Cellular Energy

Cellular Respiration

Cellular Energy

Energy (from breaking down food) is trapped temporarily in ATP

Oxygen makes production of ATP more efficient

• Aerobic (aero = with air) reaction

• ATP is produced in the presence of oxygen

Sometimes ATP can be produced without oxygen• Anaerobic (an = not or non, aero = with air) reaction

• ATP is produced WITHOUT the presence of oxygen

Cellular Respiration

The two stages of cellular respiration are:

1. Glycolysis- Glucose (simple sugar) is broken down into 2 pyruvates and small amount ATP and NADH

2. Kreb’s Cycle- Pyruvate & NADH are used to make more ATP. Electrons are donated to make an even more ATP

C6H12O6 + 6O2 6CO2+ 6H20 + 38ATP

Glycolysis – Breaking Down Glucose

Glycolysis [glyco=carbohydrate (sugar), -lysis=to break)• 1st stage of cellular respiration

• Anaerobic process

Enzymes in mouths and stomachs break large carbohydrates (ex. Starch) into glucose

Glucose is used in the cytoplasm to fuel Glycolysis

Glycolysis Occurs in the cytoplasm of cells

• Glucose is converted into pyruvate producing a small amount of ATP.

• (Remember glucose is an energy source.)

• If there is not enough glucose for glycolysis, then lipids can be used. (ex. fats = energy storage)

• This is what happens when we diet.

Cellular Respiration Under Aerobic Conditions

Aerobic RespirationKrebs Cycle: Occurs in mitochondria -Pyruvate produced by

glycolysis enters a mitochondria & gets converted to Acetyl-CoA

-Acetyl-CoA starts Krebs cycle to produce ATP & NADH.

Cellular Respiration Under Anaerobic Conditions

If oxygen is not available for respiration, fermentation occurs• Fermentation- recycling of energy (as NAD+)

without the presence of oxygen

• Krebs cycle can’t happenTwo types of Fermentation:

• Lactic Acid

• Alcohol

Fermentation: Lactic Acid

Lactic Acid Fermentation• During glycolysis pyruvate is

converted to Lactic Acid instead of Acetyl-CoA

• This lactic acid can build up in muscle cells causing muscle soreness

Fermentation: Alcohol Fermentation

Alcoholic Fermentation• During glycolysis pyruvate is

converted to ethanol (alcohol)

• Yeast releases ethanol and carbon dioxide as waste during fermentation•The carbon dioxide causes bread to

rise and carbonation of beer

•Ethanol causes the intoxicating effects of alcoholic beverages.

Electron Transport Chain: Review During AEROBIC respiration energy donated by

the Krebs cycle fuels the electron transport chain (ETC)

For a small amount of energy put into the chain, the ETC produces a massive amount of ATP.

Cellular Respiration Wrap-Up

Photosynthesis vs. Respiration The products for photosynthesis are the materials for

cellular respiration and visa versa• Photosynthesis starts of with carbon dioxide, water and

energy and ends with the production of sugar and water• Cellular respiration starts of with sugar and oxygen and

ends with the production of carbon dioxide, water and energy.

Energy

Photosynthesis Respiration

Light Capture Calvin Cycle ETC Glycolysis Krebs Cycle ETC Fermentation

Is stored Is Harvested