Chapter 9 Cellular Respiration and Fermentation

9.1 Cellular Respiration: An Overview Do you like to run, bike, or swim? These all are good ways to exercise. When you exercise, your body uses oxygen to get energy from glucose. How does your body feel at the start of exercise, such as a long, slow run? How do you feel 1 minute into the run; 10 minutes into the run? What do you think is happening in your cells to cause the changes in how you feel? Think about running as fast as you can for 100 meters. Could you keep up this pace for a much longer distance? Explain your answer.

When you are hungry, how do you feel? Imagine you are taking a test hungry, think you will do well on the test? What’s the opposite of an autotroph?

Chemical Energy and Food What are the 4 macromolecules? Carbs, proteins, lipids, nucleic acids. Organisms get their energy from food. Calorie: Amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

Our body breaks down food molecules gradually, capturing a little bit of chemical energy at key steps.

Through cellular respiration, oxygen is used to Through cellular respiration, oxygen is used to release energy from glucose and produce ATP.

Overview of Cellular Respiration What is cellular respiration? Cellular respiration is the process that releases energy by breaking down food (glucose) in the presence of oxygen. C6H12O6 + 6 O2  6 H2O + 6 CO2 + Energy glucose oxygen water carbon ATP dioxide What would be the problem if cellular respiration occurred in just one step? Burn up all energy instead of a gradual release of energy

Stages of Cellular Respiration We have three stages of cellular respiration. 1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain

Cellular Respiration: An Overview Section 9-1 Electrons carried in NADH Pyruvic acid Electrons carried in NADH and FADH2 Glucose Krebs Cycle Glycolysis Electron Transport Chain glycolysis, Krebs cycle and electron transport chain 2 2 32 36 Total ATP

Oxygen and Energy Aerobic: “with air” Requires oxygen. Think aerobics, people who work out need more oxygen! Anaerobic: “without air” Does not require oxygen. Which process do you think gets the most ATP?

Comparing Photosynthesis and Cellular Respiration Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back. Photosynthesis release oxygen into the atmosphere, and cellular respiration uses that oxygen to release energy from food.

9.2 The Process of Cellular Respiration First step in cellular respiration Glyco / lysis – “to break glucose” Does not need oxygen to occur Where does glycolysis take place in the cell? Glycolysis occurs in the cytoplasm of the cell. Glycolysis Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid.

Glycolysis How does the cell get glycolysis going? The cell uses energy. 2 molecules of ATP are used up. What are the products of glycolysis? Pyruvate and 4 ATP molecules Glucose to two molecules of pyruvate acid

C. Glycolysis Why is there only a NET of 2 ATP molecules produced during glycolysis? 2 ATP molecules were used to start reaction

The Krebs Cycle and Electron Transport After glycolysis, we move to the Krebs Cycle. Krebs Cycle: Second stage of cellular respiration. Pyruvic acid is broken down into co2. At the end of glycolysis, how much of the chemical energy in glucose is still unused? Approx. 90% Because the final stages of cellular respiration require oxygen, they are said to be aerobic.

The Krebs Cycle and Electron Transport Where do the reactions of the Krebs cycle take place in the cell??? Mitochondrial matrix (inner most compartment of the mitochondria)

The Krebs Cycle and Electron Transport Second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions

Electron Transport Chain Where do the reactions of the electron transport chain take place in the cell??? Inner membrane of mitochondria

The Electron Transport The Electron Transport Chain series of proteins in which the high-energy electrons from the Krebs cycle are used to convert ADP into ATP

Cellular Respiration and Energy In the presence of oxygen, the cell can produce 36 ATP molecules per one glucose molecule

9.3 Fermentation Glycolysis is ALWAYS the first step in the break down of glucose. Glycolysis does not need oxygen to occur If oxygen is NOT present, glycolysis is followed by anaerobic respiration. Alcoholic Fermentation Lactic Acid Fermentation

Anaerobic Respiration: Fermentation What is fermentation? Fermentation is a process by which cells release energy in the absence of oxygen. Where does fermentation occur in the cell? Cytoplasm of the cell. Why is fermentation considered an anaerobic process? Anaerobic is process that does not require oxygen Fermentation does NOT require oxygen

Anaerobic Respiration: Fermentation Two main types of fermentation Alcohol fermentation Lactic acid fermentation

Glycolysis Alcoholic Fermentation What organisms use alcoholic fermentation Yeasts and other microorganisms use alcoholic fermentation Waste products are alcohol and carbon dioxide What happens to the small amount of alcohol produced during the baking of bread? Evaporates when bread is baked.

Glycolysis Alcoholic Fermentation How does fermentation allow the production of ATP to continue? NAD+ is looped to start the process over again.

Glycolysis Lactic Acid Fermentation Section 9-1 Glucose 2 Pyruvic acid 2 Lactic acid Lactic Acid Fermentation – Lactic acid is produced by your muscles during rapid exercise when not enough oxygen is present. Prokaryotes produce lactic acid as a waste product which is used in production of foods: yogurt, cheese, sour cream, sauerkraut, etc.

SUMMARY Glycolysis Glycolysis is ALWAYS the first step in the break down of glucose. If oxygen is NOT present, glycolysis is followed by anaerobic respiration. Alcoholic Fermentation Lactic Acid Fermentation If oxygen is present, glycolysis is followed by aerobic respiration.

Energy and Exercise For short, quick bursts of energy, the body used ATP already in muscles as well as ATP made by lactic acid fermentation. For exercise longer than about 90 seconds, cellular respiration is the only way to continue generating a supply of ATP.