Chapter 2: Chemistry

Chapter 2 Chemistry: the science that deals with the structure of matter Matter: anything that takes up space and has mass Mass: the amount of material in matter Atoms: the smallest units of matter composed of subatomic particles Subatomic particles: protons (+) neutrons (/) and electrons (-) Elements: pure substances composed of only one type of atom Isotope: atoms of the same element whose nuclei contain different numbers of neutrons Electron shells · The first energy level holds 2e- and the second and third levels hold 8 Valence shell: the outermost energy level ↳ unfilled valence shells are unstable and reactive Chemical Bonds Free radicals Molecule: any chemical structure with covalent bonds (shared electrons) Compound: a pure substance made up of atoms of two or more different elements ① Ionic Bonds · ions: an atom or group of atoms that have an electrical charge (cation vs. anion) ↳ atoms become ions by gaining or losing electrons (also called ionization) · ionic bonds occur when there is an electron transfer to another atom ② Covalent Bonds · covalent bonds are strong bonds created by the sharing of electrons · They can be single, double, or triple covalent bonds based on amount of electrons shared · Free radicals: an atom, ion, or molecule that contains unpaired electrons in their valence shell. ↳ highly reactive · Non-polar bonds involve equal sharing of electrons · Polar bonds involve unequal sharing of electrons, which changes the shapes of molecules and causes charged ends ③ Hydrogen Bonds · Hydrogen bond: the attraction between a slight positive charge on the hydrogen atom is attracted to the slight negative charge on another atom (oxygen, nitrogen, fluorine) · Hydrogen bonds are too weak to create molecules, but they can change the shapes or pull molecules closer together ↳ surface tension The Importance of Water · Makes up 2/3 of total body weight · Universal Solvent · Reactivity - active component in hydrolysis and dehydration synthesis · High heat capacity · Lubricant · Polar molecule Solute: the substance being dissolved Solvent: the dissolving medium (often its water) Solution: a homogenous mixture of one or more solutes dissolved in a solvent Solubility: the ability to be dissolved Hydrophilic: molecules that interact readily with water Hydrophobic: molecules that do not readily interact with water Electrolytes: soluble inorganic substances whose ions will conduct an electrical current in solution (water) ↳ importance of fluid and electrolyte balance in body ↳ Kidneys, digestive tract, and skeletal system help regulate fluid and electrolytes Acids: electrolytes that dissociates in solution and releases hydrogen ions ↳ proton donor Bases: electrolytes that removes hydrogen ions from solution ↳ proton acceptor PH · pH is a measure of the concentration of hydrogen ions · 0-14 · neutral: PH = 7 · acidic: PH = < 7 · basic/alkaline: PH = > 7 Acidosis: blood PH < 7.35 Alkalosis: blood PH > 7.45 Normal blood PH is 7.35 - 7.45 Buffers: compounds that stabilize the PH of a solution by replacing hydrogen ions (Sodium bicarbonate) Macromolecules Types of macromolecules: contain carbon atoms. Each have different structures and properties ② Lipids Macromolecules: molecules that are synthesized by living organisms and ↳ Dehydration synthesis reactions join monomers to create polymers ↳ Hydrolysis reactions separate polymers back into monomers ① Carbohydrates ③ Proteins ④ Nucleic Acids 1. Carbohydrates ↳ carbohydrate: an organic molecule that contains carbon, hydrogen, and oxygen in a ratio near 1: 2: 1 ↳ carbohydrates act as an energy source for the body ↳ monosaccharides (simple sugars): a carbohydrate with 3-7 carbon atoms such as glucose C6H12O6 ↳ disaccharides: two monosaccharide monomers joined together ↳ polysaccharides: when repeated dehydration synthesis occurs · examples: cellulose, starches, glycogen Isomers: molecules with the same molecular formula but different structures 2. Lipids ↳ lipids: contain carbon, hydrogen, and oxygen, but only a 1:2 ratio for carbon and hydrogen, and LOTS of oxygen ↳ provide twice as much energy as carbohydrates, but also used for communication, insulation, and protection ↳ not soluble in water ↳ include: fatty acids, eicosanoids, glycerides, steroids, phospholipids and glycolipids 3. Proteins Cholesterol* ↳ proteins: organic polymers that consist of long chains of amino acids · amino acids are joined by peptide bonds. They are then called peptides which combine in chains to create polymers ↳ important for support, movement, transport, buffering, metabolic regulation, coordination and control, and defense ↳ includes: hemoglobin, collagen, keratin, antibodies, and enzymes 4. Nucleic Acids ↳ nucleic acid: large organic molecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus ↳ made of nucleotides (monomer) · each nucleotide contains a pentose, a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine, uracil) · adenine and guanine are double-ringed purines, and the others are single-ringed pyrimidines (A-T, C-G) complimentary base pairs ↳ responsible for genetic information ↳ 2 classes of nucleic acid: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) Enzymes · enzyme: a substance which acts as a catalyst to bring about a specific biochemical reaction · Each enzyme acts on a specific substrate and use the suffix -ase · Basic characteristics of enzymes: ↳ Specificity: catalyzes only one type of reaction ↳ saturation limits: substrate concentration only speeds them to a set point ↳ regulation: anything that changes the shape of an enzyme can turn it on or off · cofactor: an ion or molecule that must bind to an enzyme before substrates can bind · coenzyme: nonprotein organic molecules that function as cofactors ATP and Cellular Energy · Phosphorylation: the process of attaching a phosphate group to another molecule ↳ Quick energy is released when one phosphate group is removed from ATP ↳ adding more phosphates creates high energy compounds · Energy storage -> ADP is converted to ATP · Energy release -> ATP is converted to ADP · Breakdown of ATP often requires an enzyme called ATPase · ATP can be created both aerobically and anaerobically (aerobically is better)