Energy in the Cell

1. Energy in the Cell

2. I. The Need for Energy Section 9.1 Summary – pages 221-224 A. Allliving organisms must be able to obtain energyfrom the environment in which they live. B. Autotrophs-Plantsand other greenorganisms are able to trapthelightenergy in sunlightandstoreit in the bonds of certain molecules for later use. C.Heterotrophscannot use sunlight directly, they eatplantsorotherheterotrophs that eat plants to obtain energy.

3. D. Cells require energyfor various activities. 1. activetransport 2. cell division 3. movementof flagella or cilia 4.production,transport, and storageof proteins. E. ATP(adenosine triphosphate) is a molecule that providesquicksource of energyfor any organelle in the cell that needs it.

4. Section 9.1 Summary – pages 221-224 1. ATP is composed of an adenosinemolecule with 3phosphategroups attached. 2. As morephosphategroups are added, moreenergyis required to make the molecule. 3. When the phosphate bonds are broken, energy isreleasedand is available to the cell. 4. When ATP is broken down the energy must be capturedand used efficientlyby cells. 5. Many proteinshave a specific sitewhere ATP can bind.

5. Adenosine 3 phosphate groups 2 phosphate groups

6. II. Trapping Energy from Sunlight A. The process that uses the sun’s energy to make simple sugars is called photosynthesis. B. The general equation for photosynthesis is written as 6CO2 +6H2O + sunlight →C6H12O6 + 6O2 C. Chlorophyll, a greenpigment found in chloroplastsand infolded membranes of photosynthetic bacteria, absorbs almost all wavelengths of light except green. D. Photosynthesis happens in 2phases.

7. Thelight-dependentreactions convert light energy into chemical energy. • a. sunlight excitesthe electrons in the chlorophyll. • b. The excited electrons canconvertADP to ATP. • c. Watermolecules are broken into H+ions and O2gas 2. ATP produced in the light-dependent reactions is used to fuel the light-independentreactions that produce simple sugars. a. In the CalvinCycle,CO2is converted into 3-carbonchains. b. 3-carbon chains are converted into sugarand other carbohydrates.

9. III. Converting Food into Energy A.Cellularrespirationis the process by which cells break down food molecules to produce ATP.C6H12O6+ 6O2 6CO2+ 6 H2O + energy B. There are 3stages of cellular respiration. 1.Glycolysis– breaking down glucose a. is anaerobic- no oxygen is required. b. breaks glucoseinto 2 3-carbon molecules c. produces only 2ATP molecules d. takes place in the cytoplasm

10. 2. CitricAcidCycleor Krebs cycle, is a series of chemical reactions that breaks down 3-carbon molecules into CO2. a. at each turn of the cycle, 1 ATP and 2 CO2 are produced b. occurs inside the inner membrane of mitochondria Section 9.3 Summary – pages 231-237 3. ElectronTransportChain a. molecules of NADH and FADH2give up electronsthat pass through a series of reactions. b. occurs inside mitochondria c. requires oxygenand produces 32ATP molecules

11. Citric acid cycle

12. C. Fermentation– an anaerobicprocess that supplies energy when oxygen is not available. 1. Lacticacidfermentation – produces lactic acid in animals (build up of lactic acid causes the “burn” we feel in our muscles) 2. Alcoholicfermentation - used by yeast cells and some bacteria to produce CO2 and ethyl alcohol. (important to baking and production of wine and other alcoholic beverages) Section 9.3 Summary – pages 231-237

13. Comparison of Photosynthesis and Cellular Respiration

14. The End