Photosynthesis, Cellular Respiration and Fermentation

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

phosphate removed  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.

Photosynthesis Overview  Producers make their own source of chemical energy.  Plants use photosynthesis and are producers.  Photosynthesis captures energy from sunlight to make sugars.

 Photosynthesis ◦ Process in which plants use the sun to convert water and carbon dioxide into oxygen and sugars Reactants Products

 Photosynthesis occurs in 2 major stages: ◦ Light Dependent Reactions  Require light  Takes place in thylakoids ◦ Calvin Cycle or Light Independent Reactions  Doesn’t require light  Takes place in stroma

 The light-dependent reactions capture energy from sunlight.  take place in thylakoids  water and sunlight are needed  chlorophyll absorbs energy  energy is transferred along thylakoid membrane then to light-independent reactions  oxygen is released Photosynthesis Overview

 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  also referred to as the Calvin cycle Photosynthesis Overview

 Cellular respiration releases chemical energy from sugars and other carbon based molecules to make ATP when oxygen is present  Cellular respiration is aerobic, or requires oxygen.  Aerobic stages take place in mitochondria. mitochondrion animal cell

 Cellular Respiration ◦ Process that releases energy by breaking down food molecules in the presence of oxygen

 The equation for the overall process is: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O The reactants in photosynthesis are the same as the products of cellular respiration. Cellular Respiration

 Glycolysis must take place first. –anaerobic process (does not require oxygen) –takes place in cytoplasm –splits glucose into two three-carbon molecules –produces 4 ATP molecules but 2 are required to start Cellular Respiration

 When oxygen is present, pyruvate and NADH are used to make large amounts of ATP  This is called aerobic respiration and it takes place in the mitochondria  When oxygen is not present, pyruvate is converted to lactate or ethanol ◦ This is called fermentation

 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 Cellular Respiration

 The Krebs cycle transfers energy to an electron transport chain. ◦ pyruvate is broken down –makes a small amount of ATP –releases carbon dioxide –transfers energy-carrying molecules called NADH and FADH2 6H O 2 6CO 2 6O 2 mitochondrion matrix (area enclosed by inner membrane) inner membrane ATP energy energy from glycolysis and Krebs Cycle Cellular Respiration

Totals:  Glycolysis 2 ATP  Krebs cycle and Electron Transport – 34 ATP TOTAL: 36 ATP Molecules

6H O 2 6CO 2 6O 2 mitochondrion matrix (area enclosed by inner membrane) inner membrane ATP energy energy from glycolysis and The electron transport chain produces a large amount of ATP. oThe electron transport chain uses NADH and FADH2 to make ATP oThe breakdown of one glucose molecule produces up to 38 molecules of ATP oWater is released as a waste product Electron Transport Cellular Respiration

Fermentation

 Fermentation is an anaerobic process.  occurs when oxygen is not available for cellular respiration  does not produce ATP Fermentation allows glycolysis to continue making ATP when oxygen is unavailable. Fermentation

 Fermentation ◦ Anaerobic process ◦ Types:  Alcoholic fermentation  Ethyl alcohol, carbon dioxide are produced  Used by yeasts and microorganisms

 Fermentation ◦ Anaerobic process ◦ Types:  Lactic Acid fermentation  Produces lactic acid  Builds up in muscles during rapid exercise

Comparing Photosynthesis and Cellular Respiration PhotosynthesisRespiration FunctionEnergy StorageEnergy Release LocationChloroplastsMitochondria ReactantsCarbon dioxide and waterGlucose and oxygen ProductsGlucose and oxygenCarbon dioxide and water OrganismsPlants, algae and some bacteria All eukaryotes and some prokaryotes