Respiration The release of energy from food (usually glucose) using enzymes There are two forms of respiration- aerobic (requiring oxygen) and anaerobic (does not require oxygen)

Aerobic Respiration Requires oxygen C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O kj energy Relatively efficient About 40% of the energy in glucose is converted to ATP. The high efficiency is due to the fact that glucose is completely broken down. Aerobic respiration begins in the cytoplasm, but most of the energy is produced by reactions that take place in the mitochondria.

Anaerobic Respiration Otherwise called fermentation, it occurs in the absence of oxygen Plant cells GlucoseEthanol + Carbon dioxide + 210kj Animal cells Glucoselactic acid +150kj Less efficient than aerobic respiration because glucose is not fully broken down The end products, alcohol and lactic acid can be dangerous if they build up. Fermentation is the basis of much of the biotechnology industry. Industrial fermentation is carried out in sterile vessels called bioreactors. Brewing Baking Environmental clean up.

Differences between aerobic and anaerobic respiration AerobicAnaerobic Oxygen necessaryOxygen not necessary Occurs in mitochondriaOccurs in cytoplasm Large amt of ATP madeSmall amt of ATP made Total breakdown of glucose Partial breakdown of glucose End products; carbon dioxide and water End products; carbon dioxide and lactic acid or alcohol

Biochemistry of Respiration

There are two stages involved in respiration –Glycolysis, which takes place in the cytosol and which does not require oxygen –Krebs cycle reactions and the Hydrogen (electron) transport system, take place in the mitochondria, and require oxygen

Glycolysis (Anaerobic) GLUCOSE (6C) PYRUVIC ACID (3C) 2ATP → 2ADP The energy released activates the glucose to break down to a high energy sugar which then converts to two triose sugars. TRIOSE SUGAR(3C) NAD→NADH 2 ADP→ATP Two hydrogens are removed and are picked up by NAD and are converted to NADH 2 H2OH2O H2OH2O Water formed in the Hydrogen Carrier System There is a low yield of ATP from glycolysis

The Krebs Cycle If enough oxygen is present, both the hydrogen atoms and Pyruvic acid enter a mitochondria PYRUVIC ACID (3C) ACETYL COENZYME A (2C) 2H NAD→NADH 2 CO 2 6C 5C 4C CO 2 2H NAD→NADH 2 CO 2 6H 4Hs attach to 2NAD 2H follow a different path ATP For every 2 hydrogen removed, three molecules of ATP are formed Released 2H is stored as NADH 2, and is transferred to the Hydrogen transport system, where water is made

Hydrogen (electron) Transport Systems A number of electron accepting molecules are found on the cristae of the mitochondria. Due to the large surface area, a large number of systems fit on the membranes of the cristae. NADH 2 is converted to NAD and a pair of high energy electrons and a pair of hydrogen ions are released. The electrons are passed from one carrier to the next losing energy as they move. After three steps in the process, enough energy is produced to convert 3ADP to 3ATP. The production of ATP in this process is called oxidative phosphorylation. At the end of the system, low energy electrons combine with hydrogen ions and oxygen to produce water 2 electrons + 2H + + ½ O 2 → H 2 O