1 Cell Respiration Chap 9 Converting Food Into Cell Energy (ATP)

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1 1 Cell Respiration Chap 9 Converting Food Into Cell Energy (ATP)

2 2 Cell Energy Conversion I.What is energy? A.The ability to do work. II.How do we measure energy in food? A.A calorie is the amount of energy needed to raise the temperature of one gram of water one degree.

3 3 III.Cells store energy in chemical bonds. Blamo!!

4 4 IV.Adenosine Triphosphate (ATP): Basic energy source for all cells.

5 5 V. How does ATP work? Energy is stored by adding Phosphate (P) to ADP & released by removing (P) from ATP.

6 6 VI. Functions of ATP A.Chemical work–supplies energy needed to make all the macromolecules B.Transport work–supplies energy to transport substances across the cell membrane. What do we call this? C.Mechanical work–supplies energy to allow muscle contraction, separation of chromosomes etc. D.ATP is used in almost every function of the cell

7 7 Cellular Respiration I.Definition: The break down of food for energy in the form of ATP. A.When oxygen is present we call this aerobic respiration B.If oxygen is absent we call this anaerobic respiration. C.Enzymes control every step of this process.

8 8 II.All living things use cellular respiration to create cell energy. III.Cellular respiration occurs in the cytoplasm & the mitochondria. IV.Overall chemical equation: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + 38 ATP  GlucoseOxygen Carbon dioxide Waterenergy

9 9

10 10 Respiration is taking in oxygen

11 11 Cellular Respiration occurs in all living things Who uses cell respiration?

12 12 Cellular respiration takes place in and around the mitochondria in the cytoplasm of the cell.

13 13 Cell Respiration Pathways I.Food is broken down and energy is released in a three stage process. A.Glycolysis B.Kreb’s Cycle C.Electron Transport

14 14 Glucose Glycolysis Cytoplasm Pyruvic acid Electrons carried in NADH Krebs Cycle Electrons carried in NADH and FADH 2 Electron Transport Chain Mitochondrion Cellular Respiration: An Overview (fig. 9-2) Mitochondrion Section 9-1

15 15 Glycolysis I.Glycolysis: A.Glucose (6 Carbons) is broken in half to form two pyruvate (3 Carbon) molecules. B.Takes place in the cytoplasm of a cell. C.Doesn’t require oxygen. D.Two ATP molecules are formed.

16 16 Glucose To the electron transport chain Section 9-1 2 Pyruvic acid Glycolysis (fig. 9-3) Greek word Glukus – sweet; Latin word Lysis – to break Net Gain of two ATP!!

17 17 Outer Membrane Inner Membrane Cristae Matrix Mitochondria: The cells power plant!!

18 18 If oxygen is present, the two three- carbon molecules pass into the mitochondria through the pores in the outer membrane.

19 19 II.An intermediate step before Krebs Cycle 1.Pyruvate from the cytoplasm enters the mitochondria. 2.A carbon is removed forming CO 2 as waste. 3.High energy electrons are removed changing NAD + into NADH. 4.Coenzyme A joins the 2-carbon molecule forming acetyle-CoA.

20 The first step of the Krebs Cycle is for Acetyl CoA to combine with a 4-carbon atom to form the 6-carbon atom – Citric acid.

21 For this reason the Krebs Cycle is often referred to as the Citric Acid Cycle

22 22 Krebs Cycle I.Pyruvate is broken down into carbon dioxide. A.Takes place in the matrix of the mitochondria. B.Oxygen must be present.

23 23 Krebs Cycle C.Each time a carbon is removed energy is generated. The energy is captured as NADH and FADH 2

24 24 Krebs Cycle D.The energy from NADH is converted into ATP through an electron Transport System

25 25 Krebs Cycle E.As carbons are removed during the Krebs Cycle they are combined with oxygen to form carbon dioxide.

26 26 Electron Transport Chain I.The Electron transport chain uses high energy electrons from the Krebs cycle to convert ADP into ATP. A.The majority of the ATP produced from breaking down glucose is made by the ETC embedded in the inner membrane space.

27 27 Section 9-2 Electron Transport Hydrogen Ion Movement ATP Production ATP synthase Channel Inner Membrane Matrix Intermembrane Space A.As electrons flow B.Protons are pumped into the intermembrane space. C.As the protons return back through ATP synthase, ATP is produced from ADP. Fig. 9-7

28 28 Electron Transport Chain D.Oxygen is needed to pull electrons through the ETC. E.The ETC phase of respiration produces 18 times more ATP than Glycolysis alone. F.For mitochondria to produce the maximum amount of ATP they must have oxygen and pyruvic acid.

29 The Totals – Cellular Respiration Glycolysis produces just 2 ATP molecules per molecule of glucose. The complete breakdown of glucose, including glycolysis, results in the production of 36 molecules of ATP.

30 Copyright Pearson Prentice Hall The Totals

31 Comparing Photosynthesis and Cellular Respiration The energy flows in photosynthesis and cellular respiration take place in opposite directions.

32 Comparing Photosynthesis and Cellular Respiration On a global level, photosynthesis and cellular respiration are also opposites. –Photosynthesis removes carbon dioxide from the atmosphere and cellular respiration puts it back. –Photosynthesis releases oxygen into the atmosphere and cellular respiration uses that oxygen to release energy from food.

33 33 Aerobic Respiration

34 34 Fermentation I.Fermentation releases energy from glucose under anaerobic (without oxygen) conditions A. 2 types of fermentation are: 1. Alcoholic fermentation 2. Lactic acid fermentation.

35 35 Fermentation II.Alcoholic fermentation. Budding (asexual reproduction) Yeast cells

36 A.Yeast uses alcoholic fermentation to make alcohol (beer, wine) & make bread rise (CO 2 gas). 36

37 37 III.Lactic acid fermentation – Emergency energy system.

38 38 A.Lactic acid is produced in your muscles during rapid exercise when O 2 levels are low. B.Lactic acid fermentation converts glucose into lactic acid.

39 39 C.The buildup of lactic acid in your muscles creates that painful burning sensation.

40 Figure 9-4 Lactic Acid Fermentation The first part of the equation is glycolysis The second part shows the conversion of pyruvic acid to lactic acid.

41 41 Glucose Glycolysis Krebs cycle Electron transport Fermentation (without oxygen) Alcohol or lactic acid Cell energy chemical pathways Section 9-1 Most ATP created


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