Overview Chemistry Lecture 2 Energy The capacity to do work (put matter into motion) Types of energy { { Kinetic – energy in action Potential – energy of position; stored (inactive) energy Energy is easily converted from one form to another During conversion, some energy is “lost” as heat Elements vs. Molecules Elements are atoms of one particular type (from the periodic table) Molecules are groups of atoms that contain more than one element Energy and matter Atoms, molecules, and chemical bonds Importance of organic and inorganic nutrients and metabolites Structure and function of carbohydrates, lipids, proteins, and nucleic acids Enzymes and ATP help run the metabolic reactions of the body Why is chemistry important to anatomy and physiology? Chemistry is the science that deals with matter Matter is anything that takes up space and has mass Smallest stable units of mass are atoms Elements found in the body 13 principal elements { { { { { Oxygen (O) Carbon (C) Hydrogen (H) Nitrogen (N) Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe) 13 trace elements { (e.g. zinc, manganese) 1 Elements with unfilled electron shells are reactive To become stable they form chemical bonds. Three main types of chemical bonds { Intramolecular: { Ionic bonds (charged atoms resulting from the gain or loss of electrons) Covalent bonds (electrons are shared) Ionic and covalent bonds Molecules: atoms held together by covalent bonds Salts: molecules held together by ionic bonds Q: What are the strongest type of bonds? Intermolecular Hydrogen bonds Importance of water Water properties The body is mostly water (~2/3rds of total body weight) so all chemical reactions in the body occur in water Covalent bonds are much stronger than ionic bonds in water Water properties Water can dissolve organic and inorganic molecules making a solution Water is needed for chemical reactions Water can absorb and retain heat Water is an effective lubricant Hydrogen bonds: weak bonds between molecules Water has all these amazing properties due to their ability to form hydrogen bonds 2 Mixtures and Solutions Mixtures – two or more components physically intermixed (not chemically bonded) { { { Solutions – homogeneous mixtures of components Colloids (emulsions) – heterogeneous mixtures whose solutes do not settle out Suspensions – heterogeneous mixtures with visible solutes that tend to settle out Essential Molecules Nutrients: { essential molecules obtained from food (you have to eat them to get them) Metabolites: { molecules made or broken down in the body Organic vs. inorganic Vitamins and Minerals Organic molecules: Always contain carbon with hydrogen, and sometimes oxygen Often soluble in water Inorganic: Electrolytes, minerals, and compounds that do not contain carbon with hydrogen. Important examples: oxygen, carbon dioxide, water, inorganic acids and bases, salts Vitamins Minerals Organic substances necessary for metabolism There are 13 known vitamins (e.g. A, B1, D, K) Some are fat soluble while others are water soluble Are Coenzymes that help carry out the reactions of metabolism Vitamins and minerals are essential nutrients that are required in very small amounts for healthy growth and development. Examples? They cannot be synthesized by the body and are essential components of the diet. Inorganic compound (often salts or elements) necessary for proper body function Can be bulk or trace minerals Are Cofactors in metabolic reactions 3 Electrolytes Electrolytes Inorganic ions (usually minerals) that conduct electricity in solution Electrolyte balance is maintained in all body fluids; imbalance seriously disturbs vital body functions Table 2–3 Biological Macromolecules 1. Carbohydrates Life depends on four types of organic macromolecules: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids Contain carbon, hydrogen and oxygen in a ratio of 1:2:1 Account for less that 1% of body weight Used as energy source Called saccharides Can you think of an example of each? Glucose is a monosaccharide Disaccharides Sucrose Lactose 4 Polysaccharides Polysaccharides Starch Glycogen Cellulose All are long strings of glucose molecules Difference lies in how they are bonded together PLAY Polysaccharides or polymers of simple sugars Polysaccharides Figure 2.14c Polymers A polymer is any molecule made up of several repeating units. Starch is a polymer of glucose. 2. Lipids Lipids: Triglycerides (Fats and Oils) Consist of 3 fatty acids and glycerol { { { Insulation Energy protection Contain carbon, hydrogen, and oxygen but the ratio of C:H is 1:2 (much less O) May also contain other elements, phosphorous, nitrogen, and sulfur Form essential structures in cells Are important energy stores Lipids: Steroids and Cholesterol All consist of a complex ring structure Q: What ‘s the difference between saturated and unsaturated? 5 Lipids: Phospholipids 3. Proteins Amphipathic Protein Structure Proteins are the most abundant and important organic molecules Basic elements: { carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) Basic building blocks: { 20 amino acids Consist of chains of amino acids liked together by peptide bonds Enzymes are proteins Protein Structure – 4 levels Primary: amino acid sequence Secondary: Hydrogen bonds form spirals or pleats Tertiary: Secondary structure folds into a unique shape Quaternary: several tertiary structures together Figure 2–20a Protein structure Shape and Function Protein function is based on shape Shape is based on sequence of amino acids Denaturation: { loss of shape and function (due to heat, pH change or other factors) 6 Protein Functions { { { support: structural proteins movement: contractile proteins transport: transport proteins Proteins: Enzymes { { { { buffering: regulation of pH metabolic regulation: enzymes coordination and control: hormones defense: antibodies Activation Energy Enzymes are catalysts: { { proteins that lower the activation energy of a chemical reaction are not changed or used up in the reaction Other factors that speed up reactions: { { { Increased temperatures Smaller particles Higher concentrations Characteristics of Enzymes Chemical reactions in cells cannot start without help Activation energy gets a reaction started Figure 2–7 Energy In, Energy Out Exergonic reactions: { produce more energy than they use Endergonic reactions: { Figure 2.20 KEY CONCEPT Most chemical reactions that sustain life cannot occur unless the right enzymes are present use more energy than they produce 7 Active site Amino acids How Enzymes Work Substrates: { reactants in enzymatic reactions Active site: { + How Enzymes Work Substrates (S) Enzyme (E) Enzyme-substrate complex (E-S) H2O Free enzyme (E) a location on an enzyme that fits a particular substrate Peptide bond Internal rearrangements leading to catalysis Figure 2–21 Dipeptide product (P) 4. Nucleic acids Structure of DNA Contain C, H, O, N, and P DNA and RNA are nucleic acids Nucleotide consists of { { { Sugar Phosphate group Nitrogenous base Figure 2.22b Membrane protein Pi P A nucleotide: ATP Solute Energy storage for cells Many enzymes use ATP Provides a way to run reactions that are otherwise endergonic (require energy) ATP is the energy currency of the cell Solute transported (a) Transport work ADP + Pi ATP Relaxed smooth muscle cell Contracted smooth muscle cell (b) Mechanical work Pi X P X Y + Y Reactants Product made (c) Chemical work Figure 2.24 8 Compounds Important to Physiology Summary Energy and matter Atoms, molecules, and chemical bonds Importance of organic and inorganic nutrients and metabolites Structure and function of carbohydrates, lipids, proteins, and nucleic acids Enzymes and ATP help run the metabolic reactions of the body Table 2–8 9