Cellular Respiration Chapter 9

Food = source of energy A Calorie – is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. Cells don’t “burn” glucose or other foods. Instead, they gradually release the energy. The Calorie used on food labels is a kilocalorie, or 1000 calories

Feel the Burn 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, a six-carbon sugar. 1.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? 2.What do you think is happening in your cells to cause the changes in how you feel? 3.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.

Cellular Respiration The process that releases energy by breaking down glucose & other food molecules in the presence of oxygen. 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen + glucose → carbon dioxide + water + energy

Aerobic Respiration

3 Stages make up Cellular Respiration Glycolysis Kreb Cycle Electron Transport

Fermentation (without oxygen) Chemical Pathways Section 9-1 Glucose Krebs cycle Electron transport Glycolysis Alcohol or lactic acid Fermentation (without oxygen)

Figure 9–2 Cellular Respiration: An Overview Section 9-1 Mitochondrion Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Electron Transport Chain Krebs Cycle Glycolysis Mitochondrion Cytoplasm

3 Stages make up Cellular Respiration Glycolysis – process in which 1 molecule of glucose is broken in half, producing 2 molecules of pyruvic acid & gains 2 ATP molecules. O2 present - it is followed by the Kreb Cycle & the electron transport chain. O2 not present (anaerobic) - it is followed by fermentation.

To the electron transport chain Figure 9-3 Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain

Glycolysis http://highered. mcgraw-hill

Fermentation Fermentation – releases energy in food & converts NADH back into NAD+ keeping the supply of ATP constant. Alcoholic fermentation – yeasts & a few other microorganisms; causes bread dough to rise. Lactic Acid fermentation – in muscles during rapid exercise when the body can’t supply enough O2 to the tissues; without oxygen, the body isn’t able to produce the ATP required. Buildup causes pain & soreness.

Figure 9–4 Lactic Acid Fermentation Glucose Pyruvic acid

Section 9-2 Rolling and Folding Some of the steps in cellular respiration take place in the membrane inside the cell structure called the mitochondrion, which has a folded inner membrane. What purpose do these folds serve?

Electron Transport Chain Section 9-2 Flowchart Cellular Respiration Glucose (C6H1206) + Oxygen (02) Glycolysis Krebs Cycle Electron Transport Chain Carbon Dioxide (CO2) + Water (H2O)

3 Stages make up Cellular Respiration Kreb Cycle – requires O2 (aerobic) In eukaryotes. Takes place in the mitochondria. Aka. Citric acid cycle b/c it’s one of the first products. Pyruvic acid is broken down into CO2 which is released into the air. NAD+ is changed to NADH & FAD is changed to FADH2 which carry high-energy electrons to the electron transport chain.

The Krebs Cycle http://highered. mcgraw-hill

The Krebs Cycle

Figure 9–6 The Krebs Cycle Citric Acid Production Mitochondrion

3 Stages make up Cellular Respiration Electron Transport – uses high-energy electrons from the Krebs cycle to convert ADP into ATP. In eukaryotes it’s composed of carrier proteins located in the mitochondria. In prokaryotes the same chain is in the cell membrane where energy is used to move H+ ions through ATP synthase. ATP synthase – protein sphere that spins, adding a phosphate to ADP creating ATP.

The Electron Transport Chain

The Electron Transport Chain

Figure 9–7 Electron Transport Chain Hydrogen Ion Movement Channel Mitochondrion Intermembrane Space ATP synthase Inner Membrane Matrix ATP Production

Cellular Respiration Glycolysis + Krebs + Electron Transport = 36 ATP / glucose molecules.

The Human Body Contains small amounts of ATP. When the body needs energy fast, muscle cells produce ATP by Lactic Acid Fermentation. For long-term needs, the body must use cellular respiration.

Comparing Photosynthesis & Cellular Respiration Energy flows in Photosynthesis Cellular Respiration takes place in the opposite direction. Photosynthesis – removes CO2 & puts O2 back into air. Cellular Respiration – removes O2 & puts CO2 back into air.

Comparing Photosynthesis & Cellular Respiration 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy Photosynthesis 6CO2 + 6H2O + light→C6H12O6 + 6O2