Results for "Photosystems"

Week 5 - Metabolism - Photosystems

Photosystems and Role of Stomata and Guard Cells

Cell and Structures Cell vs. Viruses • Cells: Simplest living structures capable of performing all life functions independently. • Viruses: Non-living entities requiring a host cell to replicate and survive. Microscopes • Light Microscope: Uses visible light, magnifies up to 1,000x; resolution limited by wavelength of light. • SEM (Scanning Electron Microscope): Creates detailed 3D images of surfaces; does not show internal structures. • TEM (Transmission Electron Microscope): Produces high-resolution images of internal cellular structures. Magnification and Resolution • Magnification: Enlarges an object’s appearance. • Resolution: Measures the clarity of an image by distinguishing two points as separate. Robert Hooke • Coined the term "cells" after observing cork under a microscope. • Published his findings in Micrographia (1665), advancing the study of cells. Cytology and Biochemistry • Cytology: The study of cell structure and function. • Biochemistry: The study of chemical processes and substances within organisms. Cell Fractionation • A laboratory technique to break apart cells and isolate organelles for detailed study. Size Limitations of Cells • Smaller cells have a higher surface area-to-volume ratio, which is essential for efficient exchange of materials. Prokaryotes vs. Eukaryotes • Prokaryotes: No nucleus or membrane-bound organelles; simpler and smaller (e.g., bacteria). • Eukaryotes: Have a nucleus and membrane-bound organelles; larger and more complex. Cell Structures and Functions • Nucleus: Stores genetic material (DNA). • Plasma Membrane: Protects the cell; regulates material exchange. • Cytosol: Fluid portion of the cytoplasm where cellular processes occur. • Microvilli: Increases surface area for absorption in some animal cells. • Cytoskeleton: ◦ Microfilaments (actin): Provides structural support. ◦ Microtubules: Involved in transport and motility. • Animal Cell-Specific Structures: ◦ Desmosomes: Anchor cells together. ◦ Gap Junctions: Channels that allow communication between cells. ◦ Tight Junctions: Create a watertight seal between cells. • Extracellular Matrix (ECM): Nonliving material outside cells, providing structural and biochemical support. • Plant Cell-Specific Structures: ◦ Plasmodesmata: Channels connecting cytoplasm between plant cells. Cellular Respiration Definition • Process of extracting energy from glucose to produce ATP, the cell's main energy currency. ATP • Made by the enzyme ATP synthase, powered by hydrogen ion (H⁺) movement across the inner mitochondrial membrane. Three Stages of Respiration 1 Glycolysis (Cytoplasm): ◦ Reactants: Glucose. ◦ Products: 2 Pyruvate, 2 ATP (net), and NADH. 2 Krebs Cycle (Mitochondrial Matrix): ◦ Reactant: Acetyl CoA. ◦ Products: CO₂, NADH, FADH₂, and 2 ATP. 3 Electron Transport Chain (ETC) (Inner Mitochondrial Membrane): ◦ Reactants: NADH and FADH₂ (electron carriers). ◦ Products: Water and ~32-34 ATP. Key Points • No oxygen = no Krebs cycle or ETC; only 2 ATP are produced via glycolysis. • Fermentation occurs in anaerobic conditions: ◦ Converts pyruvate into lactic acid (in animals) or ethanol (in yeast). Photosynthesis Overview • Process where plants convert light energy into chemical energy (sugars). • Formula: CO2+H2O→O2+G3PCO_2 + H_2O \rightarrow O_2 + G3PCO2​+H2​O→O2​+G3P. Key Concepts 1 Light Reactions (Thylakoid Membranes): ◦ Products: ATP and NADPH (used in the Calvin Cycle). ◦ Oxygen is produced by Photosystem II. 2 Calvin Cycle (Stroma): ◦ Uses ATP and NADPH to fix carbon dioxide into G3P (a sugar precursor). Photosystems • Photosystem II: Produces oxygen and ATP. • Photosystem I: Produces NADPH. Adaptations • C4 Pathway: Spatial separation of steps to avoid photorespiration. • CAM Pathway: Temporal separation, stomata open at night to reduce water loss. Mitosis and Meiosis Mitosis • Division of a eukaryotic somatic (non-reproductive) cell into two identical diploid cells. • Phases: 1 Prophase: Chromosomes condense; spindle forms. 2 Metaphase: Chromosomes align at the cell's equator. 3 Anaphase: Sister chromatids separate. 4 Telophase: Nuclear envelopes reform. 5 Cytokinesis: Cytoplasm splits into two cells. Meiosis • Specialized cell division in germ cells (ovaries/testes) to produce gametes. • Key Features: ◦ Two divisions produce four genetically unique haploid cells. ◦ Crossing over occurs during Prophase I for genetic diversity. Binary Fission • A simple form of cell division in prokaryotes producing two identical cells. Genetics • Haploid: Single set of chromosomes (e.g., gametes). • Diploid: Two sets of chromosomes (e.g., somatic cells). • Punnett Squares and Pedigrees: Tools to predict genetic inheritance. Cell and Structures Cell vs. Viruses • Cells: Simplest living structures capable of performing all life functions independently. • Viruses: Non-living entities requiring a host cell to replicate and survive. Microscopes • Light Microscope: Uses visible light, magnifies up to 1,000x; resolution limited by wavelength of light. • SEM (Scanning Electron Microscope): Creates detailed 3D images of surfaces; does not show internal structures. • TEM (Transmission Electron Microscope): Produces high-resolution images of internal cellular structures. Magnification and Resolution • Magnification: Enlarges an object’s appearance. • Resolution: Measures the clarity of an image by distinguishing two points as separate. Robert Hooke • Coined the term "cells" after observing cork under a microscope. • Published his findings in Micrographia (1665), advancing the study of cells. Cytology and Biochemistry • Cytology: The study of cell structure and function. • Biochemistry: The study of chemical processes and substances within organisms. Cell Fractionation • A laboratory technique to break apart cells and isolate organelles for detailed study. Size Limitations of Cells • Smaller cells have a higher surface area-to-volume ratio, which is essential for efficient exchange of materials. Prokaryotes vs. Eukaryotes • Prokaryotes: No nucleus or membrane-bound organelles; simpler and smaller (e.g., bacteria). • Eukaryotes: Have a nucleus and membrane-bound organelles; larger and more complex. Cell Structures and Functions • Nucleus: Stores genetic material (DNA). • Plasma Membrane: Protects the cell; regulates material exchange. • Cytosol: Fluid portion of the cytoplasm where cellular processes occur. • Microvilli: Increases surface area for absorption in some animal cells. • Cytoskeleton: ◦ Microfilaments (actin): Provides structural support. ◦ Microtubules: Involved in transport and motility. • Animal Cell-Specific Structures: ◦ Desmosomes: Anchor cells together. ◦ Gap Junctions: Channels that allow communication between cells. ◦ Tight Junctions: Create a watertight seal between cells. • Extracellular Matrix (ECM): Nonliving material outside cells, providing structural and biochemical support. • Plant Cell-Specific Structures: ◦ Plasmodesmata: Channels connecting cytoplasm between plant cells. Cellular Respiration Definition • Process of extracting energy from glucose to produce ATP, the cell's main energy currency. ATP • Made by the enzyme ATP synthase, powered by hydrogen ion (H⁺) movement across the inner mitochondrial membrane. Three Stages of Respiration 1 Glycolysis (Cytoplasm): ◦ Reactants: Glucose. ◦ Products: 2 Pyruvate, 2 ATP (net), and NADH. 2 Krebs Cycle (Mitochondrial Matrix): ◦ Reactant: Acetyl CoA. ◦ Products: CO₂, NADH, FADH₂, and 2 ATP. 3 Electron Transport Chain (ETC) (Inner Mitochondrial Membrane): ◦ Reactants: NADH and FADH₂ (electron carriers). ◦ Products: Water and ~32-34 ATP. Key Points • No oxygen = no Krebs cycle or ETC; only 2 ATP are produced via glycolysis. • Fermentation occurs in anaerobic conditions: ◦ Converts pyruvate into lactic acid (in animals) or ethanol (in yeast). Photosynthesis Overview • Process where plants convert light energy into chemical energy (sugars). • Formula: CO2+H2O→O2+G3PCO_2 + H_2O \rightarrow O_2 + G3PCO2​+H2​O→O2​+G3P. Key Concepts 1 Light Reactions (Thylakoid Membranes): ◦ Products: ATP and NADPH (used in the Calvin Cycle). ◦ Oxygen is produced by Photosystem II. 2 Calvin Cycle (Stroma): ◦ Uses ATP and NADPH to fix carbon dioxide into G3P (a sugar precursor). Photosystems • Photosystem II: Produces oxygen and ATP. • Photosystem I: Produces NADPH. Adaptations • C4 Pathway: Spatial separation of steps to avoid photorespiration. • CAM Pathway: Temporal separation, stomata open at night to reduce water loss. Mitosis and Meiosis Mitosis • Division of a eukaryotic somatic (non-reproductive) cell into two identical diploid cells. • Phases: 1 Prophase: Chromosomes condense; spindle forms. 2 Metaphase: Chromosomes align at the cell's equator. 3 Anaphase: Sister chromatids separate. 4 Telophase: Nuclear envelopes reform. 5 Cytokinesis: Cytoplasm splits into two cells. Meiosis • Specialized cell division in germ cells (ovaries/testes) to produce gametes. • Key Features: ◦ Two divisions produce four genetically unique haploid cells. ◦ Crossing over occurs during Prophase I for genetic diversity. Binary Fission • A simple form of cell division in prokaryotes producing two identical cells. Genetics • Haploid: Single set of chromosomes (e.g., gametes). • Diploid: Two sets of chromosomes (e.g., somatic cells). • Punnett Squares and Pedigrees: Tools to predict genetic inheritance.

Here are the answers to your biology questions: 1. Definitions: * Metabolism: The sum total of all chemical reactions that occur within a living organism. * Catabolism: The breakdown of complex molecules into simpler ones, releasing energy. * Anabolism: The synthesis of complex molecules from simpler ones, requiring energy input. * Endergonic Reaction: A reaction that requires an input of energy to proceed. * Exergonic Reaction: A reaction that releases energy. 2. Role of Enzymes in Metabolism: Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy. They bind to specific substrates, forming an enzyme-substrate complex, and catalyze the reaction. This allows metabolic processes to occur at rates compatible with life. 3. Enzyme Activity: * Activation Energy: The minimum amount of energy required for a reaction to occur. * Catalyst: A substance that speeds up a chemical reaction without being consumed in the process. * Active Site: The specific region on an enzyme where the substrate binds. * Denaturation: The loss of an enzyme's shape and function, often due to extreme temperature or pH. * Substrate: The molecule upon which an enzyme acts. * Enzyme-Substrate Complex: A temporary complex formed when an enzyme binds to its substrate. * Suffix -ase: Commonly used to denote enzymes, such as sucrase, protease, and lipase. 4. Oxidation-Reduction Reactions in Cellular Respiration: In cellular respiration, oxidation-reduction reactions involve the transfer of electrons and hydrogen ions. Oxidation is the loss of electrons (and often hydrogen atoms), while reduction is the gain of electrons (and often hydrogen atoms). Energy is released during these reactions and is used to produce ATP. 5. Balanced Equation for Cellular Respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP) 6. Structure of a Mitochondrion: * Outer Membrane: Encloses the mitochondrion. * Inner Membrane: Folded into cristae, increasing surface area for ATP production. * Intermembrane Space: The space between the outer and inner membranes. * Matrix: The fluid-filled space inside the inner membrane, containing enzymes for the citric acid cycle. 7. Glycolysis: Glycolysis is the breakdown of glucose into pyruvate. It occurs in the cytoplasm and produces 2 ATP, 2 NADH, and 2 pyruvate molecules. 8. Citric Acid Cycle: The citric acid cycle, also known as the Krebs cycle, occurs in the mitochondrial matrix. It completely oxidizes pyruvate, producing 2 ATP, 6 NADH, and 2 FADH₂ molecules per glucose molecule. 9. Electron Transport Chain and Oxidative Phosphorylation: The electron transport chain is a series of protein complexes embedded in the inner mitochondrial membrane. Electrons from NADH and FADH₂ are transferred through the chain, releasing energy that is used to pump protons into the intermembrane space. The resulting proton gradient drives ATP synthesis through ATP synthase. 10. ATP and NADH Production: * Glycolysis: 2 ATP, 2 NADH * Citric Acid Cycle: 2 ATP, 6 NADH, 2 FADH₂ * Electron Transport Chain: ~32 ATP (from NADH and FADH₂) 11. Structure and Function of a Dicot Leaf: Dicot leaves are typically broad and flat, with a network of veins. They have a waxy cuticle to prevent water loss, stomata for gas exchange, and mesophyll cells containing chloroplasts for photosynthesis. 12. Structure of a Chloroplast: * Thylakoid: A flattened, disc-shaped sac. * Thylakoid Membrane: The membrane surrounding the thylakoid. * Thylakoid Space: The interior of the thylakoid. * Stroma: The fluid-filled space outside the thylakoids. * Grana: Stacks of thylakoids. 13. Site of Light-Dependent and Light-Independent Reactions: * Light-Dependent Reactions: Thylakoid membrane * Light-Independent Reactions (Calvin Cycle): Stroma 14. Balanced Equation for Photosynthesis: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂ * Carbon (C) from CO₂ is incorporated into glucose. * Hydrogen (H) from water (H₂O) is incorporated into glucose. * Oxygen (O) from water is released as O₂. 15. Dual Nature of Light: Light exhibits both wave-like and particle-like properties. As a wave, it has a wavelength and frequency. As a particle, it consists of photons, discrete packets of energy. 16. Light Reactions: Light energy is absorbed by pigments in photosystems I and II, exciting electrons. These electrons are transferred through a series of electron carriers, generating ATP and NADPH. Water is split, releasing oxygen as a byproduct. 17. Calvin Cycle: The Calvin cycle uses ATP and NADPH from the light reactions to fix CO₂ from the atmosphere. CO₂ is incorporated into RuBP, forming 3-PGA. 3-PGA is reduced to G3P, which can be used to synthesize glucose or regenerate RuBP. 18. Role of Photosynthetic Pigments: Photosynthetic pigments, such as chlorophyll a, chlorophyll b, and carotenoids, absorb light energy and transfer it to the reaction center of photosystems. 19. Role of Photosystems: Photosystems I and II are protein complexes containing pigments and electron carriers. They absorb light energy and use it to excite electrons, initiating the electron transport chain. 20. Phases of the Calvin Cycle: * Carbon Fixation: CO₂ is fixed to RuBP, forming 3-PGA. * Reduction: 3-PGA is reduced to G3P using ATP and NADPH. * Regeneration of RuBP: G3P is used to regenerate RuBP, allowing the cycle to continue. 21. ATP, NADPH, and CO₂ Requirements: * To produce 1 G3P molecule: 9 ATP, 6 NADPH, and 3 CO₂ * To produce 1 glucose molecule: 18 ATP, 12 NADPH, and 6 CO₂ I

ENE-1.D = Describe the properties of enzymes. The structure of enzymes includes the active site that specifically interacts with substrate molecules For an enzyme-mediated chemical reaction to occur = the shape & charge of the substrate must be compatible with the active site of the enzyme ENE-1.E = Explain how enzymes affect the rate of biological reactions The structure and function of enzymes contribute to the regulation of biological processes Enzymes are biological catalysts that facilitate chemical reactions (speed up) in cells by lowering the activation energy ENE-1.F = Explain how changes to the structure of an enzyme may affect its function Change to the molecular structure of a component in an enzymatic system may result in a change of the function or efficiency of the system Denaturation of an enzyme occurs when the protein structure is disrupted → eliminating the ability to catalyze reactions Environmental temperatures & pH outside the optimal range for a given enzyme will cause changes to its structure → altering the efficiency with which it catalyzes reactions In some cases, enzyme denaturation is reversible → allowing the enzyme to regain activity ENE-1.G = Explain how the cellular environment affects enzyme activity Environmental pH can alter the efficiency of enzyme activity = including through disruption of hydrogen bonds that provide enzyme structure The relative concentrations of substrates & products determine how efficiently an enzymatic reaction proceeds Higher environmental temperatures increase the speed of movement of molecules in a solution → increasing the frequency of collisions between enzymes & substrates → therefore increasing the rate of reaction Competitive inhibitor molecules can bind reversibly or irreversibly to the active site of the enzyme Noncompetitive inhibitors can bind allosteric sites = changing the activity of the enzyme ENE-1.H = Describe the role of energy in living organisms All living systems require constant input of energy Life requires a highly ordered system & does not violate the second law of thermodynamics Energy input must exceed energy loss to maintain order & to power cellular processes Cellular processes that release energy may be coupled with cellular processes that require energy Loss of order or energy flow results in death Energy-related pathways in biological systems are sequential to allow for a more controlled & efficient transfer of energy A product of a reaction in a metabolic pathway is generally the reactant for the subsequent step in the pathway ENE-1.I = Describe the photosynthetic processes that allow organisms to capture & store energy Organisms capture & store energy for use in biological processes Photosynthesis captures energy from the sun & produces sugars Photosynthesis first evolved in prokaryotic organisms Scientific evidence supports the claim that prokaryotic (cyanobacterial) photosynthesis was responsible for the production of an oxygenated atmosphere Prokaryotic photosynthetic pathways were the foundation of eukaryotic photosynthesis The light-dependent reactions of photosynthesis in eukaryotes = involve a series of coordinated reaction pathways that capture energy present in light to yield ATP & NADPH (power the production of organic molecules) ENE-1.J = Explain how cells capture energy from light & transfer it to biological molecules for storage & use During photosynthesis = chlorophylls absorb energy from light = boosting electrons to a higher energy level in photosystems I & II Photosystems I & II are embedded in the internal membranes of chloroplasts & are connected by the transfer of higher energy electrons through an electron transport chain (ETC) When electrons are transferred between molecules in a sequence of reactions as they pass through the ETC = an electrochemical gradient of protons (hydrogen ions) is established across the internal membrane The formation of the proton gradient is linked to the synthesis of ATP from ADP & inorganic phosphate via ATP synthase The energy captured in the light reactions & transferred to ATP + NADPH = powers the production of carbohydrates from carbon dioxide in the Calvin cycle (which occurs in the stroma of the chloroplast) ENE-1.K = Describe the processes that allow organisms to use energy stored in biological macromolecules Fermentation & cellular respiration = use energy from biological macromolecules to produce ATP Respiration & fermentation = characteristic of all forms of life Cellular respiration in eukaryotes = involves a series of coordinated enzyme-catalyzed reactions that capture energy from biological macromolecules The electron transport chain = transfers energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes Electron transport chain reactions = occur in chloroplasts / mitochondria / prokaryotic plasma membranes In cellular respiration = electrons delivered by NADH & FADH2 = passed to a series of electron acceptors (as they move toward the terminal electron acceptor = oxygen) In photosynthesis = the terminal electron acceptor is NADP+ Aerobic prokaryotes = use oxygen as a terminal electron acceptor anaerobic prokaryotes = use other molecules The transfer of electrons = accompanied by the formation of a proton gradient across the inner mitochondrial membrane / the internal membrane of chloroplasts (with the membrane(s) separating a region of high proton concentration from a region of low proton concentration In prokaryotes = the passage of electrons is accompanied by the movement of protons across the plasma membrane. The flow of protons back through membrane-bound ATP synthase by chemiosmosis drives the formation of ATP from ADP & inorganic phosphate known as oxidative phosphorylation in cellular respiration photophosphorylation in photosynthesis In cellular respiration = decoupling oxidative phosphorylation from electron transport generates heat This heat can be used by endothermic organisms to regulate body temperature ENE-1.L = Explain how cells obtain energy from biological macromolecules in order to power cellular functions Glycolysis = a biochemical pathway that releases energy in glucose to form ATP from ADP & inorganic phosphate / NADH from NAD+ /pyruvate Pyruvate = transported from the cytosol to the mitochondrion = where further oxidation occurs In the Krebs cycle = carbon dioxide is released from organic intermediates = ATP is synthesized from ADP + inorganic phosphate & electrons are transferred to the coenzymes NADH + FADH2 Electrons extracted in glycolysis & Krebs cycle reactions = transferred by NADH & FADH2 to the electron transport chain in the inner mitochondrial membranE When electrons are transferred between molecules in a sequence of reactions as they pass through the ETC = an electrochemical gradient of protons (hydrogen ions) across the inner mitochondrial membrane is established Fermentation allows glycolysis to proceed in the absence of oxygen & produces organic molecules (including alcohol & lactic acid = as waste products) The conversion of ATP to ADP = releases energy = which is used to power many metabolic processes SYI-3.A = Explain the connection between variation in the number & types of molecules within cells to the ability of the organism to survive and/or reproduce in different environments. Variation at the molecular level = provides organisms with the ability to respond to a variety of environmental stimuli Variation in the number & types of molecules within cells provides organisms a greater ability to survive and/or reproduce in different environments Kk

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