Presentation on theme: "Photosynthesis Review and Cellular Respiration Overview"— Presentation transcript:
1Photosynthesis Review and Cellular Respiration Overview
2Energy and LifePlants and some other organisms are able to use the light energy from the sun to produce food.The basic energy source for all cells is ATP, but it is not a good energy storage molecule.Glucose can hold 90 times more energy than ATP.
3Photosynthesis: An Overview Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars (glucose) and oxygen.Photosynthesis requires water, carbon dioxide, light and the pigment chlorophyll to make glucose and oxygen.
5Reactions of Photosynthesis 2 Reactions: Light-dependent and Calvin Cycle (light-independent)Light-dependent: produce oxygen, convert ADP and NADP+ into ATP and NADPH, occur in the thylakoid membraneCalvin Cycle: uses ATP and NADPH from the light-dependent reactions to produce glucose
6Cellular RespirationCellular respiration: releases energy by breaking down glucose and other food molecules in the presence of oxygen.
7GlycolysisGlycolysis: breaks one molecule of glucose in half to make 2 pyruvic acid moleculesCaptures two pairs of high-energy electrons with the carrier NAD+Does not require energy, supplies chemical energy to cells when oxygen is not available
8Chemical Energy and Food Food = ENERGY!Energy in food is measured in Calories1 Calorie = 1000 calories1 calorie = energy needed to raise the temp. of 1 gram of water by 1⁰ CelsiusOne molecule of glucose = calories
9Overview of Cellular Respiration EQUATION:C6H12O6 + 6O > 6CO2 + 6H20 + energyGlucose + Oxygen Carbon Dioxide + Water + ATP & HeatControlled release of energyThe energy in one glucose molecule may be used to produce 36 ATPInvolves a series of 3 reactions --- Glycolysis, Kreb's Cycle, & Electron Transport Chain
10Glycolysis Reactions Occurs in the cytoplasm Summary of the steps of Glycolysis:a. 2 ATP added to glucose (6C) to energize it.b. Glucose split to 2 PGAL (3C). (PGAL = phosphoglyceraldehyde)c. H+ and e- taken from each PGAL & given to make 2 NADH.d. NADH is energy and e- carrier.e. Each PGAL rearranged into pyruvate (3C), with energy transferred to make 4 ATP
11Glycolysis ReactionsAlthough glycolysis makes 4 ATP, the net ATP production by this step is 2 ATP (because 2 ATP were used to start glycolysis).
12What happens next?If oxygen is available to the cell, the pyruvate will move into the mitochondria & aerobic respiration will begin.Aerobic = with oxygen (true cell respiration)If no oxygen is available to the cell (anaerobic), the pyruvate will be fermentedAnaerobic = no oxygen (called fermentation)
13Aerobic Respiration Occurs in the mitochondria Includes the Krebs Cycle & the Electron Transport ChainPyruvic acid from glycolysis diffuses into matrix of mitochondria & reacts with coenzyme A to form acetyl-CoA (2-carbon compound)CO2 and NADH are also produced
14Mitochondria Has smooth outer membrane & folded inner membrane Folds are called cristaeSpace inside cristae is called the matrix & contains DNA & ribosomesSite of aerobic respirationKrebs cycle takes place in matrixElectron Transport Chain takes place in cristae
16Kreb’s Cycle Named for biochemist Hans Krebs Also known as the Citric acid CycleRequires 2 cycles to metabolize glucosePyruvic acid is broken down into CO2 in a series of energy extracting reactions
17Kreb’s Cycle Steps of Kreb’s Cycle Pyruvic acid (3C) enters mitochondriaOne carbon is removed, forming CO2 and e- are removed, changing NAD+ into NADH.Coenzyme-A joins the 2C molecule, forming acetyl-CoA.Acetyl-CoA then adds the 2-carbon acetyl group to a 4-carbon compound, forming citric acid.
18Kreb’s Cycle TOTAL: 4 NADH, 1 FADH2 and 1 ATP Citric acid is broken down into a 5-C compound, then into a 4-C compound2 more CO2 get released, and electrons join NAD+ and FAD, forming NADH and FADH2.One molecule of ATP is madeTOTAL: 4 NADH, 1 FADH2 and 1 ATP
19Electron Transport Chain Follows Krebs Cycle in aerobic respirationUses the high-energy electrons from the Krebs cycle to convert ADP into ATP
20Electron Transport Chain Steps of Electron Transport Chain:High-energy electrons from NADH and FADH2 are passed along the electron transport chainElectrons join with H+ and oxygen at the end to form waterAs electrons move through chain, H+ are pumped across the membrane creating a gradientH+ move through ATP synthase which combines an ADP and a P to make ATPEach pair of electrons provides enough energy to make 3 ATP
21The Totals How much do we get from one glucose? Glycolysis = 2 ATP Krebs cycle and Electron Transport = 34 ATPFor a total of 36 ATP
22Anaerobic Respiration Also known as fermentationReleases energy from food molecules by producing ATP in the absence of oxygenNADH converts back to NAD+ by passing electrons back to pyruvic acid (pyruvate)
23Fermentation 2 main types Alcoholic fermentation and lactic acid fermentationIn the absence of oxygen, yeast and few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastesAnimals cannot perform alcoholic fermentation, but some cells, such as human muscle cells, can convert glucose into lactic acid
24Alcoholic Fermentation Pyruvic acid + NADH alcohol + CO2 + NAD+Produces CO2 and alcoholUsed to make bread, wine, beer, root beer, etc…
25Lactic Acid Fermentation Pyruvic acid + NADH lactic acid + NAD+Produced in muscle cells during rapid exercise when the body cannot supply enough oxygen to the tissuesBuildup of lactic acid causes a painful, burning sensationUsed to make a variety of foods and beverages: cheese, yogurt, buttermilk, pickles, sauerkraut, etc…
26OverallThe products of photosynthesis are similar to the reactants of cellular respiration.The products of cellular respiration are the reactants of photosynthesis.