KEY CONCEPT The overall process of cellular respiration converts sugar into ATP using oxygen.

Cellular respiration is an aerobic process with two main stages.

Cellular respiration makes ATP by breaking down sugars.

• Cellular respiration is aerobic, or requires oxygen.• Aerobic stages take place in mitochondria.

mitochondrion

animal cell

• Glycolysis must take place first.1. takes place in cytoplasm2. two ATP molecules are used to split glucose3. four ATP molecules are produced4. two molecules of electron carrier (NADH) produced5. two molecules of pyruvate produced

pyruvate(net)

– Gycolysis is an anaerobic process (does not require oxygen).– Cellular respiration is aerobic, or requires oxygen. The products of glycolysis enter

cellular respiration when oxygen is available.

• Aerobic stages take place in mitochondria.

mitochondrion

animal cell

• The first step of cellular respiration is the Krebs Cycle:1.Pyruvate molecules from

glycolysis enter2.pyruvates are broken

down inmitochondrial matrix

3. releases carbon dioxide as waste

4.makes 2 ATP and electron carriers (NADH and FADH2) that transfer energy to an electron transport chain

6H O2

6CO 2

6O 2

mitochondrionmitochondrion

matrix (area enclosedby inner membrane)

inner membrane

ATP

ATP

energy

energy from glycolysis

1

2

4

3

and

and

and

Krebs Cycle

1. takes place in inner membrane (cristae) where oxygen enters process

2. Uses NADH and FADH2 to make ATP in the mitochondrial membrane.

• The electron transport chain produces a large amount of ATP.

6H O2

6CO 2

6O 2

mitochondrionmitochondrion

matrix (area enclosedby inner membrane)

inner membrane

ATP

ATP

energy

energy from glycolysis

1

2

4

3

and

and

and

3. ATP synthase produces ATP 4. water is released as a waste product• The breakdown of one glucose molecule produces up to

36 molecules of ATP.

• Cellular respiration makes up to 38 ATP from 1 glucose (2 from glycolysis, 2 from Krebs Cycle, and 34-36 from electron transport chain).

• The equation for the overall process is:C6H12O6 + 6O2 6CO2 + 6H2O + energy

• The reactants in photosynthesis are the same as the products of cellular respiration.

Glycolysis is needed for cellular respiration.

• The products of glycolysis enter cellular respiration when oxygen is available (aerobic).– Reactants: 2 ATP, glucose– Products: 4 ATP, 2 NADH, 2 pyruvate molecules

KEY CONCEPT Fermentation allows the production of a small amount of ATP without oxygen.

Fermentation allows glycolysis to continue.

• Fermentation allows glycolysis to continue making ATP when oxygen is unavailable (anaerobic).

• Fermentation does not make ATP.

• Lactic acid fermentation occurs in muscle cells.– pyruvate and NADH enter fermentation– energy from NADH converts pyruvate into lactic acid– Occurs in muscle cells during intense exercise– Also used to make cheese and yogurt

• Alcoholic fermentation is similar to lactic acid fermentation.– glycolysis splits glucose and the products enter

fermentation– energy from NADH is used to split pyruvate into an alcohol and carbon dioxide

– NADH is changed back into NAD+

– NAD+ is recycled to glycolysis

• Fermentation is used in food production.– yogurt

– cheese

– Bread

Aerobic vs Anaerobic Cellular Respiration

Aerobic cellular respirationAerobic cellular respiration Adv: produces 36 ATP, long term energy supplyAdv: produces 36 ATP, long term energy supply Disadv: requires oxygen, slower processDisadv: requires oxygen, slower process

Anaerobic cellular respiration (fermentation)Anaerobic cellular respiration (fermentation)Adv: no oxygen, happens quickAdv: no oxygen, happens quickDisadv: only 2 ATP, muscle sorenessDisadv: only 2 ATP, muscle soreness