Harvesting Energy Biology 1-2

ATP The human body uses the energy stored in ATP for all of its activities. ATP-adenosine triphosphate. Energy stored in ATP is released when a phosphate is broken off. The released energy is used to run reactions.

Harvesting Energy The energy to make ATP comes from the breakdown of the food we eat. Fermentation-breakdown of sugar to make ATP without oxygen. Cellular respiration-breakdown of sugar to make ATP using oxygen. Most of the ATP is made in the mitochondrion.

Cellular Respiration Cellular respiration begins with glycolysis. Glycolysis is the splitting of sugar into pyruvate. Takes place in the cytosol. Makes 2 ATP and 2 pyruvates. Glucose  2 pyruvates + 2 ATP

Cellular Respiration Pyruvate enters the mitochondrion. Pyruvate is turned into acetyl CoA. Carbon dioxide (CO 2 ) is produced, too. 2 pyruvates  2 acetyl CoA + 2 CO 2

Cellular Respiration cont’d Acetyl CoA is fed into the Krebs cycle. The Krebs cycle turns acetyl CoA into NADH, FADH 2, ATP and carbon dioxide. 2 Acetyl CoA  4 CO ATP + 6 NADH + 2 FADH 2.

Cellular Respiration cont’d NADH and FADH 2 are used by electron transport chains in the mitochondrion to make 34 ATP. Oxygen (O 2 ) is used at this point and water (H 2 O) is made.

Cellular Respiration cont’d Glycolysis + the Krebs cycle + electron transport chains will make about 38 ATP per glucose used. Glucose + O 2  6CO 2 + 6H 2 O + 38 ATP.

Fermentation Fermentation does not require oxygen to produce ATP. Produces few ATP per glucose. Begins with glycolysis. Takes place in the cytosol.

Fermentation cont’d Lactic acid fermentation-pyruvate is turned into lactic acid. Done by yeast and animals when little/no O 2 is present. Alcoholic fermentation-pyruvate is turned into ethanol (alcohol) and CO 2. Done by bacteria.