Matter: Atoms and Molecules Smallest unit of an element Subatomic particles Protons: (+) charge Neutrons: neutral Electrons: (-) charge Figure 2-1

Matter: Atoms and Molecules Structure of atom Electrons surround nucleus Electrons organized in shells The outer shell determines chemical properties

Matter: Atoms and Molecules Key Note All matter is composed of atoms in various combinations. Their interactions establish the foundations of physiology at the cellular level.

Matter: Atoms and Molecules Ionic Bonds Atoms gain or lose electrons Charged atoms are ions Ions bear (+) or (-) charge Cations have (+) charge Anions have (-) charge Cations and anions attract Ions form bonds

Matter: Atoms and Molecules Table 2-2

Chemical Reactions Metabolism All the chemical reactions in the body Consumes reactants Produces products Breaks or makes chemical bonds between atoms

Chemical Reactions Basic Energy Concepts Potential energy—stored energy E.g., glycogen stored in muscle cells Kinetic energy—energy of movement E.g., leopard pounces on prey

Inorganic Compounds Nutrients Essential elements and molecules obtained from the diet Metabolites Molecules synthesized or broken down by chemical reactions inside the body

Inorganic Compounds Inorganic Smaller molecules such as water, oxygen and ions that lack carbon and hydrogen Organic Larger molecules such as sugars, proteins, and fats composed largely of carbon, hydrogen and oxygen

Human Body Composition Element Percent by mass Oxygen 65 Carbon 18 Hydrogen 10 Nitrogen 3 Calcium 1.5 Phosphorus 1.2 Potassium 0.2 Sulfur Chlorine Sodium 0.1 Magnesium 0.05 Iron, Cobalt, Copper, Zinc, Iodine <0.05 each Selenium, Fluorine <0.01 each

Organic Compounds Carbohydrates Most important energy source for metabolism Three major types Monosaccharides (E.g., glucose) Disaccharides (E.g., sucrose) Polysaccharides (E.g., glycogen)

Organic Compounds Glucose Figure 2-10

Organic Compounds Formation of Glycogen Figure 2-11(c)

Organic Compounds Lipids Water-insoluble Four important classes Fatty acids Fats Steroids Phospholipids

Organic Compounds Fatty Acids Figure 2-12

Organic Compounds Cholesterol Building block for steroid hormones Component of cell membranes Figure 2-14

Organic Compounds Proteins Most abundant organic component in human body About 100,000 different proteins Contain carbon, nitrogen, oxygen, hydrogen, and a bit of sulfur

Organic Compounds Proteins play vital roles Support Movement Transport Buffering Regulation Defense

Organic Compounds Proteins are built from amino acids Figure 2-16(a)

Protein Structure Figure 2-17

Organic Compounds Enzyme Function Substrates (reactants) bind to active site on enzyme surface Binding lowers activation energy needed for reaction Substrates react to form product Product is released from enzyme surface

Enzyme function made simple Figure 2-18

Organic Compounds Nucleic Acids Large molecules Built from atoms of C, H, O, N, and P Store and process molecular information Two classes of nucleic acid DNA (deoxyribonucleic acid) RNA (ribonucleic acid)

The Structure of Nucleic Acids Figure 2-19ab

The Structure of Nucleic Acids

Organic Compounds Structure of Nucleic Acids Nucleotides contain a sugar, a phosphate, and a base Sugar-phosphate bonds link nucleotides in long strands Hydrogen bonds hold two DNA strands in a double helix

Summary of Body Chemistry Organic Chemical Building Blocks Figure 2-22