Bio retake

UNIT 3 AP BIOOOOO

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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