6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2. sun. Occurs in chloroplasts ATP. enzymes CO 2 O 2 H 2 O. sugars

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1 Overview Photosynthesis: of Photosynthesis An Overview Photosynthesis process by which plants make food using energy from the sun Plants are autotrophs that make their own source of chemical energy. Chemical equation of photosynthesis: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Occurs in chloroplasts sun CO 2 H 2 O ATP enzymes O 2 sugars

2 Overview Photosynthesis: of Photosynthesis An Overview Chloroplast structure: Double membrane structure Light-dependent reactions take place in the membrane of the thylakoids (stacks of thylakoids = grana) Light-independent reactions take place in stroma (fluid interior of chloroplast) chloroplast grana (thylakoids) stroma leaf leaf cell chloroplast

3 Overview Photosynthesis: of Photosynthesis An Overview Plant pigments in chloroplasts absorb sunlight. Absorb light at different wavelengths (what you don t see) Reflect what is not absorbed (what you see).

4 Overview Photosynthesis: of Photosynthesis An Overview Plant pigments absorb sunlight. Main pigment chlorophyll a absorb at blue and red region and reflect green Accessory pigments chlorophyll b, carotenoid, xanthophyll, carotene absorb closer to green region allowing plant to use light energy across spectrum

5 Overview Photosynthesis: of Photosynthesis An Overview Photosynthesis occurs in two stages. sun ADP NADP ENERGY building reactions (Light Rxn) SUGAR building reactions (Dark Rxn) ATP NADPH used immediately to synthesize sugars H 2 O CO 2 sugar

6 Overview Photosynthesis: of Photosynthesis An Overview Photosynthesis occurs in two stages. Light-dependent reaction - requires sunlight (aka light reaction ) - only runs during daytime - energy-building reaction (making ATP & NADPH) - occurs in thylakoid of chloroplast Light-independent reaction - does not require sunlight (aka dark reaction or Calvin Cycle ) - runs all day - sugar-building reaction (making glucose) - occurs in stroma of chloroplast

7 Photosynthesis The Reactions of in Photosynthesis Detail Light-Dependent Reactions First set of reactions depend on sun for energy Occur in membrane of thylakoids Produces ATP and NADPH energy carrier molecules which will be used to run Light Independent Reactions

8 Photosynthesis The Reactions of in Photosynthesis Detail Light-Dependent Reactions The light-dependent reactions include groups of molecules called photosystems. Photosystem II absorbs sunlight at 680 nm (P680). Photosystem I absorbs sunlight at 700 nm (P700).

9 Photosynthesis The Reactions of in Photosynthesis Detail Photosystem II captures and transfers energy. 1) PS II absorbs sunlight at 680 nm. 2) H 2 O molecules are split; O 2 is released; energized e - enter ETC. 3) H + ions are transported down ETC and pumped across thylakoid membrane PS II

10 Photosynthesis The Reactions of in Photosynthesis Detail Photosystem I captures energy and produces energycarrying molecules. 4) PS I absorbs sunlight at 700 nm 5) energized electrons are used to make NADPH 6) hydrogen ions flow through ATP synthase in the thylakoid membrane 7) ATP synthase makes ATP from ADP 8) NADPH and ATP are sent to stroma to run Light-Independent Reaction PS I

11 Photosynthesis The Reactions of in Photosynthesis Detail Summary of Light-Dependent Reaction

12 Photosynthesis The Reactions of in Photosynthesis Detail Light-Independent Reactions Second set of reactions Do not depend on sunlight Occur in stroma Use CO 2 as source of carbon to build glucose via Calvin Cycle

13 Photosynthesis The Reactions of in Photosynthesis Detail Light-Independent Reactions The Calvin Cycle (aka Carbon Fixation ) 1) Carbon from CO 2 enter the cycle and add to 5-C molecule to form 6-C molecules. 2) ATP and NADPH from Light-Dependent Reactions are used to split the 6-C molecules to 3-C molecules. 3) 3-C molecules are rearranged to form high-energy 3-C molecules. Two 3-C molecules form 2 one 6-C glucose. 3 4) 3-C molecules are changed back to 1 SIX CO 2 make ONE glucose!! 5-C molecules to continue the cycle. 4

14 Chemical Energy and Energy Life and ATP The chemical energy used for most cell processes is carried by ATP. Molecules in food store chemical energy in their bonds. Starch molecule Glucose molecule

15 Chemical Energy and Energy Life and ATP Adenosine Triphosphate (ATP) ATP is the energy molecule most cells use for cellular processes ATP is made up of 3 parts: - a nitrogen base (adenine) - a 5-carbon sugar (ribose) - 3 phosphate groups adenosine triphosphate adenosine diphosphate

16 Chemical Energy and Energy Life and ATP ATP transfers energy from the breakdown of food molecules to cell functions. Energy is released when a phosphate group is removed. (ATP ADP) Energy is stored when a phosphate group is added. (ADP ATP)

17 Overview Chemical of Pathways Cellular Respiration Cellular respiration makes ATP by breaking down sugars. All cells have to use cellular respiration to make energy in the form of ATP. Electrons carried in NADH Electrons carried Pyruvic acid in NADH and FADH 2 Glucose Glycolysis Cytoplasm Mitochondrion

18 Overview Chemical of Pathways Cellular Respiration Chemical Equation of Cellular Respiration This is why we eat. Plants don t eat; they make this with sunlight. The energy released from the glucose is stored in molecules of ATP for later use. Glucose Oxygen Carbon Dioxide Water Energy This is why we breathe oxygen. This is why we breathe out carbon dioxide. The water we can use.

19 Overview Chemical of Pathways Cellular Respiration Two types of Cellular Respiration Aerobic Respiration - requires oxygen - aka Oxidative Respiration Anaerobic Respiration - does not require oxygen - aka Fermentation - Alcohol Fermentation occurs in yeast cells - Lactic Acid Fermentation occurs in muscle cells mitochondrion animal cell

20 Overview Cellular Chemical Respiration of Pathways Cellular in Respiration Details Glycolysis Both types of respiration begin with glycolysis anaerobic process (does not require oxygen) takes place in cytoplasm glucose is broken down 6-C glucose is split into two 3-C pyruvates Electrons carried in NADH Glucose Pyruvic acid Glycolysis Cytoplasm Mitochondrion

21 Overview Cellular Chemical Respiration of Pathways Cellular in Respiration Details Glycolysis 2 pyruvates (or pyruvic acids) are produced 4 ATP are produced, but 2 ATP are used = net production of 2 ATP 2 NADH produced (NADH is a temporary energycarrying molecule which will enter ETC to make ATP) If no oxygen is available fermentation If oxygen is available Krebs Cycle ETC

22 Overview Chemical Fermentation of Pathways Cellular Respiration Anaerobic Respiration (Fermentation) alcohol lactic acid

23 Overview Chemical Fermentation of Pathways Cellular Respiration Anaerobic Respiration (Fermentation) Two types: 1) Alcohol fermentation - pyruvate (3-C) is converted into alcohol (2-C) and CO 2 (1-C) - used by bacteria and yeast in food production (bread, wine, cheese) - makes 2 ATPs from glycolysis

24 Overview Chemical Fermentation of Pathways Cellular Respiration Anaerobic Respiration (Fermentation) 2) Lactic Acid fermentation - pyruvate (3-C) is converted into lactic acid (3-C) - occurs in muscle cells during strenuous exercise for short periods of time due to oxygen debt - makes 2 ATPs from glycolysis

25 Overview Cellular Chemical Respiration of Pathways Cellular in Respiration Details Aerobic Cellular Respiration Cellular respiration that requires O 2 Pyruvate from glycolysis enters the mitochondrion Many ATP are made approx 36 ATP per glucose Much more efficient than anaerobic respiration (only 2 ATP) 3 1 energy from glycolysis and 6O 2 mitochondrion matrix (area enclosed and by inner membrane) 6CO 2 energy 2 ATP inner membrane ATP and 6H 2 O 4 C 6 H 12 O O 2 6 CO H 2 O + 36 ATP

26 Overview Cellular Chemical Respiration of Pathways Cellular in Respiration Details Aerobic respiration occurs in three steps: Glycolysis (in the cytoplasm) Krebs cycle (in the matrix of the mitochondria) Electron Transport system (in the inner membrane of the mitochondria) Electrons carried in NADH Glucose Pyruvic acid Glycolysis Cytoplasm Mitochondrion

27 Overview Cellular The Krebs Respiration of Cycle Cellular and in Respiration Electron Details Transport Chain Krebs Cycle takes place in mitochondrial matrix 2 pyruvates enter the cycle 2 ATP, 8 NADH, 2 FADH 2 and 1 CO 2 (waste product) are produced NADH and FADH 2 are temporary energy-carrying molecules which will enter ETC to make ATP

28 Overview Cellular The Krebs Respiration of Cycle Cellular and in Respiration Electron Details Transport Chain Electron Transport Chain (ETC) takes place in mitochondrial inner membrane All NADH and FADH 2 from glycolysis and Krebs Cycle are converted to ATP 32 ATPs are produced O 2 is necessary for aerobic respiration to act as the final acceptor of the electrons to form H 2 O

29 Overview Cellular The Krebs Respiration of Cycle Cellular and in Respiration Electron Details Transport Chain Summary of ATP Production per Glucose Molecule Glycolysis 2 ATP Krebs Cycle 2 ATP ETC 32 ATP TOTAL: 36 ATP

30 4.4 Overview of Cellular Respiration Comparing Photosynthesis and Cellular Respiration The reactants in photosynthesis are the same as the products of cellular respiration.

31 4.4 Overview of Cellular Respiration Comparing Photosynthesis and Cellular Respiration Photosynthesis Occurs only in presence of light in plant cells Stores energy in glucose CO 2 and H 2 O are raw materials Glucose and O 2 are products Chloroplast is double membrane organelle Has an electron transport system Cellular Respiration Occurs in all cells with or without light Releases energy from glucose to form ATP CO 2 and H 2 O are products Glucose and O 2 are raw materials Mitochondrion is double membrane organelle Has an electron transport system