Cellular Respiration Obtain energy from the degradation of sugars Uses Oxygen and produces CO2

Many steps take place in the mitochondria of cells

Complementary process to photosynthesis Will recognize many of the same molecules

Oxidation-Reduction reactions Type of reaction when an electron is

transferred from one atom or molecule to another Electron donor is reducing agent Electron acceptor is oxidizing agent The addition of electron to a molecule or atom is

called reduction

Energy is released when electrons are transferred to lower energy state molecules Electron transfer chains

Cellular Respiration Mechanisms

3 Stages Glycolysis-happens in cytosol of cell Krebs cycle-happens in matrix of mitochondria Electron transport and oxidative phophorylation-cristae

Glycolysis Means “sugar splitting”-glucose is split into

Pyruvate First step of respiration Broken into two stages

Energy investment phase-uses 2ATP Energy Payoff Phase-Yields 4 ATP +2 NADH Net of 2 ATP

Energy Investment Phase Begins with Glucose 2 ATPs are used to phosphorylate Carbons 1

and 6 Activated intermediates

Isomerase converts glucose to fructose structure Isomerase is enzyme that changes one molecule to

an isomer

Eventually yields 2 molecules of glyceraldehyde phosphate Enters energy payoff phase

Fig. 9-8

Energy investment phase

Glucose

2 ADP + 2 P 2 ATP used

formed4 ATP

Energy payoff phase

4 ADP + 4 P

2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

2 Pyruvate + 2 H2O

2 Pyruvate + 2 H2OGlucoseNet

4 ATP formed – 2 ATP used 2 ATP

2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

Energy Payoff Phase Starts with Glyceraldehyde phosphate

2 for every glucose

Enzyme adds phosphate GP while 2 NADH molecules are produces

Phosphates are eventually loss resulting in the production of 4 ATP molecules

The final product is Pyruvate Moves into Krebs cycle

Transition

Once Pyruvate enters Mitochondrion it is converted to Acetyl CoA and CO2

Acetyl CoA is the starting molecule for the Krebs cycle

Fig. 9-10

CYTOSOL MITOCHONDRION

NAD+ NADH + H+

2

1 3

Pyruvate

Transport protein

CO2Coenzyme A

Acetyl CoA

Krebs cycle

Completes the oxidation of organic molecules Takes place in matrix of mitochondria Cyclic like Calvin cycle Produces 1 ATP for each acetyl CoA

2 per glucose

Many high energy electrons are saved as 3NADH and FADH2 per cycle

Also produces 2 CO2 molecules per cycle

Fig. 9-12-8

Acetyl CoA

CoA—SH

Citrate

H2O

IsocitrateNAD+

NADH

+ H+

CO2

-Keto-glutarate

CoA—SH

CO2NAD+

NADH

+ H+SuccinylCoA

CoA—SH

P i

GTP GDP

ADP

ATP

Succinate

FAD

FADH2

Fumarate

CitricacidcycleH2O

Malate

Oxaloacetate

NADH

+H+

NAD+

1

2

3

4

5

6

7

8

Fig. 9-11

Pyruvate

NAD+

NADH

+ H+Acetyl CoA

CO2

CoA

CoA

CoA

Citricacidcycle

FADH2

FAD

CO22

3

3 NAD+

+ 3 H+

ADP + P i

ATP

NADH

Transition 2

NADH and FADH2 are used in the electron transport chain Happens in cristae of mitochondrion Uses Oxygen as ultimate electron acceptor