Chapter 2 - Chemicals and the body. This chapter presents the following content: From atoms to molecules, water and living things, molecules of life, carbohydrates, lipids, proteins, nucleic acids. | Chapter 2 Biology 25: Human Biology Prof. Gonsalves Los Angeles City College Loosely Based on Mader’s Human Biology,7th edition I. Elements: Substances that can not be broken down into simpler substances by chemical reactions. There are 92 naturally occurring elements: Oxygen, carbon, nitrogen, calcium, sodium, etc. Life requires about 25 of the 92 elements Chemical Symbols: Abbreviations for the name of each element. Usually one or two letters of the English or Latin name of the element First letter upper case, second letter lower case. Example: Helium (He), sodium (Na), potassium (K), gold (Au). Main Elements: Over 98% of an organism’s mass is made up of six elements. Oxygen (O): 65% body mass Cellular respiration, component of water, and most organic compounds. Carbon (C): 18% of body mass. Backbone of all organic compounds. Hydrogen (H): 10% of body mass. Component of water and most organic compounds. Nitrogen (N): 3% of body mass. Component of proteins and nucleic acids (DNA/RNA) Calcium (Ca): of body mass. Bones, teeth, clotting, muscle and nerve function. Phosphorus (P): 1% of body mass Bones, nucleic acids, energy transfer (ATP). Minor Elements: Found in low amounts. Between 1% and . Potassium (K): Main positive ion inside cells. Nerve and muscle function. Sulfur (S): Component of most proteins. Sodium (Na): Main positive ion outside cells. Fluid balance, nerve function. Chlorine (Cl): Main negative ion outside cells. Fluid balance. Magnesium (Mg): Component of many enzymes and chlorophyll. Trace elements: Less than of mass: Boron (B) Chromium (Cr) Cobalt (Co) Copper (Cu) Iron (Fe) Fluorine (F) Iodine (I) Manganese (Mn) Molybdenum (Mo) Selenium (Se) Silicon (Si) Tin (Sn) Vanadium (V) Zinc (Zn) II. Structure & Properties of Atoms Atoms: Smallest particle of an element that retains its chemical properties. Made up of three main subatomic particles. Particle Location Mass Charge Proton (p+) In nucleus 1 +1 Neutron (no) In nucleus 1 0 Electron . | Chapter 2 Biology 25: Human Biology Prof. Gonsalves Los Angeles City College Loosely Based on Mader’s Human Biology,7th edition I. Elements: Substances that can not be broken down into simpler substances by chemical reactions. There are 92 naturally occurring elements: Oxygen, carbon, nitrogen, calcium, sodium, etc. Life requires about 25 of the 92 elements Chemical Symbols: Abbreviations for the name of each element. Usually one or two letters of the English or Latin name of the element First letter upper case, second letter lower case. Example: Helium (He), sodium (Na), potassium (K), gold (Au). Main Elements: Over 98% of an organism’s mass is made up of six elements. Oxygen (O): 65% body mass Cellular respiration, component of water, and most organic compounds. Carbon (C): 18% of body mass. Backbone of all organic compounds. Hydrogen (H): 10% of body mass. Component of water and most organic compounds. Nitrogen (N): 3% of body mass. Component of proteins and nucleic acids (DNA/RNA)
