, the use of energy in a H+ gradient to drive cellular work

Slide 57

Fig. 9-14

INTERMEMBRANE SPACE

Rotor

H+

Stator

Internal

rod

Cata-

lytic

knob

ADP

+

P

ATP

i

MITOCHONDRIAL MATRIX

Slide 58

Fig. 9-15

EXPERIMENT

Electromagnet

RESULTS

Sample

Magnetic bead

Internal

rod

Catalytic

knob

Nickel

plate

Rotation in one direction

Rotation in opposite direction

No rotation

Sequential trials

Number of photons

detected (103)

0

20

25

30

Slide 59

Fig. 9-15a

EXPERIMENT

Sample

Magnetic bead

Internal

rod

Catalytic

knob

Nickel

plate

Electromagnet

Slide 60

Fig. 9-15b

Rotation in one direction

Rotation in opposite direction

No rotation

Sequential trials

Number of photons

detected (x 103)

30

25

20

0

RESULTS

Slide 61

The energy stored in a H+ gradient across a membrane couples the redox reactions of the electron transport chain to ATP synthesis

The H+ gradient is referred to as a proton-motive force, emphasizing its capacity to do work

Slide 62

Fig. 9-16

Protein complex

of electron

carriers

H+

H+

H+

Cyt c

Q







V

FADH2

FAD

NAD+

NADH

(carrying electrons

from food)

Electron transport chain

2 H+ + 1/2O2

H2O

ADP +

P

i

Chemiosmosis

Oxidative phosphorylation

H+

H+

ATP synthase

ATP

2

1

Slide 63

An Accounting of ATP Production by Cellular Respiration

During cellular respiration, most energy flows in this sequence:

glucose  NADH  electron transport chain  proton-motive force  ATP

About 40% of the energy in a glucose molecule is transferred to ATP during cellular respiration, making about 38 ATP

Slide 64

Fig. 9-17

Maximum per glucose:

About

36 or 38 ATP

+ 2 ATP

+ 2 ATP

+ about 32 or 34 ATP

Oxidative