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

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

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

A. BondingBonding 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 a.Water heats slow b.Retains heat longer c.Helps maintain homeostasis 1. High Heat Capacity

B. Properties of Water 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 2. Universal Solvent

B. Properties of Water 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 3. Cohesion, Adhesion and Surface Tension

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 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: 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