2. Cellular Respiration TOPIC: Making ATP (the chief energy storing molecule)

3. ESSENTIAL QUESTIONS: What is Cellular Respiration? What is needed? Where does it take place? How many stages in Cellular Respiration? What role does the Mitochondria play? How important is the ETC in this process?

4. Cellular Respiration is the process by which ALL eukaryotes obtain electrons needed from carbon compounds (such as glucose) to create ATP so cells can carry out the processes of life. Cellular Respiration requires Glucose and Oxygen. Cellular Respiration takes place in the Cytoplasm and Mitochondria of each cell. ATP =

5. EQUATION Glucose + Oxygen  Carbon Dioxide + Water + ATP (E nergy) C 6 H 12 O 6 + 6 O 2  6 CO 2 + 6 H 2 O + ATP(energy) REACTANTS  PRODUCTS

6. 3 Steps are Needed Step 1: Glycolysis (no oxygen needed) Step 2: Krebs Cycle (oxygen needed) Step 3: Electron Transport Chain

7. STEP 1: Glycolysis (“splitting of sugar”) Takes place in the Cytoplasm Does NOT need oxygen (Anaerobic Respiration) The Glucose molecule is broken down into 2 Pyruvic Acids (Pyruvates) The 2 Pyruvates are then shuttled to the mitochondria where they are converted to a molecule called Acetyl-Coenzyme A for further breakdown. Glycolysis only makes 2 ATP molecules

8. Carbon Dioxide Water 2

9. STEP 2: Krebs Cycle Takes place in the Matrix of the Mitochondria (liquidy middle) Requires Oxygen (Aerobic Respiration) The Acetyl-Coenzyme A (pyruvates) is broken down and Carbon Dioxide (CO 2 ) is produced. High energy electron carriers NADH and FADH 2 are also produced N ADH and FADH 2 transport electrons to the Electron Transport Chain (ETC) for final step. The Krebs Cycle produces ~ 4 ATP molecules.

10. Carbon Dioxide Water 2 ~4

11. STEP 3: Electron Transport Chain Takes place in the Mitochondria (Cristae – folded membrane inside) Accepts all of the electrons from NADH and FADH 2 Makes about 32 ATP molecules!!!! Releases 6 water (H 2 0)molecules (waste).

12. Carbon Dioxide Water 2 ~4 32

13. ANAEROBIC RESPIRATION (without Oxygen) - So what happens where there is not enough oxygen present (sprinting, working out above your target heart rate, being chased by a lion?) The Glucose is partially broken down in the cytoplasm into 2 pyruvic acids (pyruvates) and 2 ATP molecules are made. This is called Fermentation or Anaerobic Respiration. There are 2 types of Anaerobic Respiration or Fermentation: 1. Lactic Acid Fermentation 2. Alcoholic Fermentation

14. Eukaryotic organisms can only carry out 2 types of anaerobic respiration: Lactic Acid Fermentation. In animals cells, fermentation causes a production of Lactic Acid which causes that “burning sensation” in our muscles. This is called Lactic Acid Fermentation. When glucose is broken into the 2 pyruvates, the pyruvates accepts a hydrogen atom from NADH which produces NAD+ and Lactate (lactic acid). Alcoholic Fermentation. In yeast cells (single-celled fungi), the pyruvate is converted into acetaldehyde and finally ethanol (alcohol). This is called Alcoholic Fermentation. Anaerobic Bacteria can carry out many types of fermentation.