Presentation on theme: "P HOTOSYNTHESIS R EVIEW AND C ELLULAR R ESPIRATION O VERVIEW."— Presentation transcript:
P HOTOSYNTHESIS R EVIEW AND C ELLULAR R ESPIRATION O VERVIEW
E NERGY AND L IFE Plants 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.
P HOTOSYNTHESIS : A N O VERVIEW 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.
P HOTOSYNTHESIS : E QUATION Photosynthesis: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 glucose SUN photons
R EACTIONS OF P HOTOSYNTHESIS 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 membrane Calvin Cycle: uses ATP and NADPH from the light-dependent reactions to produce glucose
C ELLULAR R ESPIRATION Cellular respiration: releases energy by breaking down glucose and other food molecules in the presence of oxygen.
G LYCOLYSIS Glycolysis: breaks one molecule of glucose in half to make 2 pyruvic acid molecules Captures two pairs of high-energy electrons with the carrier NAD+ Does not require energy, supplies chemical energy to cells when oxygen is not available
C HEMICAL E NERGY AND F OOD Food = ENERGY! Energy in food is measured in Calories 1 Calorie = 1000 calories 1 calorie = energy needed to raise the temp. of 1 gram of water by 1⁰ Celsius One molecule of glucose = 3811 calories
O VERVIEW OF C ELLULAR R ESPIRATION EQUATION: C 6 H 12 O 6 + 6O 2 -----> 6CO 2 + 6H 2 0 + energy Glucose + Oxygen Carbon Dioxide + Water + ATP & Heat Controlled release of energy The energy in one glucose molecule may be used to produce 36 ATP Involves a series of 3 reactions --- Glycolysis, Kreb's Cycle, & Electron Transport Chain
G LYCOLYSIS R EACTIONS 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
G LYCOLYSIS R EACTIONS Although glycolysis makes 4 ATP, the net ATP production by this step is 2 ATP (because 2 ATP were used to start glycolysis).
W HAT 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 fermented Anaerobic = no oxygen (called fermentation)
A EROBIC R ESPIRATION Occurs in the mitochondria Includes the Krebs Cycle & the Electron Transport Chain Pyruvic acid from glycolysis diffuses into matrix of mitochondria & reacts with coenzyme A to form acetyl-CoA (2-carbon compound) CO 2 and NADH are also produced
M ITOCHONDRIA Has smooth outer membrane & folded inner membrane Folds are called cristae Space inside cristae is called the matrix & contains DNA & ribosomes Site of aerobic respiration Krebs cycle takes place in matrix Electron Transport Chain takes place in cristae
K REB ’ S C YCLE Named for biochemist Hans Krebs Also known as the Citric acid Cycle Requires 2 cycles to metabolize glucose Pyruvic acid is broken down into CO2 in a series of energy extracting reactions
K REB ’ S C YCLE Steps of Kreb’s Cycle Pyruvic acid (3C) enters mitochondria One 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.
K REB ’ S C YCLE Citric acid is broken down into a 5-C compound, then into a 4-C compound 2 more CO2 get released, and electrons join NAD+ and FAD, forming NADH and FADH2. One molecule of ATP is made TOTAL: 4 NADH, 1 FADH2 and 1 ATP
E LECTRON T RANSPORT C HAIN Follows Krebs Cycle in aerobic respiration Uses the high-energy electrons from the Krebs cycle to convert ADP into ATP
E LECTRON T RANSPORT C HAIN Steps of Electron Transport Chain: High-energy electrons from NADH and FADH2 are passed along the electron transport chain Electrons join with H+ and oxygen at the end to form water As electrons move through chain, H+ are pumped across the membrane creating a gradient H+ move through ATP synthase which combines an ADP and a P to make ATP Each pair of electrons provides enough energy to make 3 ATP
T HE T OTALS How much do we get from one glucose? Glycolysis = 2 ATP Krebs cycle and Electron Transport = 34 ATP For a total of 36 ATP
A NAEROBIC R ESPIRATION Also known as fermentation Releases energy from food molecules by producing ATP in the absence of oxygen NADH converts back to NAD+ by passing electrons back to pyruvic acid (pyruvate)
F ERMENTATION 2 main types Alcoholic fermentation and lactic acid fermentation In the absence of oxygen, yeast and few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes Animals cannot perform alcoholic fermentation, but some cells, such as human muscle cells, can convert glucose into lactic acid
A LCOHOLIC F ERMENTATION Pyruvic acid + NADH alcohol + CO2 + NAD+ Produces CO2 and alcohol Used to make bread, wine, beer, root beer, etc…
L ACTIC A CID F ERMENTATION Pyruvic acid + NADH lactic acid + NAD+ Produced in muscle cells during rapid exercise when the body cannot supply enough oxygen to the tissues Buildup of lactic acid causes a painful, burning sensation Used to make a variety of foods and beverages: cheese, yogurt, buttermilk, pickles, sauerkraut, etc…
O VERALL The products of photosynthesis are similar to the reactants of cellular respiration. The products of cellular respiration are the reactants of photosynthesis.