Cellular Respiration

Cellular Respiration Definition: the creation of energy in the form of ATP from organic (usually glucose) molecules Simplified, cellular respiration is C6H12O6 (aq) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) + 36 ATP (eukaryotic cells) ΔG = -2880 kJ per mole of C6H12O6

Steps in Cellular Respiration Three steps make up the process of cellular respiration: Glycolysis, which occurs in the cytosol Kreb’s Cycle (or citric acid cycle) in the mitochondria Oxidative Phosphorylation (electron transport chain), also in the mitochondria

Glycolysis Animation What you need to know: Occurs in the Cytosol (cytoplasm) Breaks up glucose into pyruvate Yields 2 ATP molecules This would be fermentation (anaerobic respiration) 5. Forms NADH to move to next step

Kreb’s (or citric acid) Cycle Animation What you need to know: Occurs in the mitochondria CoEnzyme A facilitates beginning of this cycle 3. Releases CO2 Yields 2 ATP Molecules Yields NADH and FADH2 5. Breaking and formation of bonds releases energy

Oxidative Phosphorylation Animation What you need to know: Occurs in the cristae of the mitochondria NADH carries the electrons to start the chain, NAD+ goes back to the citric acid cycle ATP Synthase transports H+ to form ATP from ADP 4. Releases H2O 5. Yields 34 ATP Molecules

How to get Energy????? Anaerobic Respiration: when only glycolysis phase is completed and 2 ATP are released. This will happen when there is a lack of oxygen (process of making alcohol) Aerobic Respiration: complete respiration in the presence of oxygen, yielding 36 ATP (some of the energy is used in the cycle) in eukaryotic cells and 38 ATP in prokaryotic cells (Bonus: Why is that??????)

Fermentation in Yeast Yeast, yes the stuff used in bread to make it rise, often undergoes fermentation reactions. How can you design an experiment to see if the amount of sugar will effect the rate of anaerobic respiration? Observe the materials in front of you and think about the products of cellular respiration to help you do this. You will need to create a graph that represents your data, but collect data as a class! You may use excel to create your graph in the formal write up this time.