Chapter 2: Chemicals of Life

A. Bonding 1. Covalent Bonds 2 or more atoms share electrons to form a molecule No net charge due to equal number of + and – Ex. water

Covalent bonding vs. Hydrogen bonding Properties of Water Covalent bonding vs. Hydrogen bonding Hydrogen Bond Covalent Bond

A. Bonding 2. Hydrogen Bonds Weak bond between polar molecules

A. Bonding 3. Ionic Bonds Gained or lost one or more electrons Charged due to unequal number of electrons or protons Ex. NaCl

B. Properties of Water 1. High Heat Capacity Water heats slow Retains heat longer Helps maintain homeostasis

Water is the solvent of Life! B. Properties of Water 2. Universal Solvent Water is the solvent of Life! Solute – substance dissolved in a solvent to form a solution Solvent – fluid that dissolves solutes Example: Ice Tea – water is the solvent and tea and sugar the solutes

3. Cohesion, Adhesion and Surface Tension B. Properties of Water 3. Cohesion, Adhesion and Surface Tension a. cohesion = water attracted to other water molecules because of polar properties ex. Forms drops or film surface tension = water is pulled together creating the smallest surface area possible b. adhesion = water attracted to other materials ex. Getting wet, capillary action

B. Properties of Water 4. Capillary Action = Water molecules move due to adhesive and cohesive properties as a result of the original adhesion. Ex: Think water in a straw Ex: Water moves through trees this way

B. Properties of Water 5. Water is a polar molecule. Many substances will dissolve Non-polar molecules will not dissolve

C. Classes of Organic Molecules: What are the four classes of organic molecules? Carbohydrates Lipids Proteins Nucleic Acids

1. Carbohydrates Sugars Carbo = carbon, hydrate = water; Oxygen Functions: Store energy in chemical bonds Glucose is the most common monosaccharide Monosaccharides Disaccharides Polyshaccharides

1. Carbohydrates Benedicts Test

1. Carbohydrates Iodine Starch test

2. Lipids Structure: Greasy or oily nonpolar compounds Functions: Energy storage membrane structure Protecting against drying out. Insulating against cold. Absorbing shocks.

2. Lipids Saturated and Unsaturated Fats liquid at room temp one or more double bonds between carbons in the fatty acids allows for “kinks” in the tails most plant fats Saturated fats: have only single C-C bonds in fatty acid tails solid at room temp most animal fats

2. Lipids. Phospholipids Structure: Glycerol + 2 fatty acids + phosphate group. Function: Main structural component of membranes, where they arrange in bilayers.

3. Proteins Structure: Polypeptide chains Consist of peptide bonds between 20 possible amino acids Have a 3 dimensional globular shape

3. Functions of Proteins Enzymes speed up a chemical reaction Structural materials keratin (the protein found in hair and nails) collagen (the protein found in connective tissue) Specific carriers – Carry materials across cell membrane, carry oxygen in blood

3. Proteins: Structure of Amino Acid Hydrogen Amino group Carboxyl (acid) group Variable R group specific to each amino acid

4. Nucleic Acids Two kinds: DNA: RNA: double stranded can self replicate makes up genes which code for proteins is passed from one generation to another RNA: single stranded functions in actual synthesis of proteins coded for by DNA is made from the DNA template molecule