Elements are the building blocks for all matter. Elements contain a single type of atom; elements cannot be further broken down by a chemical reaction. Elements important for the purposes of this course include hydrogen, oxygen, nitrogen, and carbon. All naturally occurring elements are listed in the periodic table.

Why water is important to the human body Chemical Properties Universal solvent: Water can dissolve hydrophilic (water-loving) substances such as proteins, gases, salts, and carbohydrates and transport them inside the cells, in and out of cells, and between different cells. It cannot dissolve hydrophobic (water-fearing) substances. Chemically active: Water can participate in many chemical reactions. Physical Properties Heat transfer: Water remains a liquid over a wide range of temperatures and conducts heat well. Think of a pot of water on the stove—only the water at the bottom of the pot is in contact with the heat source yet all of the water is heated. Water (in blood) is necessary for cooling or warming purposes throughout the body.

Chemical Bonds Atoms interact chemically to alter neutrality of atoms and form bonds.

Ionic bonding.

Ionic Bonds Electrons transferred between atoms form ionic bonds. Electrolytes— ionic bonds form compounds that release ions when they are in solution –Influence homeostasis (stable condition of normal organism) –Conduct electronic current

Covalent Bonds A chemical bond in which atoms share electrons Non-polar covalent bond Polar covalent bond

Compounds: Acids, Bases, and Salts Compounds are chemical substances with specific properties Acid can donate hydrogen ion (H+) Base (alkali) can accept hydrogen ion (H+) Salt is formed by a reaction between an acid and a base

The pH Scale Represents relative concentrations of hydrogen and hydroxide ions in a solution Scale from 0 (most acidic) to 14 (most basic) Each unit represents a 10-fold change Body fluids usually pH

Buffers Chemicals that prevent sharp changes in hydrogen ion concentration and maintain relatively constant pH in body fluids

Checkpoint 2-8: The pH scale is used to measure acidity and alkalinity of fluids. What number is neutral on the pH scale? What kind of compound measures lower than this number? Higher? Checkpoint 2-9: What is a buffer?

Chemistry of Living Matter Living matter contains 26 of 92 natural elements. 96% of body weight—four elements 4% of body weight—nine elements 0.1% of body weight—13 elements

Organic Compounds Chemical compounds that characterize living things Contain carbon, hydrogen, and oxygen –Carbohydrates –Lipids –Proteins

Question: True or False?: The three main organic compounds are carbohydrates, proteins, and amino acids.

Answer: False: The three main organic compounds are carbohydrates, proteins, and lipids

Carbohydrates Monosaccharides (simple sugars) –Glucose Disaccharides Polysaccharides –Starch –Glycogen

Examples of carbohydrates. ZOOMING IN: What are the building blocks of disaccharides and polysaccharides?

Lipids Triglycerides –Glycerol (glycerin) Phospholipids Steroids –Cholesterol –Steroid hormones –Sex hormones

Proteins Amino acids Enzymes –Catalysts –Substrates

Proteins. ZOOMING IN What part of an amino acid contains nitrogen?

Diagram of enzyme action. ZOOMING IN How does the shape of the enzyme before the reaction compare with its shape after the reaction?

Checkpoint 2-13: Enzymes are proteins that act as catalysts. What is a catalyst?

End of Presentation