The Molecules of Cells Chapter Three

Classes of Compounds Inorganic compounds Organic compounds Water, salts, and many acids and bases Do not contain carbon Organic compounds Carbohydrates, fats, proteins, nucleic acids Contain carbon, usually large, covalently bonded Life’s molecular diversity is based on the properties of carbon

Macromolecules There are four important macromolecules (organic compounds) in the body: Carbohydrates, Lipids, Proteins, Nucleic acids Three of these macromolecules are Polymers Polymers = chain-like molecules consisting of many similar/identical building blocks (monomers) Linked by covalent bonds Organic compounds that are Polymers = Carbohydrates, Proteins, Nucleic acids

Cells Make and Break Polymers Using Two Main Types of Chemical Reactions Dehydration (synthesis) reactions: Monomers are linked together to form polymers and a molecule of water is lost Each monomer contributes part of the H2O molecule that is lost

Cells Make and Break Polymers Using Two Main Types of Chemical Reactions Hydrolysis reactions: Polymers are broken down into monomers by the addition of water molecules reverse of the dehydration synthesis reactions

Carbohydrates Functions Contain C, H, and O Polymers of monosaccharides Three classes Monosaccharides -Simple sugars containing three to seven C atoms Ex. Glucose Disaccharides -Double sugars fructose, sucrose, maltose Polysaccharides –many monosaccharides linked together ex., starch, glycogen, cellulose Functions Cellular fuel Provide structure in RNA and DNA

Carbohydrates: Polysaccharides

Lipids Contain C, H, O and sometimes P Mainly insoluble in water Several Classes of Lipids Triglycerides Phospholipids Steroids

Triglycerides Triglycerides—solid fats and liquid oils Three fatty acids bound to glycerol (3:1) Functions Energy storage Insulation Protection

Phospholipids Similar to triglycerides Two fatty acids bound to glycerol (2:1), bound to a phosphate group “Head” and “tail” regions have different properties Main component of cellular membranes

Steroids Composed of four fused carbon rings Ex’s. Cholesterol, vitamin D, steroid hormones, and bile salts

Proteins Contain C, H, O, N, and sometimes S Polymers of amino acids All 20 amino acids have same basic structure Amino acids are held together by peptide bonds (polypeptides)

Denaturing Natural Folding https://www.youtube.com/watch?v=yZ2aY5lxEGE (protein folding animation 2m 19 s) start around 1:11

Nucleic Acids Two examples: DNA and RNA Contain C, O, H, N, and P Polymers of nucleotides: nucleotides have 3 parts: a N-containing base, a pentose sugar, and a phosphate group

Deoxyribonucleic Acid (DNA) Four bases: adenine (A), guanine (G), cytosine (C), and thymine (T) Double-stranded, helical Replicates before cell division, ensuring genetic continuity Provides instructions for protein synthesis

Ribonucleic Acid (RNA) Four bases: adenine (A), guanine (G), cytosine (C), and uracil (U) Uracil replaces thymine in RNA Single-stranded Mainly active outside of nucleus