BIOL 240 1st EditionExam # 2 Study Guide Lectures: 7-10Lecture 7 (February 3) Membranes- Phospholipids Most abundant lipid in most membranes Amphipathic molecule: has two opposite sides (hydrophilic and hydrophobic) Lateral movement in membraneo Types of Phospholipid Tails Viscous: saturated tails pack together Fluid: unsaturated tails prevent packing- Cholesterolo At warm temperatures, cholesterol restrains movement of phospholipidso At cool temperatures, cholesterol prevents packing- Integral & peripheral membrane proteinso Integral: goes all the way across the membraneo Peripheral: does not go all the way through; remains on ends- 6 jobs of membrane proteinso Transport, enzymatic activity, cell-cell recognition, intercellular joining, signal transduction, attachment to the cytoskeleton and intercellular matrix- Sidedness of membraneso Membranes have distinct inside and outside faceso Asymmetrical distribution of proteins, lipids, and carbohydrateso Determined when the membrane is built by ER- Types of molecules that can cross membrane o Nonpolar, small molecules cross easily Hydrocarbonso Polar, large molecules do not cross easily Sugars Large: break the membrane Polar: thermodynamically unfavorable- Membrane transport--passive vs active and different typeso Passive: does not require energy Moving across the membrane with the concentration gradiento Active: requires energy Moves across the membrane against the concentration gradient- Tonicityo Animal Cell Lysed cell: Hypotonic: salt concentration inside of cell is greater than outside (water goes into cell) Normal cell: Isotonic: salt concentration inside of cell equals the outside Shriveled cell: Hypertonic: salt concentration inside of cell is less than outside (water goes out of cell)o Plant Cell Turgid (normal) cell: Hypotonic: water goes into cell Flaccid cell: Isotonic: water goes into and out of cell at the same rate Plasmolyzed cell: water goes out of cell- Endocytosis & exocytosiso Exocytosis: bringing stuff outside of cello Endocytosis: bringing stuff inside of cell- Cell signaling with kinases & phosphataseso Cell-to-cell communicationo Allows multicellular organisms to coordinate activitieso Also essential for many multicellular organisms Quorum signaling: group collaborationo Kinases: adds phosphate groups to moleculeso Phosphatases: takes phosphate groups from moleculesLecture 8 (February 5) Metabolism- Catabolism and Anabolism o Catabolic pathway Polymers to monomers Cellular respirationo Anabolic pathways Monomers to polymers Protein synthesis- Forms of energyo Kinetic: motiono Chemical: reaction- First & second law of thermodynamics  The first law of thermodynamics- Energy of the universe is constant- Energy can be transferred and transformed but it cannot be created or destroyed The second law of thermodynamics- During every energy transfer, some energy is lost as heat- Entropy- Free energy & deltaG-endergonic & exergonic reactions o Free energyo Spontaneous reactions don’t require energy inputo Negative delta G = spontaneouso Can be applied to the Chemistry of Life’s processeso Exergonic reaction: energy is not neededo Endergonic reaction: energy is required- Cellular worko A cell does three main kinds of work Mechanical: movement Transport: moving across membrane Chemicalo Uses energy couplingo Mediated by ATP- ATPo Composed of ribose, adenine, and the phosphate groups- Regeneration of ATPo Catabolic pathways yield energy through Chemical reactions- Transfer of electrons stored in organic molecules- Releases energy- Energy used to synthesize ATP- Activation energy & enzymeso Activation Energy A “push” of energy to start the reaction Enzyme: decreases activation energy; increase rate of reaction- Enzyme active site and specificity o Enzymes Substrate: binds to enzyme Active site: where enzymes and substrates bind Enzyme specificity Changed by environmental conditions- Competitive & noncompetitive inhibition o Competitive inhibition: substrate is replaced by a competitive inhibitor binding to the active siteo Noncompetitive (allosteric) inhibition: noncompetitive inhibitor binds to the allosteric site which changes the shape of the active site so the substrate cannot bind- Feedback inhibitiono Wants to stop reactiono Final product binds allosteric-ally to the initial reaction- Lecture 9 (February 10) Redox reactions, flow of electrons, hydrogens, energyo Chemical reactions that transfer electrons between reactionso Oxidation: loses electrons, H (losing energy)o Reduction: gains electrons, H (gaining energy)Cellular respiration- Reactants, productso C6H12O6 + 6O2  6CO2 + 6H2O- As a redox reactiono During cellular respiration, glucose (fuel) is oxidized and O2 is reduced.- 3 stages & where they take placeo Glycolysis: Glucose  2 pyruvate Occurs in cytoplasm  Occurs whether or not oxygen is present Makes 2ATP and 2NADH Two major phases:- Energy investment phase- Energy payoff phaseo Pyruvate Oxidation and Citric Acid Cycle Pyruvate Oxidation- Pyruvate  Acetyl CoA Citric Acid Cycle- Acetyl CoA  Citric Acid Cycle- 4 CO2- 6 NADH- 2 ATP- 2 FADH2 Energy- Energy from glucose goes to the electron carrierso Oxidation Phosphorylation Electron transport chain- NADH and FADH2 pass the electrons to the electron transport chain- Release energy in stepwise amounts (going down in energy)- Final electron acceptor: Oxygen (why we breathe)- Energy pumps hydrogen across membrane (active transport: against gradient) Chemiosmosis- Energy is stored as a H+ gradient- Coupled to ATP synthesis- Proton-motive force- What’s the point of cellular respiration (i.e. how many ATP are made)o Makes about 28-34 ATP- What is oxygen used for? o Final proton acceptor- What’s ATP synthase?o Enzyme that provides energy for the cell through the synthesis of ATPFermentation: glycolysis only- Lactic acid fermentationo Lactic Acid fermentation: 2 pyruvates  2 lactate- Alcohol fermentationo Alcoholic fermentation: 2 pyruvate  2 acetaldehyde  2 ethanol- What’s the same and different between fermentation and cellular respirationo Similar Glycolysis Use NAD+ as the oxidizing agento Different final acceptors Organic molecule in fermentation Oxygen in aerobic respiration Sulfur or nitrate in anaerobic respirationo Different ATP numbers Fermentation: 2 Respiration: