BCMB 230 1st Edition Lecture 2 Outline of Last Lecture I.The BasicsII.HomeostasisIII.Feedback SystemsIV.Components of Homeostatic Control SystemsV.Processes Related to HomeostasisOutline of Current Lecture I.Chemical BondsII.MacromoleculesIII.Protein Structure and FunctionCurrent LectureChemical Bonds, Macromolecules, and Protein Structure/FunctionI. Chemical BondsIonic bond- strong attraction between two oppositely charged ions that leads to the transfer/exchange of electrons-Ion- an atom that gains or losses one or more electrons and acquires a net electrical charge -Cation-atom that lost an electron; a positively charged ion-Anion-atom that gained an electron; a negatively charged ionCovalent bond-chemical bond between two atoms in which each atom shares one of its electrons with the other-Nonpolar covalent bond- bond between atoms with similar electronegativities; electrons shared equally; lipid-soluble/lipophilic -Nonpolar molecules often found in lipid bilayers of the membranes of cells and intracellular organelles-Polar covalent bond- bond between atoms with different electronegativites; atoms at each end of the bond have an opposite electrical charge so electrons shared unequally; water-solube/hydrophilic (ex. readily dissolve in the blood, interstitial fluid, and intracellular fluid)-even though there is an uneven distribution of charge, there is no net charge for the bondThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Polarity is the most important thing to know about a molecule; it is critical to understand how something is going to react with the body; body is mostly made of water so polarity dictates transport capabilities and the ability to get into cells-Polar—is going to be water soluble; hydrophilic; lipophobic-Nonpolar-is going to be lipid soluble; hydrophobic; lipophillic-Hydrophilic-“water-loving”; attracted to and easily dissolved in water-Hydrophobic-“water-fearing”; not attracted to and insoluble in water-Amphipathic-“love both”; a molecule containing polar or ionized groups at one end and nonpolar groups at the other; have some solubility in both lipid and water; these molecules are mostly nonpolar with a small polar region-if you put amphipathic molecule in water it will tend to configure itself: polar portions associate with water on the outside, nonpolar portions associate onthe inside-can have a bilayer in order to keep the nonpolar areas happy (cell membrane has this structure)Electronegative-measure of an atom’s ability to attract electrons in a covalent bond-causes an uneven distribution of charges because electrons tend to spend more time orbiting the atom with higher electronegativity; leads to a polar molecule-generally increases as the total positive charge of a nucleus increases, but decreases as the distance between the shared electron and the nucleus increase-oxygen and nitrogen are very electronegativeHydrogen bonding- when the hydrogen atom in a polar bond in one molecule and an oxygen or nitrogen atom in a polar bond of another molecule attract each other and form a bond-a very weak bond-in large numbers, they play an important role in molecular interactions and in determining the shape of large moleculesVander Waals forces- attraction of nuclei of adjacent atoms; weak forces between atoms and molecules; -do not have to have chemical reaction to make or breakStrongest Bond to Weakest Bond: covalent—ionic—hydrogen—vanderwaalsII. MacromoleculesMain groupings: carbohydrates, lipids (fats), protein, nucleic acidsCarbohydrates-made of carbon, hydrogen, and oxygen-ex. glucose (C6H12O6)-simple sugar (also known as a monosaccharide); primarily used as an energy source-major monosaccharide in the body-Disaccharide-put simple sugars (monosaccharides) together-ex. glucose + fructose =sucrose (table sugar)-Polysaccharide-molecules that form when many monosaccharides are linked together to form polymers-ex. long chain of glucose molecules=glycogen-glycogen is the preferred source of energy for most cells; stored in muscles and liver-Starches-long chains of glucose made by plants; not created by humans but able to be digested and used for energy-Oligosaccharide-fairly short chain of sugars (monosaccharides); can play structural or signaling roles in the bodyLipids-molecules that are composed predominantly of carbon and hydrogen; have very low solubility in water-tend to be nonpolar-some lipids provide a valuable source of energy; others are a major component of all cellular membranes; others are important signaling molecules-Lipids can be divided into 4 subclasses:-(1) Fatty acid-long chain of carbons with carboxyl group (-COOH) at the end; number of carbons is always even (different kinds of fatty acids depending on the length of the chain); amphipathic molecule; fatty acids provide energy for cellular metabolism (break C-H bonds to release chemical energy that can be stored in the chemical bonds ofATP); extremely important source of energy-saturated fatty acid-no double bonds-unsaturated fatty acid-fatty acids that contain one or moe double bonds between carbon atoms-monounsaturated fatty acid-one double bond in an unsaturated fatty acid-polyunsaturated fatty acid-multiple double bonds in an unsaturated fatty acid- (2)Triglyceride (fat)-constitutes the majority of lipid in the body; important storage of energy for us (along with glycogen)-presence of fat and ability to store energy makes us weigh less-fats have over twice as much energy as glycogen-(3)Phospholipids- lipid with phosphate group attached of 3rd hydroxyl group of glycerol -important in cellular communication (signaling) and cell membrane structure-(4)Steroids-important in signaling/communication with molecules; consists of four interconnected carbon rings to which polar groups may be attached-Cholesterol-precursor to steroids; base used for steroids (rather than fatty acids) Proteins-“of the first rank”; large polymer consisting of one or more sequences of amino acid subunits joined by peptide bonds to form a functional molecule with multiple levels of structure-play critical roles in almost every physiological process; any physiological process shouldrelate to some protein that is responsible for it-can be broken down to an amino acid and used for energy or as chemical messengers for communication between cells (using amino acids and smaller