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Presentation on theme: "P HOTOSYNTHESIS R EVIEW AND C ELLULAR R ESPIRATION O VERVIEW."— Presentation transcript:


2 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.

3 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.

4 P HOTOSYNTHESIS : E QUATION  Photosynthesis:  6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 glucose SUN photons

5 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

6 C ELLULAR R ESPIRATION  Cellular respiration: releases energy by breaking down glucose and other food molecules in the presence of oxygen.

7 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

8 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

9 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

10 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

11 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).

12 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)

13 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

14 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


16 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

17 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.

18 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

19 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

20 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

21 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

22 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)

23 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

24 A LCOHOLIC F ERMENTATION  Pyruvic acid + NADH  alcohol + CO2 + NAD+  Produces CO2 and alcohol  Used to make bread, wine, beer, root beer, etc…

25 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…

26 O VERALL  The products of photosynthesis are similar to the reactants of cellular respiration.  The products of cellular respiration are the reactants of photosynthesis.


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