Unit 3 Notes
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This 5 page Class Notes was uploaded by Danielle Francy on Monday February 29, 2016. The Class Notes belongs to Bio 190 at Towson University taught by Joseph Velenovsky in Fall 2015. Since its upload, it has received 37 views. For similar materials see Intro Biology for Health Professions in Biology at Towson University.
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Date Created: 02/29/16
Unit 3 Notes Energy: ● Capacity to change or perform work Kinetic Energy: ● Energy of motion Heat: ● Thermal energy ● Associated with random movements of atoms or molecules Potential Energy: ● Energy that matter possesses because of its location or structure ● Molecules also have potential energy based on the arrangement of electrons in the bonds between atoms Chemical Energy: ● Potential energy available for release in a chemical reaction Thermodynamics: ● Study of energy transformations that occur in a collection of matter First Law of Thermodynamics: ● “Law of energy conservation”: energy in the universe is constant and therefore can be transferred and transformed but not created or destroyed. Why can organisms not recycle their energy? ● Every transfer or transformation some energy becomes unusable ● In most energy transformations, some energy is converted to heat ● Heat is a very disordered as measured by entropy. ● Measure of disorder ● Random arrangements of matter have greater entropy ***Glucose has a lot of chemical energy Exergonic Reaction: ● More energy in reactants than products ● Covalent bonds more energy ● Energy is equal to the difference ***Cellular respiration is exergonic Endergonic Reaction: ● More energy in products than reactants ● Energy is equal to difference between products and reactants ● ***Photosynthesis is endergonic ● Makes glucose using carbon dioxide, water, and sun Metabolism: ● Total of an organism’s chemical reactions Metabolic Pathways: ● Series of chemical reactions that either build a complex molecule or break down complex molecules into simpler compounds. Energy Coupling: ● Use energy released from exergonic reactions to drive essential endergonic reactions ATP: ● Renewable resource that cells regenerate ● Know the ATP cycle Phosphate: ● Negative charge ● Very crowded ● Unstable bonds ● Transfer phosphate is called phosphorylation Chemical Work: ● Molecule formed Mechanical Work: ● Protein filament moved Transport Work: ● Solute transported Reaction Graphwithout enzymes: ● Weaken bonds ● Break Reaction Graphwith enzymes: ● Enzymes lower the amount of “hill” or activation energy ● Enzymes allow reactions to occur quickly enough to sustain life ● Heat helps to also speed up reactions ● Speed up all chemical reactions, not just the ones currently needed ● Don’t speed up reactions with heat, rather, enzymes ***Two key characteristics of enzymes: 1. Biological catalyst 2. Not consumed in the reactions they catalyze. ***Enzymes are proteins, but some RNA can act as enzymes(splicing). How do enzymes lower activation energy? ● Contort reactant bonds into a higherenergy unstable state ● Add sucrase in water and hydrolyzed ● Enzymes are very selective because of their unique 3D shapetertiary ● Substrate The substance on which an enzyme reacts ● Tertiary structure determines what enzyme acts upon ● Substratespecific reactant ● Substrate fits into a region of the enzyme called an active site ● Groove or pocket on the surface ● The active site serves to bind the substrate ● The rest of the enzyme serves to preserve the active site Catalytic Cycle: 1. Enzyme available with empty active site 2. Sucrose enters active site attaching through weak bonds ○ Active site changes shape “hugging” the substrate ○ Induced fit model ○ Contort substrate bonds or place R groups in the active site in position to catalyze ○ In reactions with two or more reactants, active site holds the substrates close enough and in the proper placement for the reaction 3. Contorted weakened bond between monosaccharides react with water; products are fructose and glucose ● Reaction is called hydrolysis 4. Product is unchanged. ● Can the enzyme catalyze again? Yes. ● Enzymes have optimal conditions ● Temperature and pH ● Temperature affects molecular movement/motion ● Optimal temp ● Highest rate of contact between substrate and active site ● During denaturation, shape and function change ● 3540 degrees Celsius= temp human enzymes work optimally ● 70 degrees Celsius= temp enzymes of hot spring prokaryotes work at optimally ● Nonprotein aids ● Cofactors=inorganic ions (ex: metals) ● Coenzymes= organic ions (ex: folic acid, riboflavin, niasin) What if enzymes were unregulated? ● Not a good thing ● Cells control enzymes by gene expression or regulation of enzymes ● Inhibitor is a chemical that interferes with an enzyme’s activity ● Some inhibitors resemble an enzyme’s normal substrate ● Competitive inhibitors ● Overcome by increasing substrate concentration because it is more likely to bind to the substrate ● Noncompetitive inhibitor binds on a site called an allosteric site ● This binding changes the shape of the enzyme so active site substrate binding cannot occur. ● Hydrogen bonding between inhibitor and enzyme are reversible ● Product no longer in excess ● ***Feedback inhibitor Photosynthesis: ● Energy comes from sunlight ● Photosynthesis and cellular respiration provide energy for life ● Know the photosynthesis equation ○ CO2+H2O+sunlightC6H12O6+O2 ● Oxygen is consumed in cellular respiration ● In terms of potential energy, glucose can be described as high chemical potential energy ● Energy released in the form of ATP ● Takes place in all eukaryotic cells Cellular Respiration: ● Occurs in mitochondria ● Respiration=exchange of gases ● ATP for cellular work is the most important function ● Exergonic ● Energy in glucose gets stored in ATP by the weakening of bonds ● 32 ATP per glucose molecule ● ***Movement of electrons is a redox reaction ● Oxidation: loss of electrons ● Reduction: gain of electrons ● Electron transfer requires donor and acceptor so both processes occur together ● Hydrogen atoms change location ● Represent electron transfers because each hydrogen atom is an electron(e) and a proton(hydrogen ion or H+) ● Glucose loses electrons ● Oxygen gains electrons ● Electrons overall are transferred from glucose to oxygen(strong electron pull) ● Loses potential energy when it falls ● NAD+=coenzyme important in oxidizing glucose ● Reduced NADH ● ***NADH= high electron carrier ● ***NAD= Nicotinamide Adenine Dinucleotide ● ***FADH= Flavin Adenine Dinucleotide ● Delivers the electrons to the ETC ● ETC=electron transport chains ● All happens in the inner membrane of a mitochondrion ● Oxygen is the final electron acceptor or the electron sink ● Oxygen serves this function because it has a high electronegativity ● Prokaryotic cells that use aerobic respiration occur in cytoplasm and the ETC is built into plasma membrane because there are no organelles.
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