1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 2 Chemistry

2. Scientific study of substances (chemicals) and how they interact with each other The human body is made out of chemicals Processes of life are chemical interactions

3. 2.1 Atoms and Elements Matter is anything that has weight and occupies space Matter is composed of chemical elements

4. Chemical elements –Substances that cannot be broken down by chemical means into simpler substances Examples: carbon, hydrogen, nitrogen –92 naturally occurring –26 found in the human body

5. Atomic Structure –An atom is the smallest unit of an element that participates in chemical reactions –Atoms of the same element are similar –Atoms of different elements differ in size, weight, and how they interact with other atoms

6. –Atoms are composed of three subatomic particles Protons Neutrons Electrons –The overall electrical charge of an atom is neutral number of protons = number of electrons

7. 2.2 Molecules and Compounds A molecule is 2 or more atoms chemically combined –Examples: O 2, NaCl –Smallest unit of a chemical compound that exhibits the properties of the compound A chemical compound is a substance composed of 2 or more elements chemically combined in a fixed ratio

8. Chemical Formulas –Uses chemical symbols to express the chemical composition of a molecule –Example: H 2 O: 2 atoms of hydrogen, 1 atom of oxygen

9. Chemical Bonds –Force of attraction between 2 atoms that allows them to join and form a molecule –Atoms combine to fill their valence shells and become more stable –3 types of chemical bonds Ionic bonds Covalent bonds Hydrogen bonds

10. Ionic Bonds –Chemical bond formed between 2 ions with opposing electrical charge Anions Cations –Once a cation and anion are formed, the opposing electrical charges create a force that holds the ions together The force is the ionic bond!

12. –Ionic compounds dissociate when they dissolve in water Called electrolytes because they can conduct electrical current in water Composition and concentration of electrolytes must be kept within narrow limits for normal body function

13. Chemical Reactions –Occur when bonds between atoms form or break, yielding new combinations of atoms –Two main types of reactions Synthesis reactions Decomposition reactions –Many reactions are reversible

14. 2.3 Compounds Composing the Human Body Human body is made out of 2 types of compounds: Inorganic – do not contain both carbon and hydrogen Organic – contain both carbon and hydrogen

15. Major Inorganic Compounds Water –Composes 2/3 of body weight –Absorbs/releases large amounts of heat without much of a change in temperature –Solvent for many solutes –Site of chemical reactions in the body

16. Water –Serves as a lubricant –Assists in movement of food through the digestive tract –Water compartments in the body Intracellular fluid Extracellular fluid –Tissue (interstitial fluid) –Plasma –Lymph –Specialized fluids

17. Acids and Bases –Acids increase hydrogen ion concentration of a solution by releasing H + –Bases decrease the concentration of H + by combining with the H + already in the solution –pH is the measure of how basic or acidic a solution is

18. –pH Scale indicates the acidity or alkalinity of a solution (relative concentrations of H+ and OH-) Ranges from 0-14 pH 7 is neutral, meaning equal H+ and OH- concentrations >pH 7 is a base; higher number means stronger base <pH 7 is an acid; lower number means stronger acid

20. –Buffers Chemical or chemicals that can either pick up or release H + to keep a solution’s pH constant Maintain normal PH of body fluids Needed because slight pH changes can be harmful to body cells

21. Salts –Ionic compounds that dissociate in water but do not produce H + or OH - ions Example: NaCl dissociates to Na + and Cl - –Provide ions essential for normal body functioning –Example of salts: sodium, potassium, calcium salts

22. Major Organic Compounds Carbohydrates –Formed of carbon, oxygen, and hydrogen 2 H for every O –Primary source of nutrient energy for body cells –Classified by molecular size Monosaccharides- ex. glucose Disaccharides- Polysaccharides

23. –Monosaccharides or simple sugars Simplest carbohydrates Glucose (C 6 H 12 O 6 ) is major fuel for cells Fructose and galactose are 6-C simple sugars found in foods

24. –Disaccharides Formed by chemically combining 2 monosaccharides Maltose Sucrose Lactose

25. –Polysaccharides Formed by chemically combining many monosaccharides Glycogen: animal carbohydrate storage Starch: plant carbohydrate storage

26. Lipids –Consist of carbon, hydrogen, and oxygen atoms C atoms form backbone of molecules Many more H atoms then O atoms –Most abundant in the body are Triglycerides Phospholipids Steroids

27. –Triglycerides Most concentrated energy source in the body Around internal organs and under the skin Hydrophobic One glycerol molecule and 3 fatty acid molecules joined together

28. Saturated fats –Animal triglycerides or fats –All C-C bonds are single bonds –Solid at room temperature –Examples: butter, lard Unsaturated fats –Plant triglycerides or oils –One or more double C-C bonds –Monounsaturated –Polyunsaturated –Examples: olive oil, corn oil

29. –Phospholipids Composed of 1 glycerol, 2 fatty acid, and 1 phosphate group Hydrophilic Major components of cell membranes

30. –Steroids Molecules containing 4 C rings Cholesterol, a steroid and cell component, is used to make other steroids

31. Proteins –Amino acids are the building units of proteins Composed of carbon, hydrogen, oxygen, and nitrogen Consist of an amine group, acid group, and R group 20 different types of amino acids, each different in their R group

32. –Amino acids are joined by peptide bonds Dipeptide Polypeptide –Each polypeptide or protein has a unique three-dimensional shape –Classification of proteins Structural Functional

33. –Enzymes are proteins One enzyme catalyzes one particular chemical reaction Aid in the conversion of a substrate into a product Loss of an enzyme’s specific 3-D structure inactivates it

34. Nucleic Acids –Two types in cells Deoxyribonucleic acid (DNA)- stores genetic information Ribonucleic acid (RNA)- involved in protein synthesis –Building blocks are called nucleotides Composed of 1 C 5 sugar, 1 phosphate, 1 organic base

35. Adenosine Triphosphate (ATP) –Modified nucleotide with adenosine and 3 phosphates –Temporarily stores energy extracted from nutrients by cells –Only molecule to provide immediate energy to keep cellular processes going (powers chemical reactions)