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Chapter 9 Cellular Respiration. Starting Questions. How are the products of photosynthesis and respiration related? The products of photosynthesis are the starting materials for respiration. What kinds of organisms undergo cellular respiration?
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Chapter 9 Cellular Respiration 392 3/1/11
Starting Questions How are the products of photosynthesis and respiration related? • The products of photosynthesis are the starting materials for respiration. What kinds of organisms undergo cellular respiration? • All organisms, including photosynthetic organisms, undergo cellular respiration as long as oxygen is available. 392 3/1/11
9-1 Key Concepts • What is cellular respiration? • What happens during the process of glycolysis? • What are the two main types of fermentation? 392 3/1/11
Chemical Energy and Food • Food source: sugars such as glucose • 1 calorie = amount of energy needed to raise 1 gram of water 1 degree Celsius • 1 Calorie = 1 kilocalorie = 1000 calories • Energy is released slowly from glucose and other foods using cellular respiration. 392 3/1/11
Cellular Respiration: An Overview Section 9-1 Mitochondrion Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Krebs Cycle Electron Transport Chain Glucose Glycolysis Mitochondrion Cytoplasm 392 3/1/11
Aerobic Respiration 392 3/1/11
Chemical Pathways Section 9-1 Glucose Krebs cycle Electrontransport Glycolysis Alcohol or lactic acid Fermentation (without oxygen) 392 3/1/11
Cellular Respiration • The process that releases energy by breaking down glucose and other food molecules in the presence of oxygen • 6O2 + C6H12O6 6CO2 + 6H2O + Energy (ATP) • oxygen + glucose carbon dioxide + water + energy 392 3/1/11
Net vs. Gross • Gross amount of product made • Ex: Made $20.00 babysitting • Net amount of product made minus amount of product used • Ex: Made $15.00 babysitting • Spent $5.00 for gas to get to babysitting job • Made $20.00 babysitting • $20.00 - $5.00 = net $15.00
Glycolysis • 2 ATP molecules must be added to get the reaction started Can be considered activation energy • 4 ATP molecules are produced (4 – 2 = net gain of 2 ATP) • 2 NADH molecules are also created • NADH • Electron carrier = NAD+ (nicotinamide adenine dinucleotide) • NAD+ + H+ + 2 high energy electrons NADH • Takes electrons to other parts of respiration • Glycolysis nets 2 ATP, 2 NADH, and 2 pyruvic acids
Glycolysis Glucose 2 Pyruvic acid To the electron transport chain Glycolysis nets 2 ATP, 2 NADH, and 2 pyruvic acids
Advantages Occurs quickly Can produce 1000s of ATP in a few milliseconds Does not require oxygen Can occur w/o oxygen Disadvantages Net gain of only 2 ATP NAD+ become filled with electrons quickly Can’t make more ATP Glycolysis: Advantages vs. Disadvantages
Anaerobic Respiration = Fermentation an = “without” aerobic = “air” • Occurs afterglycolysis only if no oxygen is available • NADH from glycolysis used, turned back into NAD+ • Goes back to glycolysis • Keeps glycolysis going • Generate as many ATP as possible Important because it recycles the NAD+ molecules so that the cell can continue to make energy
Alcoholic Fermentation • In the absence of oxygen, pyruvic acid is broken down to produce alcohol and carbon dioxide • Carried out by yeasts and a few other micoorganisms • pyruvic acid + NADH → alcohol + CO2 + NAD+ • Used to make alcoholic beverages and to cause bread dough to rise
Lactic Acid Fermentation • In many cells, the pyruvic acid that accumulates due to glycolysis is converted to lactic acid. • pyruvic acid + NADH → lactic acid + NAD+ • Occurs in muscles during heavy exercise • Lactic acid buildup in muscles causes painful, burning sensation = why muscles feel sore • Prokaryotes also produce lactic acid • Used to make cheese, yogurt, buttermilk, sour cream, pickles, sauerkraut, and kimchi.
Lactic Acid Fermentation Section 9-1 Lactic acid Glucose Pyruvic acid 392 3/1/11
Glycolysis 392 3/1/11
Review Questions • 1. What is cellular respiration? What is the equation for it? • 2. What are the 3 stages of cellular respiration in order? • 3. What is glycolysis and where does it take place in a cell? What are the products of glycolysis? • 4. What are the advantages and disadvantages of glycolysis? • 5. What is anaerobic respiration and what is its purpose? • 6. Compare and contrast alcoholic fermentation with lactic acid fermentation.