Photosynthesis CO5 PDF

PHOTOSYNTHESIS Course Outcome 5 Energy Flows Through the Biosphere Continuously ENERGY METABOLISM General Biology 1 (BIO01) | Course Outcome 5  DEFINITION OF TERMS ENERGY is the ability to promote change or do work. Chemical Energy is stored in the bonds between atoms and...

PHOTOSYNTHESIS Course Outcome 5 Energy Flows Through the Biosphere Continuously ENERGY METABOLISM General Biology 1 (BIO01) | Course Outcome 5  DEFINITION OF TERMS ENERGY is the ability to promote change or do work. Chemical Energy is stored in the bonds between atoms and molecules Solar Energy is harvested from the sun METABOLISM is the sum of all chemical reactions within a cell or an organism. Catabolism is the break down of large molecules into smaller units; exergonic Anabolism is the synthesis of large molecules from smaller units; endergonic  ADENOSINE TRIPHOSPHATE (ATP) primary energy “currency” in ENERGY biological systems METABOLIS energy-intermediate molecule M used to drive cellular processes  STRUCTURE OF ADENOSINE TRIPHOSPHATE (ATP) Acid Anhydride Bond High Energ y Bond Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.  Hydrolysis and Synthesis of ATP High Acid Anhydride Bond Energ y Bond Energy is release d  HYDROLYSIS OF ATP When ATP undergoes hydrolysis, water breaks the phosphoanhydride bond that links the (outermost) phosphate to the second. From this, adenosine diphosphate (ADP) and inorganic phosphate (Pi) are formed. This process is highly exergonic.  The reverse reaction, whereby ADP + Pi ATP is synthesized from ADP and Pi with a loss of a water molecule H 2O by condensation, is correspondingly endergonic. Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.  ATP – ADP Cycle Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings. CELLULAR RESPIRATION (aerobic and anaerobic respiration, fermentation) ATP – ADP CYCLE CELLULAR PROCESSES (movement, anabolic processes, active transport) Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings. Biochemical pathways. Graphical summary of the metabolic pathways found in prokaryotic and eukaryotic cells.  ENERGY METABOLISM Phototrophic Chemotrophic Energy Energy Metabolism Metabolism involve energy- involve reactions yielding oxidative- that obtain energy reductive (oxidation- mainly from reduction) sunlight reactions  Oxidation NADH NAD+ Oxidation is the loss of electrons, Loss of Hydrogen atoms, or gain of oxygen NADH = Nicotinamide Adenine Dinucleotide reduced NAD = Nicotinamide Adenine Dinucleotide  Reduction Fe+3 Fe+2 NAD+ NADH Reduction is the Gain of electrons, Gain of Hydrogen atoms, or loss of oxygen atoms NADH = Nicotinamide Adenine Dinucleotide reduced NAD = Nicotinamide Adenine Dinucleotide  Oxidation-Reduction reaction: coupled Oxidizing agent (Oxidized substrate/reactant) Gains electron and becomes reduced R + NADH RH + NAD+ Reducing agent (Reduced substrate/reactant) Loses electron and becomes oxidized  Reactants Products becomes oxidized becomes reduced Methane Oxygen Carbon dioxide Water (reducing (oxidizing agent) agent)  Oxidizing Reducing agent agent Causes the Causes the oxidation of reduction of FUNCTION another another substrate substrate BEFORE THE Oxidized Reduced REACTION Substrate Substrate DURING THE Gains electron Loses electrons REACTION AFTER THE is reduced is oxidized  Oxidation cannot occur without reduction, and vice versa. The reducing agent becomes oxidized, and the oxidizing agent becomes reduced. Raven, P. H., Johnson, G. B., Mason, K. A., Losos, J., & Duncan, T. (2023). Biology (13th ed.). 2 Penn Plaza,  Photosynthe sis Oxidizing agent (Oxidized substrate/reactant) Gains electron and becomes reduced Not the final product of photosynthesis Reducing agent (Reduced substrate/reactant) Loses electron and becomes oxidized Photosynthesi s Photosynth esis PHOTOTROPHIC ENERGY METABOLISM: Oxygenic Photosynthesis General Biology 1 (BIO01) | Course Outcome 5  Definition of Photosynthesis Types of Organisms that undergo Photosynthesis Structure and Function of COVERAG Chloroplast E Two Stages of Photosynthesis  Light-dependent Reactions  Calvin-Benson Cycle (Light- independent reaction) Overview of PHOTOSYNTHESIS conversion of light energy to chemical energy and its subsequent use in synthesizing organic molecules ORGANISMS INVOLVED: Photoheterotrophs Photoautotrophs  PHOTOSYNTHESIS PHOTOHETEROTROPH PHOTOAUTOTROPHS S uses light as energy uses light as energy source and organic source and inorganic compounds as carbon compounds as carbon source source  Leaves are the major sites of photosynthesis in plants. Chloroplasts are found mainly in the mesophyll cell. Carbon dioxide enters the leaf and, oxygen exits, by way of microscopic pores called stomata. Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.  CHLOROPLAST site of photosynthesis in plants PARTS: Inner membrane Outer membrane Stroma (dense fluid) Thylakoids Grana (stacks of thylakoids) Chlorophyll Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.  TWO STAGES OF PHOTOSYNTHESIS (Light-dependent Reactions) Calvin Cycle (Light-independent Reactions) Disclaimer: DO NOT USE THE TERM “DARK REACTION” Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.  PHOTOSYNTHESIS conversion of light energy to chemical energy and its subsequent use in synthesizing organic molecules TWO STAGES: Light-dependent Reactions Calvin-Benson Cycle (Light- independent) Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.  TWO STAGES OF PHOTOSYNTHESIS (Light-dependent Reactions) occur in thylakoids conversion of light energy to chemical energy (ATP and NADPH) source of hydrogen ions (H+) Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.  TWO STAGES OF PHOTOSYNTHESIS Calvin Cycle (Light-independent Reactions) carbon fixation Reduction of fixed carbon to carbohydrates requires ATP and NADPH from Light- dependent Reactions Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings. How do these two stages of photosynthesis specifically occur? LIGHT-Dependent REACTIONS  Light-dependent Reactions occur in thylakoids conversion of light energy to chemical energy (ATP and NADPH) source of hydrogen ions (H+) Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings. CHLOROPHYLL Light Reflected Light green pigment (light- Chloroplast absorbing molecules) found in thylakoid membranes of chloroplast gives leaves their green color Absorbed light Granum Transmitted light Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings. CHLOROPHYLL Light Reflected Light green pigment (light- Chloroplast absorbing molecules) found in thylakoid membranes of chloroplast gives leaves their green color Absorbed light Granum Transmitted light Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings. Raven, P. H., Johnson, G. B., Mason, K. A., Losos, J., & Duncan, T. (2023). Biology (13th ed.). 2 Penn Plaza, New York: McGraw-Hill. Why do plants appear green? Light Reflected Light Chlorophylls appear green Chloroplast because they reflect and transmit the wavelengths of yellow and green light. Chlorophylls absorb red and violet-blue Absorbed light Granum wavelengths which provide the energy used in Transmitted photosynthesis. light Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings. CHLOROPHYLL Chlorophyll a main photosynthetic pigment Chlorophyll b accessory pigment Raven, P. H., Johnson, G. B., Mason, K. A., Losos, J., & Duncan, T. (2023). Biology (13th ed.). 2 Penn Plaza, New York: McGraw-Hill.  Photosystem STROMA Photon Light- Reaction- Primary harvesting center Chlorophyll molecules, complexes complex electron accessory pigments, and acceptor associated proteins are organized into functional units called photosystems, which are Thylakoid membrane localized into the e thylakoid membranes. Photosystem II - P680 Photosystem I Transfer Special pair of Pigment - P700 of energy chlorophyll a molecules molecules THYLAKOID SPACE (INTERIOR OF THYLAKOID) (a) How a photosystem harvests light Raven, P. H., Johnson, G. B., Mason, K. A., Losos, J., & Duncan, T. (2023). Biology (13th ed.). 2 Penn Plaza, New York: McGraw-Hill.  PHOTOEXCITATIO N When a pigment like chlorophyll absorbs photons from light, energy from photons are transferred to electrons – ground state to excited state When excited electrons go back to the ground state, photons are given off (fluorescence) Light - Dependent Reaction (Linear Electron Flow) ferredoxin NADPH-Nicotinamide adenine dinucleotide phosphate reduced (Reduced form of NADP) CALVIN-BENSON CYCLE Light-independent Reactions  Calvin Cycle occurs in the stroma requires ATP and NADPH from Light – dependent reactions Phases: 1. Carbon Fixation 2. Reduction 3. Regeneration of Ribulose bisphosphate (RuBP)  Input 3 (Entering one at a time) CO2 Phase 1: Carbon fixation Rubisco 3 P P Short-lived intermediate 3P P 6 P Ribulose bisphosphate 3-Phosphoglycerate (RuBP) 6 ATP 6 ADP Calvin Cycle 6 P P 1,3-Bisphosphoglycerate 6 NADPH 6 NADP 6 Pi 6 P Glyceraldehyde 3-phosphate Phase 2: (G3P) Reduction 1 P G3P Glucose and (a sugar) other organic Output compounds Biosynthesis of starch and sucrose Biosynthesis of starch and sucrose Biosynthesis of starch and sucrose Photosynthesis in C3, C4, and CAM Plants General Biology 1 (BIO01) | Course Outcome 5  DEHYDRATION IN PLANTS On hot, dry days, plants close their stomata to conserve water but this limits photosynthesis. Closing the stomata reduces the plant’s access to carbon dioxide and causes oxygen gas to build up. These conditions favor an apparently wasteful process known as photorespiration.  PHOTORESPIRATION In most plants (C3 plants), initial fixation of CO2, via rubisco, forms a three-carbon compound (3- phosphoglycerate) In photorespiration, rubisco adds O2 instead of CO2 in the Calvin cycle, producing a two-carbon compound. Photorespiration consumes O2 and organic fuel and releases CO2 without producing ATP or sugar.  C4 PATHWAY C4 plants minimize the cost of photorespiration by incorporating CO2 into four-carbon compounds in mesophyll cells This step requires the enzyme PEP carboxylase.  CAM PLANTS Some plants, including succulents, use crassulacean acid metabolism (CAM) to fix carbon. CAM plants open their stomata at night, incorporating CO2 into organic acids. Stomata close during the day, and CO2 is released from organic acids and used in the Calvin cycle. References Hardin, J., & Bertoni, G. (2018). Becker's World of the Cell (9th ed.). Pearson. Raven, P. H., Johnson, G. B., Mason, K. A., Losos, J., & Duncan, T. (2023). Biology (13th ed.). 2 Penn Plaza, New York: McGraw-Hill. Urry , L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Orr , R. B. (2021). Campbell Biology (12th ed.). San Francisco, CA: Pearson Benjamin Cummings.