Chapter 4: Cellular Metabolism (Sections 1,3,5,6) KEY CONCEPT All cells need chemical energy.

Transcription

1 KEY CONCEPT All cells need chemical energy.

2 ! The chemical energy used for most cell processes is carried by ATP. Molecules in food store chemical energy in their bonds. Starch molecule Glucose molecule

3 ATP transfers energy from the breakdown of food molecules to cell functions. Energy is released when a phosphate group is removed. ADP is changed into ATP when a phosphate group is added. phosphate removed

4 adenosine triphosphate tri=3 adenosine diphosphate di=2

5 ! Organisms break down carbon-based molecules to produce ATP.

6 Details Carbohydrates are the molecules most commonly broken down to make ATP. not stored in large amounts up to 36 ATP from one glucose molecule Fats store the most energy. 80 percent of the energy in your body about 146 ATP from a triglyceride Proteins are least likely to be broken down to make ATP. amino acids not usually needed for energy about the same amount of energy as a carbohydrate

7 ! A few types of organisms do not need sunlight and photosynthesis as a source of energy. Some organisms live in places that never get sunlight. In chemosynthesis, chemical energy is used to build carbon-based molecules. similar to photosynthesis uses chemical energy instead of light energy

8 KEY CONCEPT Photosynthesis requires a series of chemical reactions.

9 ! The first stage of photosynthesis captures and transfers energy. The light-dependent reactions include groups of molecules called photosystems.

10 Photosystem II captures and transfers energy. chlorophyll absorbs energy from sunlight energized electrons enter electron transport chain water molecules are split oxygen is released as waste hydrogen ions are transported across thylakoid membrane

11 Photosystem I captures energy and produces energycarrying molecules. chlorophyll absorbs energy from sunlight energized electrons are used to make NADPH NADPH is transferred to light-independent reactions

12 ! The second stage of photosynthesis uses energy from the first stage to make sugars. NADPH and ATP from the photosystems are used in the Calvin Cycle. Light-independent reactions occur in the stroma and use CO 2 molecules.

13 A molecule of glucose is formed as it stores some of the energy captured from sunlight. carbon dioxide molecules enter the Calvin cycle energy is added and carbon molecules are rearranged a high-energy three-carbon molecule leaves the cycle

14 A molecule of glucose is formed as it stores some of the energy captured from sunlight. two three-carbon molecules bond to form a sugar remaining molecules stay in the cycle

15 ! Photosynthetic organisms are producers. Producers make their own source of chemical energy. Plants use photosynthesis and are producers. Photosynthesis captures energy from sunlight to make sugars.

16 Chlorophyll is a molecule that absorbs light energy. In plants, chlorophyll is found in organelles called chloroplasts. chloroplast leaf cell leaf

17 ! Photosynthesis in plants occurs in chloroplasts. Photosynthesis takes place in two parts of chloroplasts. grana (thylakoids) stroma chloroplast grana (thylakoids) stroma

18 The light-dependent reactions capture energy from sunlight. take place in thylakoids water and sunlight are needed chlorophyll absorbs energy two energy storing molecules (ATP and NADPH) are produced. The solar energy is used to split water molecules which results in the release of oxygen as a waste product.

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20 The light-independent reactions make sugars. take place in stroma needs carbon dioxide from atmosphere use energy to build a sugar in a cycle of chemical reactions

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22 The equation for the overall process is: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 1 chloroplast granum (stack of thylakoids) 6H 2 O 2 6O 2 6CO 2 thylakoid energy stroma (fluid outside the thylakoids) 1 six-carbon sugar 3 4 C 6 H 12 O 6

23 Photosynthesis Quiz on Wednesday! HW DUE 10/30/03 Define the Key Terms (19) for Chapter 4 on p.129

24 KEY CONCEPT Cellular respiration is an aerobic process with two main stages.

25 ! Glycolysis is needed for cellular respiration. The products of glycolysis enter cellular respiration when oxygen is available. two ATP molecules are used to split glucose four ATP molecules are produced two molecules of NADH produced two molecules of pyruvate produced

26 ! The Krebs cycle is the first main part of cellular respiration. Pyruvate is broken down before the Krebs cycle. carbon dioxide released NADH produced coenzyme A (CoA) bonds to two-carbon molecule

27 The Krebs cycle produces energy-carrying molecules.

28 The Krebs cycle produces energy-carrying molecules. NADH and FADH 2 are made intermediate molecule with CoA enters Krebs cycle citric acid (six-carbon molecule) is formed citric acid is broken down, carbon dioxide is released, and NADH is made five-carbon molecule is broken down, carbon dioxide is released, NADH and ATP are made four-carbon molecule is rearranged

29 ! The electron transport chain is the second main part of cellular respiration. The electron transport chain uses NADH and FADH 2 to make ATP. high-energy electrons enter electron transport chain energy is used to transport hydrogen ions across the inner membrane hydrogen ions flow through a channel in the membrane

30 ! The electron transport chain is the second main part of cellular respiration. The electron transport chain uses NADH and FADH 2 to make ATP. The breakdown of one glucose molecule produces up to 38 molecules of ATP. ATP synthase produces ATP oxygen picks up electrons and hydrogen ions water is released as a waste product

31 KEY CONCEPT Fermentation allows the production of a small amount of ATP without oxygen.

32 If no oxygen is available, cells can obtain energy through the process of anaerobic respiration. A common anaerobic process is fermentation. Fermentation is not an efficient process and results in the formation of far fewer ATP molecules than aerobic respiration. There are two primary fermentation processes: 1. Lactic Acid Fermentation 2. Alcohol Fermentation

33 Lactic acid fermentation occurs when oxygen is not available. For example, in muscle tissues during rapid and vigorous exercise, muscle cells may be depleted of oxygen. They then switch from respiration to fermentation.

34 The pyruvic acid formed during glycolysis is broken down to lactic acid and energy is released (which is used to form ATP). Glucose Pyruvic acid Lactic acid + energy

35 The process of lactic acid fermentation replaces the process of aerobic respiration so that the cell can have a continual source of energy, even in the absence of oxygen. However this shift is only temporary and cells need oxygen for sustained activity.

36 Lactic acid that builds up in the tissue causes a burning, painful sensation.

37 Alcohol fermentation occurs in yeasts and some bacteria. Pyruvic acid formed during glycolysis is broken down to produce alcohol and carbon dioxide and is released (which is used to form ATP).

38 Glucose Pyruvic acid alcohol + carbon dioxide + energy

39 Fermentation is used in food production. Yogurt - Soy Sauce Cheese - Vinegar Bread - Olives/Pickles Beer/ Meade - Wine/ Ale Sauerkraut - Malt

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41 HW Complete Section 4.6 in the Study Guide workbook (p ) Study for Cellular Respiration Quiz on Friday!!