Overall Photosynthesis Reaction

6CO2 + 6H2O + energy C6H12O6 + 6O2

24 C-O bonds+

12 H-O bonds

36 covalent bonds

7 C-O bonds+

5 C-C bonds+

7 C-H bonds+

5 H-O bonds+

12 O-O bonds

36 covalent bonds

Overall Respiration ReactionC6H12O6 + 6O2 6CO2 + 6H2O + energy

24 C-O bonds+

12 H-O bonds

36 covalent bonds

7 C-O bonds+

5 C-C bonds+

7 C-H bonds+

5 H-O bonds+

12 O-O bonds

36 covalent bonds

C

C

Basis of photosynthesis:Light energy is used to transform C-O and H-O bonds into C-C and H-C bonds + Energy

C

O

+ Energy

Basis of respiration:Energy is liberated by transforming C-C and C-H bonds into C-O and H-O bonds

+ +

C

C

+ +

Increased potential energy

Decreased potential energy

H

C

H

C

H

O

C

O

H

O

Energy storage compounds

Energy carrier compounds

Fig. 8-8, p. 129

products haveless energy than

reactant did

Free

ene

rgy

substrate

substrates

Progress of reaction

products havemore energy than

reactants did

A + B

C + D

Free

ene

rgy

Uphill and downhill reactions.Only the downhill reaction will go forward spontaneously.Uphill reactions require an input of free energy from some other source.

Any uphill reaction needs to be combined with a downhill reaction to provide the energy needed.

ATPATP + H2O ADP + Pi + energy ADP + Pi + energy ATP + H2O

ATP is ideally suited as energy currency1. The amount of energy released is twice as

much as is needed to drive most cellular reactions.

2. ATP does not cross the cell membrane and is short lived.

3. The third phosphate bond of ATP is weak, unstable, breaks easily.

Fig. 8-9, p. 130

Proteins can bind ATP Most proteins (enzymes) that catalyze uphill

reactions bind ATP and use its energy.

ATP

C D+

Enzyme ATP-binding domain

Enzyme ATP-binding domainATP

ADP + Pi

Fig. 8-10, p. 131

adenine

adenine

ribose

ribose ribose

nicotin-amide

ribose

nicotin-amide

+

The oxidation of nicotinamide adenine dinucleotide by oxygen

The NADH loses one H and one chemical bond between H and C, which represents two electrons. The electrons may be transferred to a series of compounds before they reach oxygen.

NADH and NADPH

• NADH is used predominantly to make ATP during respiration

• NADPH is predominantly used during photosynthesis (formation of energy storage compounds)

Respiration Chapter 9

Overall Respiration ReactionC6H12O6 + 6O2 6CO2 + 6H2O + energy

24 C-O bonds+

12 H-O bonds

36 covalent bonds

7 C-O bonds+

5 C-C bonds+

7 C-H bonds+

5 H-O bonds+

12 O-O bonds

36 covalent bonds

Fig. 9-1, p. 135

Most of the glucose in a plant is stored as starch (see section on photosynthesis). Starch is a polymer of glucose. Before glucose can be respired, it needs to be produced from starch via hydrolysis. This enzymatic process does not require any energy input and is known as digestion.

DIGESTION

Stages in the Respiration of glucose

• Glycolysis (does not require O2)

• TCA cycle

(require O2)• Electron transport chain

Fig. 9-5, p. 138

ATP2

ATP2

ATP34

(net)

2 pyruvate

2 CO2

4 CO2TCACycle

6 NADH

2 FADH2

2 NADH

2 NADH

energyInput(ATP)

Mitochondrion

Cytoplasm

Electron transport chainphosphorylation

Glycolysis

glucose

water

oxygen

Overview of respiration steps

Locations of respiration stages in the plant cell

NUCLEUS

MITOCHONDRIUM

CHLOROPLASTCHLOROPLAST

CHLOROPLAST CHLOROPLAST

MITOCHONDRIUM

MITOCHONDRIUM

MITOCHONDRIUM

CYTOSOL

Notes: 1) cytosol is the same as cytoplasm 2) not all of the plant cell structures and organelles are shown 3) Digestion is by some authors considered as part of the respiration process

Cell wall

Glycolysis

TCA cycle

Electron transport chain

Digestion

Stages in Respiration

• Glycolysis

• TCA cycle

• Electron transport chain

glucose

glucose 6-phosphate

fructose 6-phosphate

ENERGY-REQUIRINGSTEPS OF GLYCOLYSIS:

2 ATP invested

fructose 1,6-bisphosphate

Fig. 9-3a, p. 137

No need to memorize intermediates

Fig. 9-3b, p. 137

2 NADH

2 ATP

2 ATP2 ADP

ENERGY-RELEASINGSTEPS OF GLYCOLYSIS:

phosphorylation,2 ATP produced

phosphorylation,2 ATP produced

2

2 NAD+

2 Pi

dihydroxyacetonephosphate

glyceraldehyde 3-phosphate

2

2

2

2

2

1,3-bisphosphoglycerate

3-phosphoglycerate

PEP

pyruvate

(to TCA cycle)

2-phosphoglycerate

Net energy yield2 ATP

2 NADH

H2O

2 ADP

No need to memorize intermediates

Overall Glycolysis ReactionGlucose + 2 ADP + 2 Pi + 2 NAD+ 2 pyruvate + 2 ATP + 2 NADH

+ 2H+

CC

C CC

H O

C O H

H

H

OH

HO

O H

HH

O H

Glucose

H

H

C CO

CO

OH

H

HH

Pyruvate

Glucose + 2 ADP + 2 Pi + 2 NAD+ 2 pyruvate + 2 ATP + 2 NADH + 2H+

C CO

CO

OH

H

HH

Pyruvate

7 C-O bonds+

5 C-C bonds+

7 C-H bonds+

5 H-O bonds

24 covalent bonds

10 C-O bonds+

4 C-C bonds+

6 C-H bonds+

2 H-O bonds

22 covalent bonds

CC

C CC

H O

C O H

H

H

OH

HO

O H

HH

O H

Glucose

H

H

Glucose + 2 ADP + 2 Pi + 2 NAD+ 2 pyruvate + 2 ATP + 2 NADH + 2H+

C CO

CO

OH

H

HH

Pyruvate

7 C-O bonds+

5 C-C bonds+

7 C-H bonds+

5 H-O bonds

24 covalent bonds

10 C-O bonds+

4 C-C bonds+

6 C-H bonds+

2 H-O bonds

22 covalent bonds and…..

CC

C CC

H O

C O H

H

H

OH

HO

O H

HH

O H

Glucose

H

H

Fig. 8-10, p. 131

adenine

adenine

ribose

ribose ribose

nicotin-amide

ribose

nicotin-amide

+

The oxidation of nicotinamide adenine dinucleotide by oxygen

NADH loses one H and one chemical bond between H and C, which represents two electrons. The electrons may be transferred to a series of compounds before they reach oxygen (see electron transport chain).

The inverse is also possible: reduction of nicotinamide adenine dinucleotide

NAD+ can gain an electron pair (of high energy) and together with a H+ can form the C-H bond again.

2e- H+