Respiration The energy making process that occurs continuously in all organisms The energy making process that occurs continuously in all organisms Stored chemical energy in food is transferred to a form that organisms can use Stored chemical energy in food is transferred to a form that organisms can use Exchanges of gases between organisms and their environments usually involved Exchanges of gases between organisms and their environments usually involved

Cellular Respiration C 6 H 12 O 6 + O 2 → ATP + H 2 O + CO 2 Enzyme controlled reaction that changes glucose into ATP ATP is hydrolyzed releasing energy forming ADP Takes place in the mitochondria and the reaction is reversible Cell Respiration may be aerobic or anaerobic Aerobic cellular respiration- requires the use of free oxygen atoms Anaerobic cellular respiration- oxygen is not used

In the absence of oxygen, fermentation reactions produce alcohol or lactic acid, but no additional ATP

Cellular Respiration

Three Main Stages of Respiration GLYCOLYSIS GLYCOLYSIS THE KREB CYCLE THE KREB CYCLE ELECTRON TRANSPORT ELECTRON TRANSPORT

Glycolysis The process in which 1 molecule of glucose is broken in half, producing 2 molecules of pyruvic acid. The process in which 1 molecule of glucose is broken in half, producing 2 molecules of pyruvic acid. Takes place in the cytoplasm Takes place in the cytoplasm Requires a “little” energy to get things going Requires a “little” energy to get things going 2 ATP in → 4 ATP out, 2 ATP net gain 2 ATP in → 4 ATP out, 2 ATP net gain Energy yield is small from glycolysis. The process is very fast, producing thousands of ATP in a few milliseconds. Done WITHOUT oxygen Energy yield is small from glycolysis. The process is very fast, producing thousands of ATP in a few milliseconds. Done WITHOUT oxygen

Glycolysis

The Kreb Cycle Pyruvic acid is broken down into CO 2 in a series of energy extracting reactions Pyruvic acid is broken down into CO 2 in a series of energy extracting reactions Pyruvic acid enters the mitochondria, a carbon is removed forming CO 2, electrons are removed and with the help of coenzyme A it is converted into citric acid (contains 6 Carbons) Pyruvic acid enters the mitochondria, a carbon is removed forming CO 2, electrons are removed and with the help of coenzyme A it is converted into citric acid (contains 6 Carbons)

The Krebs Cycle

Energy Extraction Citric acid is broken down into citric acid a 5 carbon Citric acid is broken down into citric acid a 5 carbon Along the way, 2 CO 2 molecules are released, as well as, electrons. Along the way, 2 CO 2 molecules are released, as well as, electrons. ONE MOLECULE OF ATP IS GENERATED! ONE MOLECULE OF ATP IS GENERATED!

Electron Transport Chain Uses high energy electrons from the Kreb cycle to convert ADP to ATP Uses high energy electrons from the Kreb cycle to convert ADP to ATP