Cellular Respiration

Cellular Respiration How we are able to get energy from the food we eat Three stages Glycolysis Kreb’s Cycle Electron transport chain Remember the peep Similar to photosynthesis

Why do we need to breathe? Oxygen is required in cellular respiration Aerobic Anaerobic

Location of Cellular Respiration Glycolysis occurs in the cytosol Kreb’s cycle and electron transport chain occurs in the mitochondria.

Glycolysis First stage Glucose split apart and phosphorylated Without oxygen Glucose split apart and phosphorylated 3C= pyruvic acid Electron carrier NAD+ NADH 2 ATP produced

Do not need to know all the steps Do not need to know all the steps. Uses 2 ATP to phosphorylate sugar derivatives, making it easy to break down the compounds- remember it makes the compounds more stable when you phosphorylate them. Charged molecules are unable to leave the cell.

Glycolysis Advantages Net release of 2 ATP Very rapid Good for when cell’s energy demands rapidly increase

Kreb’s Cycle Also known as the Citric Acid cycle Pyruvic acid moves into mitochondria

Kreb’s Cycle Output 2 ATP per glucose molecule NADH and FADH2 CO2 Why is it called a cycle?

Electron Transport Chain This is where the electron carriers come into play Donate electrons to electron transport chain Final electron acceptor is oxygen Creates a proton gradient ATP synthase creates ATP

Step III: Oxidative Phosphorylation 2 steps Electron Transport Chain Transfer of electrons Proteins embedded in membrane Last transfer is to oxygen No ATP Chemiosmosis ATP synthase Embedded proteins alternate between oxidized and reduced states as they accept and donate electrons. Oxygen is the final acceptor in chain. Very electronegative. After picking up an electron, it also picks up a pair of hydrogen ions, forming water Notice how FADH2 comes in later on in the chain. Thus, it provides less energy that NADH does. About one third. Electron transport chain does not make ATP directly

Electron Transport End Results ~32 ATP!!!! FAD+ and NAD+ H2O

Overall Result of Cellular Respiration 36 ATP (varies) 36% of energy stored in glucose What happens to the other 64%?

Fermentation Happens in the absence of oxygen NADH passes electrons back to pyruvic acid Occurs in cytoplasm

2 Main Types Alcoholic Fermentation Lactic Acid Fermentation