Unit 3: Cells Processes (Photosynthesis & Respiration)

I.Cell Energy A.ATP  All cells (plant, animal, bacteria, etc.) need energy for active transport, cell division, movement of flagella or cilia, muscle contraction, etc.  Adenosine triphosphate (ATP) stores energy in the chemical bonds between the 3 phosphate groups. The third phosphate bond is weak and when broken, releases energy AMP = one phosphate group AMP = one phosphate group ADP = two phosphate groups ADP = two phosphate groups lesser/no energy available

B. Food you eat is digested to make the ATP you need. * most commonly used Macromolecule broken down Energy released Carbohydrate * 4 calories/mg Lipid 9 cal/mg Protein 4 cal/mg

II. Photosynthesis  process where autotrophs convert sunlight into chemical energy & supports virtually all life on Earth  energy stored as sugars which are used by heterotrophs  occurs in plants and some algae  takes place in the chloroplasts, using chlorophyllchloroplastschlorophyll  6CO 2 + 6H 2 0 C 6 H 12 O 6 + 6O 2  Organisms that do NOT require sunlight to make energy use chemosynthesis (convert chemical energy to make energy storing carbon compounds). These include archaebacteria in extreme environments like deep ocean thermal vents.

A. Light Dependent Reaction 1. occurs in thylakoid membrane of chloroplast 2. begins when energy from sunlight is absorbed by 2. begins when energy from sunlight is absorbed by pigments in photosystem II pigments in photosystem II 3. H 2 O molecules are split into O 2 (released), H + and 3. H 2 O molecules are split into O 2 (released), H + and high energy electrons (e - ) high energy electrons (e - ) 4. H + ions build up in thylakoid and move through ATP 4. H + ions build up in thylakoid and move through ATP synthase into stroma, providing energy to make ATP synthase into stroma, providing energy to make ATP 5. e - go through electron transport chain to photosystem I, where they are accepted by NADP + along with H + to where they are accepted by NADP + along with H + to form NADPH form NADPH

B. Light Independent Reaction 1. also called Calvin cycle or dark reaction 2. occurs in stroma (fluid outside thylakoid) of chloroplast 2. occurs in stroma (fluid outside thylakoid) of chloroplast 3. light not required 3. light not required 4. CO 2 enters undergoes a series of reactions to build high–energy compounds, (G3P then glucose) using energy from ATP and NADPH (from the light 4. CO 2 enters undergoes a series of reactions to build high–energy compounds, (G3P then glucose) using energy from ATP and NADPH (from the light dependent reaction) dependent reaction) 5. These sugars are either stored (as starch or cellulose) or used by the plant for growth & development or used by the plant for growth & development

II.Cellular Respiration A.Overview/Equation  all organisms must breakdown compounds to make ATP energy  cellular respiration involves the breakdown of carbon containing molecules in the presence of O 2 to make ATP in the mitochondria of eukaryotic cells  C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 0 (MEMORIZE!!)  it is a 3 step aerobic process that begins with glycolysis

B.Glycolysis – anaerobic process where glucose is broken down in cytoplasm of cells  Glucose is broken down into 2 simpler 3-carbon molecules called pyruvate  2 molecules of ATP are also produced (only 2% of total chemical energy in glucose) C.Aerobic Respiration 1.Krebs cycle (Citric acid cycle) – if O 2 is present, then pyruvate moves into matrix of mitochondria  Each pyruvate “turns” the Krebs cycle once, releasing 3 CO 2 and one ATP molecule (a net of 6 CO 2 and 2 ATP)  Energy is transferred to next step

2. Electron Transport Chain  Occurs in cristae (inner membrane) of mitochondria  ATP is produced (32 or 34 ATP) which is used for multiple life processes  O 2 is used and reacts with H + and e - to make H 2 O (6 O 2 will produce 6 H 2 O)

D.Anaerobic Respiration (Fermentation)  occurs when not enough/no O 2 is present in cells  does NOT make ATP, but allows glycolysis to continue, which makes small amounts of ATP 1.Lactic acid fermentation – converts pyruvate to lactic acid to lactic acid occurs when muscles run out of O 2 (during intense exercise, etc.) occurs when muscles run out of O 2 (during intense exercise, etc.) “burning” of muscles, soreness “burning” of muscles, soreness lactic acid is diffused back into blood and transported to liver where it is converted back to pyruvate lactic acid is diffused back into blood and transported to liver where it is converted back to pyruvate

2.Alcoholic Fermentation – converts pyruvate to CO 2 and ethanol (ethyl alcohol) used by yeast and some plants; CO 2 makes breads rise, the ethanol evaporates during cooking used by yeast and some plants; CO 2 makes breads rise, the ethanol evaporates during cooking produces wines, beers and other ethanol beverages produces wines, beers and other ethanol beverages  Note: These are the 2 most common types of fermentation. Bacteria use other types to produce yogurts, cheeses and aid in digestion