Respiration

Essential Question: How are the various processes under cellular

respiration carried out?

Using Stored Energy

• This is the process of releasing the energy that is stored as glucose

• Can be done by heterotrophs or autotrophs• Glycolysis is the first stage (anaerobic) and

respiration is the second stage (aerobic)• Glycolysis takes place in the cytoplasm and

respiration in the mitochondria• The chemical equation is

– C6H12O6 + 6O2 6CO2 + 6H2O + energy

(heat)

Glucose

Glycolysis Krebs cycle

Electrontransport

Fermentation (without oxygen)

Alcohol or lactic acid

Chemical Pathways

Glycolysis

• A series of enzyme driven reactions that slowly change glucose

• The energy released is in the form of ATP and the end result of Glycolysis is pyruvic acid

• In order to start Glycolysis you need to have a little energy to jump start the system (2 ATP’s)

Glucose

To the electron transport chain

 Glycolysis

2 Pyruvic acid

Respiration

• Requires oxygen and is therefore aerobic

• Used the end product in Glycolysis as its starting point to release more energy

• Releases 34 more ATP molecules during electron transport which requires oxygen as a carrier molecule

• Releases CO2 into the atmosphere

Fermentation

• The process cells use to breakdown glucose when no oxygen is available

• Used by human cells during times of oxygen deprivation

• Also used by certain microbes

• Also used when the correct enzymes for respiration are not available

Lactic Acid Fermentation

• Process regenerates NAD so that Glycolysis can continue in the cell

• Pyruvic Acid + NADH Lactic Acid + NAD• Done in the muscles during intense exercise

because the muscles are producing ATP and using it faster than the lungs can supply them with oxygen for the process– the burning you feel in your muscles is the build up of

the acid that is the bi-product of this reaction

Glucose Pyruvic acidLactic acid

 Lactic Acid Fermentation

Alcoholic Fermentation

• Occurs with yeast and other microorganisms

• Pyruvic acid + NADH alcohol + CO2 + NAD• CO2 is used to make bread rise• The alcohol that is produced is the same alcohol

that is in beer and wine– if the alcohol is not removed from the system it will kill

the microorganisms– The buzzed feeling of being drunk is caused because

your cells are being killed by the alcohol

The Krebs Cycle

Essential Question: How does the process of the Krebs Cycle work?

Krebs Cycle

• The end result: Pyruvic acid from glycolysis is broken down

• ATP, FADH and NADH are generated• Occurs in the mitochondria• Bi-product is carbon dioxide

Electron Transport

• This converts the NADH and FADH2 to ATP

• This occurs in the inner membranes of the mitochondria

• Water is a bi-product of this reaction • Oxygen is the final acceptor molecule of the

transport chain• The ATP is created because of a hydrogen

gradient on either side of the membrane (like electron transport in photosynthesis)

Total Energy Gain

• Glycolysis produces 2 ATP

• Krebs cycle and electron transport produce 34 ATP

• This is only 38 percent of the energy available in glucose

• The remaining energy is released as heat