Week 2 Lecture Notes - University of Newcastle

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COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of the University of Newcastle persuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice Chemical Bonds & Shapes HUBS 1403 Biomedical Science Part 1 Sticking Atoms Together  Chemical Bonds l Consider three types: l hydrogen bonds (weak) l ionic bonds (strong) l covalent bonds (very strong) l Each type of bond has a different strength which allows different interactions to occur  Ionic Bonds l chemical bonds created by the electrical attraction between cations (+ve) and anions (-ve)  Covalent Bonds l Some atoms complete their outer shells by sharing electrons Double Covalent Bond Triple Covalent Bond Types of Covalent Bonds l Non polar l electrons are shared equally l the atoms remain electrically neutral l very strong l Polar l unequal sharing of electrons l the atoms have slight +ve or –ve charge l E.g. water 8 Chemical Bonds - Summary https://youtu.be/_M9khs87xQ8 School of Biomedical Science and Pharmacy Slide 9 Faculty of Health Chemical Bonds & Shapes HUBS 1403 Biomedical Science Part 1 Aqueous solutions Aqueous solutions School of Biomedical Science and Pharmacy Slide 11 Faculty of Health Our existence depends upon water l Makes up 2/3 of total body weight l Solvent l Provides a medium for solutes l Reactivity l Hydrolysis & dehydration reactions l High heat capacity l Extreme temps required for phase transition l Cooling effect of perspiration l Thermal inertia l Lubrication 12 Activities of Water Molecules in Aqueous Solutions Inorganic Organic 13  Hydrophilic Compounds l Organic molecules with polar covalent bonds l Attract water molecules l Formation of hydration spheres carry molecules into solution i.e. soluble l E.g. glucose  Hydrophobic Compounds l Organic molecules with few or no polar covalent bonds l No +ve or –ve terminals i.e. non-polar l Do not interact with water l Do not form hydration spheres i.e. insoluble 15  Measuring Quantities Mole = quantity (in grams) equal to that substances atomic or molecular weight Avagadro’s Number n 1 mole of O atoms: (6.023 x 1023) ¨ weighs 15.999g = the number of atoms in 1 mole of any chemical ¨ contains 6.023 x 1023 O atoms substance n 1 mole of glucose C6H12O6 molecules: C H O ¨ weighs (6x12g) + (1x12g) + (6x16g) = 180g ¨ contains 6.023 x 1023 molecules of C6H12O6 Measuring Concentrations Slide School18 of Biomedical Science and Pharmacy Faculty of Health Some Normal Plasma Levels in Adults Calcium 2.12 - 2.62 mmol/L 8.5 – 10.5 mg/100mL Chloride 97-106 mmol/L 97 – 106 mEq/L Cholesterol 3.6 - 6.7 mmol/L 140 - 260 mg/100mL Glucose 3.5 - 8 mmol/L 63 - 144 mg/100mL Potassium 3.3 - 4.7 mmol/L 3.3 – 4.7 mEq/L Sodium 135-143 mmol/L 135-143 mEq/L mmol = millimole = 1/1,000 of a mole i.e. one thousandth of a mole μmol = micromole = 1/1,000,000 of a mole i.e. one millionth of a mole Calculation question The molecular weight of glucose is 180.16g. l How much glucose is required to make 1 litre of a 5mM glucose solution? l How much glucose is required to make 1 litre of a 0.5% glucose solution?  Electrolytes l soluble inorganic molecules whose ions will conduct an electrical current in solution +ve -ve Cl- Na+ NaCl Glucose Important Electrolytes that dissociate in Body Fluid Electrolyte Ions Released Concentrations must be NaCl Na+ + Cl- maintained in homeostasis by kidneys, digestive tract KCl K+ + Cl- and skeletal system CaHPO4 Ca2+ + HPO42- e.g. [K+] weak irregular heartbeat NaHCO3 Na+ + HCO3- [K+] general muscular MgCl2 Mg2+ + 2Cl- paralysis Na2HPO4 2Na+ + HPO42- Na2SO4 2Na+ + SO42-  Acid Base Balance The acid base balance of blood and extracellular fluid is tightly regulated. pH (the concentration of hydrogen ions) must remain close to neutral for all the enzymes and other molecules that keep cells alive to work properly. School of Biomedical Science and Pharmacy Slide 22 Faculty of Health Inorganic Acids, Bases & Salts l Dissociate into ions in solution Hydrogen Ions in Body Fluids l extremely reactive in solution. l [H+] ↑ will l break chemical bonds l change the shapes of complex molecules l disrupt cell and tissue functions l Therefore, [H+] or pH must be carefully regulated Hydrogen Ions Are Present in Water H2O ! H+ + OH- l One litre of pure water l Contains ~ 0.0000001 moles of hydrogen ions l i.e. [H+] = 1 x 10-7 moles/litre l The negative logarithm of [H+] is 7 l Therefore the pH of pure water is 7  pH Values l When pH = 7: l solution is neutral l an equal number of H+ ions and OH- ions l When pH < 7: l solution is acidic l more H+ than OH- l When pH >7: l solution is alkaline l more OH- than H+  pH Scale l Remember the pH scale is l logarithmic i.e. a change of 1 pH unit is a ten- fold change l Inverted i.e. a solution with pH 6 has 10x more H+ than a solution with pH 7 27 True or False? l Acids are referred to as proton donors l A pH of 10 is 100 times more basic (alkaline) than a pH of 8 l A pH of 4 is ten times more acidic than a pH of 3 l Buffers can accept H+ from solution l Buffers can donate H+ to the solution  Hydrogen Ions in Blood l Normal pH of blood: 7.35 - 7.45 l Blood pH < 7.35 = acidosis l More common clinically l CNS & cardiac function deteriorate l pH 7.45 = alkalosis l Uncontrollable skeletal muscle contractions →coma l Homeostasis must be maintained by buffer systems l Weak acid and its related salt (functions as weak base) e.g. carbonic acid-bicarbonate system 29 Carbonic Acid – Bicarbonate Buffer System Response to rise in pH H2CO3 HCO3- + H+ Response to drop in pH Carbonic Acid Bicarbonate ion Proton H+ donor H+ acceptor (weak acid) (weak base) 30 Maintaining Acid-Base Balance l Lungs l Carbonic acid-Bicarbonate buffer l Other buffer systems l Protein, phosphate l Kidneys ………but more about that in HUBS1404 31 1  Introduction to Carbohydrates & Lipids HUBS 1403 Biomedical Science Part 1 Metabolism  Metabolism l all the chemical reactions occurring in cells and tissues of your body at any moment ¨ provide the energy needed to maintain homeostasis, also growth, maintenance and repair, secretion and contraction n Cells remain alive by controlling the types and rates of chemical reactions Energy Transfer in Chemical Reactions l Exergonic reactions l release more energy than they absorb l Endergonic reactions l Absorb more energy than they release Which graph represents an exergonic reaction? Coupling of Reactions l energy released from an exergonic reaction often used to drive an endergonic reaction Three Types of Chemical Reactions 1. Decomposition or catabolism 2. Synthesis or anabolism 3. Exchange or displacement 6 Decomposition Reactions Synthesis Reactions 8 Exchange Reactions 9 Reversible Reactions  Catalysts l Speed up chemical reactions by lowering the activation energy l Enzymes are catalysts 11 Classes of Organic Compounds l Carbohydrates l Lipids l Proteins l Nucleic acids l High energy compounds e.g. ATP 12 Functional Groups 13  Introduction to Carbohydrates & Lipids HUBS 1403 Biomedical Science Part 1 Carbohydrates  Carbohydrates l Contain C, H, O in a ratio ~ 1:2:1 l Include the sugars and starches l