Chapter 2: Chemical Principles

State and explain the chemical bonds found in living organisms

• Ionic Bonds: attraction of opposite charges

• Covalent Bonds: sharing of electrons (strong bonds)

• Hydrogen Bonds: covalent bond, polarity

Unique properties of water

• Unequal charge distribution, polar solvent

• High boiling point (100 degrees C)

• Resists rapid changes in temperature

• Facilitates splitting/joining of H+ and OH-

** note: each water molecule can form up to 4 HB with other water molecules

What are the 4 major classes of organic molecules for life?

• Carbohydrates

• Lipids

• Proteins

• Nucleic Acids

Carbohydrates

• Large group of compounds (sugars and starches)

• Contain C, H, O

• Source of energy for cells

• Polar molecules (dissolve in water)

Types: Monosaccharides, disaccharides, polysaccharides

Ex. Glucose, Sucrose, Glycogen, Starch

Lipids

• Includes fats, complex lipids, steroids

• Essential for structure and function

• Used for energy storage

• Non-polar molecules (hydrophobic)

Fats

• Fatty acids

• “-cylgylceride”

• Saturated = no double bonds (solid @ room temp.)

• Unsaturated = double bonds (bent shape, liquid)

Phospholipids

• Contain glycerol, 2 fatty acids, phosphate group

• Phosphate group/head = polar (hydrophilic)

• Fatty acid tail = non-polar (hydrophobic)

• Form membranes in water

Biological membranes

• Made from a phospholipid bilayer

• Semi-fluid (saturated/unsaturated fatty acids)

• Separate watery inside of cell to water environment

Steroids

• hydrophobic 4 ring structure

• Found in eukaryotes

• Ex. Cholesterol

Proteins

• Made up of amino acids

• Contain C, H, O, N (sometimes S)

• Required for cell structure and function

• Act as enzymes

• At least 1 amino (-NH2) and 1 carboxyl (-COOH) group

• Chain of amino acids = polypeptide

Nucleic Acids

• DNA, RNA

Nucleotides are made up of:

• Nitrogenous Base

Purine: 2 rings = Adenine/Guanine

Pyrimidine : 1 ring = Thymine/Cytosine/Uracil

• Penrose/5C sugar

Ribose/Deoxyribose

• Phosphate

DNA/DNA structure

• Nitrogenous bases: A/G/T/C

• Sugar deoxyribose

• Double stranded

• Stores genetic info of all cellular organisms

• Strands built from a sugar phosphate backbone

• Strands held together by HBs between nitrogenous bases

• Forms the double helix

Base pairing: AT and GC

RNA

• Nitrogenous Bases: A/G/U/C

• Sugar ribose

• Single stranded

• Communicates instructions stored in DNA