Chptr 9: Cellular Respiration & Fermentation

1. Chptr 9: Cellular Respiration & Fermentation

2. 9.1: Cellular Respiration: an Overview • Key Questions • Where do organisms get energy? • What is cellular Respiration? • What is the relationship between photosynthesis and cellular respiration • Vocab: • Calorie • Cellular Respiration • Aerobic • Anaerobic

3. Where do we get energy? • Autotrophs vs. Heterotrophs Autotroph: Makes own food through Photosynthesis Heterotroph: rely on other organisms for food

4. Why is food good? how much energy is stored in food? • When we digest food…we are breaking the chemical bonds with the molecules = Calories! • Calorie is the measure of energy within food • Technically: A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree celsius. • On labels, the Cal # is a kilocalorie / 1000calories • All macromolecules can be used for fuels! • However, the value depends on its structure (pg 45-48) • 1 gram of glucose= 3811 calories of heat (3.8 C) • 1 gram of beef fat = 8893 calories of heat (8.9 C) • Protein = 4 • Carbo = 7 • Fat = 9

5. Cellular respiration • The process that releases energy from food in the presence of O2. • Example: • 6O2+C6H12O66CO2+6H20+Energy • Oxygen+glucoseCarbonDioxide+water+Energy

6. Stages of cellular respiration • Glycolysis: poor yield of energy • Anaerobic: without O2 • Aerobic: with O2 • *Krebs Cycle: Better yield • *Electron chain: High yield of energy *happens within Mitochondrion

8. Photo vs. respiration • Opposite processes feed each other

9. Review • Why do all organisms need food? • Why do macromolecules differ in the amount of energy produced? • Cellular respiration? • How are photosynthesis and cellular respiration considered oposite?

10. 9.2 The process of Cellular Respiration • Key Questions: • What happens during the process of glycolysis? • What happens during the krebs cycle? • How does the electron transport chain use high-energy electrons from glycolysis and the krebs cycle • How much energy does cellular respiration generate? • Vocab: • Glycolysis • NAD+ • Krebs Cycle • Matrix

11. Glycolysis: • Definition: First step of cellular respiration “sugar breaking” • Where: in the cytoplasm! • During Glycolysis: 1 molecule of Glucose (6-carbon compound) is transformed into 2 molecules of Pyruvic acid (a 3-carbon compound) • The end result of Glycolysis is: • 2 ATP • 2 NADH • 2 Pyruvic acid • ATP: unit of energy • NAD+: Electron carrier (nicotinamide adenine dinucleotide)

12. Glycolysis continued… Glycolysis: ATP: 2 NADH: 2 • Key points: 2 ATP to start produces 4 ATP Net gain of only 2ATP What happens to the NADH? http://www.youtube.com/watch?v=x-stLxqPt6E

13. Glycolysis continued… • Advantages: • Speed • Can repeat quickly • Does not require O2 • Disadvantages: • Needs ATP to get ATP! • Small yield of ATP

14. Krebs cycle • Definition: second stage of respiration • Where: in the Matrix of the Mitochondria • Matrix: innermost compartment of the mitochondrion and the site of the kreb cycle reactions. • What happens: Pyruvic acid is broken down into carbon dioxide in a series of energy extracting reactions. **because Citric acid is the first compound formed, the kreb is also called the “citric acid cycle.”

15. Krebs cycle…continued Krebs cycle: ATP=2 NADH= 8 FADH=2 CO2=4 The process: • Each Pyruvic acid (2) enters Matrix • Releases NADH! • Converts to Acetyl-CoA • Enters Krebs, becoming citric acid (6-carbon) • O2 removed carbon through Co2 (5-carbon) • NADH! • Another CO2 released (4-carbon) • NADH! • ATP!!!! • FAD • NADH!!! • This happened again with second pyruvic Acid http://www.youtube.com/watch?v=aCypoN3X7KQ 1 2 3 4 5 11 6 7 10 8 9

16. Electron Transport Chain • Last step of cellular respiration • The electron transport chain uses the high-energy electrons from glycolysis and the krebs cycle to convert ADP to ATP • http://www.youtube.com/watch?v=Idy2XAlZIVA

17. Electron Transport chain • NADH and FADH pass their pair of high-energy electrons through the chain • High-energy electrons are passed from one carrier to the next • Transferring of HE electrons through the carriers shifts Hions into the intermembrane space • O2 is final acceptor forming Water • Build up H+ outside membrane • Pressure forces H+ through ATP synthase • Formation of ATP Each pair of electrons yield 3 ATP Electron chain = 32 ATP!!! 5 6 3 2 7 4 1

18. The TOTALS… For each Glucose Molecule: Glycolysis = 2 ATP Krebs = 2 ATP ETC = 32 ATP 36 ATP per each molecule of Glucose!!

19. 9.2 review • What are the products of glycolysis? • What happens to Pyruvic acid in the Krebs? • What are the products of the Krebs? • How does the ETC use the high-energy electrons from glycolysis and krebs? • How does the cell memebrane use the H+ build up to create ATP? • How many molecules of ATP are produced in the entire breakdown of glucose?

20. Lesson Overview 9.3 Fermentation

21. THINK ABOUT IT • We use oxygen to release chemical energy from the food we eat, but what if oxygen is not around? • Is there a pathway that allows cells to extract energy from food in the absence of oxygen? • http://www.5min.com/Video/How-Fermentation-Works-83226972

22. Fermentation • How do organisms generate energy when oxygen is not available?

23. Fermentation • How do organisms generate energy when oxygen is not available? • In the absence of oxygen, fermentation releases energy from food • molecules by producing ATP.

24. Fermentation • Fermentation is a process by which energy can be released from food molecules in the absence of oxygen. Fermentation occurs in the cytoplasm of cells.

25. Fermentation • Under anaerobic conditions, fermentation follows glycolysis. During fermentation, cells convert NADH produced by glycolysis back into the electron carrier NAD+, which allows glycolysis to continue producing ATP.

26. Alcoholic Fermentation • Yeast and a few other microorganisms use alcoholic fermentation that produces ethyl alcohol and carbon dioxide. • This process is used to produce alcoholic beverages and causes bread dough to rise.

27. Alcoholic Fermentation • Chemical equation: • Pyruvic acid + NADH  Alcohol + CO2 + NAD+

28. Lactic Acid Fermentation • Most organisms, including humans, carry out fermentation using a chemical reaction that converts pyruvic acid to lactic acid. • Chemical equation: • Pyruvic acid + NADH  Lactic acid + NAD+

29. Energy and Exercise • How does the body produce ATP during different stages of exercise?

30. Energy and Exercise • How does the body produce ATP during different stages of exercise? • For short, quick bursts of energy, the body uses 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.

31. Quick Energy • Cells normally contain small amounts of ATP produced during cellular respiration, enough for a few seconds of intense activity. • Lactic acid fermentation can supply enough ATP to last about 90 seconds. However, extra oxygen is required to get rid of the lactic acid produced. Following intense exercise, a person will huff and puff for several minutes in order to pay back the built-up “oxygen debt” and clear the lactic acid from the body.

32. Long-Term Energy • For intense exercise lasting longer than 90 seconds, cellular respiration is required to continue production of ATP. • Cellular respiration releases energy more slowly than fermentation does. • The body stores energy in the form of the carbohydrate glycogen. These glycogen stores are enough to last for 15 to 20 minutes of activity. After that, the body begins to break down other stored molecules, including fats, for energy.

33. Long-Term Energy • Hibernating animals like this brown bear rely on stored fat for energy when they sleep through the winter.