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CELLULAR RESPIRATION. Photosynthesis and Cellular Respiration. Cellular Respiration Cellular respiration include all metabolic pathways the break down carbohydrates and other metabolites to make ATP. Cellular respiration requires oxygen and gives off carbon dioxide.
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Cellular Respiration Cellular respiration include all metabolic pathways the break down carbohydrates and other metabolites to make ATP. Cellular respiration requires oxygen and gives off carbon dioxide. The overall equation of cellular respiration: C6H12O6 + 6O2 6CO2 + 6H2O Glucose
What organisms and cells do cellular respiration All organism do glycolysis - the first step of cellular respiration. This step is anaerobic (does not require oxygen). All organisms except anaerobic bacteria do the rest of the steps in cellular respiration like Krebs cycle and electron transport because these steps are aerobic (use oxygen)
Where does it occur in a cell? The two stages of cellular respiration occur in two different sites inside a cell. The first stage – glycolysis occurs in the cytoplasm. No oxygen is required (anerobic) The second stage (Krebs cycle and electron transport) occurs in mitochondria. Oxygen is required (aerobic).
Glycolysis Glycolysis is the breakdown of glucose to two molecules of pyruvate. The energy released during glycolysis makes 2 ATP molecules.
Investment Phase Payoff Phase
Transition Reaction Pyruvate is converted to acetyl coenzyme A and CO2 is removed. Since one glucose molecule gives two pyruvate molecules in glycolysis. The transition reaction occurs twice per glucose molecule.
Krebs Cycle A cyclical series of reactions that release CO2 and produce ATP. Krebs cycle makes 2 ATP molecules of ATP per glucose molecule.
Electron Transport System The electron transport system is a series of carriers that accept the electrons removed from glucose during glycolysis and transition reaction and Krebs cycle. The system passes the electrons from one carrier to the next until finally they are received by oxygen. Since electrons pass from a higher energy to a lower energy state, the energy released is used to make ATP. The electron transport system makes 32 to 34 ATP depending on the particular cell
Respiration in animal systems: In complex animals with circulatory systems such as ourselves: Glucose enters bloodstream from digestive system. Oxygen enter bloodstream from air in lungs. Blood carries glucose and oxygen to body tissues. Glucose and sugar enter cells where the mitochondria use them to make ATP.
Why do animals breathe? To get more oxygen and to make more ATP. In glycolysis (which does not use oxygen) cells get only 2% of the energy in glucose (make only 2 ATP). When glycolysis + aerobic respiration (Krebs cycle, electron transport system) cells get about 38% of energy in glucose (make total 36 – 38 ATP)
How do we get energy from other food All complex carbohydrates are first broken down to simple sugars and all simple sugars can go through glycolysis to make pyruvate. Proteins and fats are broken down by other pathways into smaller molecules and enter the cellular respiration pathway at various points after glycolysis.
What happens to the oxygen? Oxygen is the final electron acceptor. It picks up the low energy electrons at the end of electron transport system after ATP is formed. When protons and electrons are added to oxygen water molecules are formed.
