The Molecules of Cells Chapter Three

Classes of Compounds Inorganic compounds Organic compounds What do they contain? Examples? Organic compounds What do they contain? Examples? Life’s molecular diversity is based on the properties of carbon

Characteristic chemical groups help determine the properties of organic compounds Functional Groups: affect a molecules function by participating in chemical reactions in a characteristic way

Cells make a huge number of large molecules from a small set of small molecules Monomers Polymers There are four classes of Biological macromolecules, three are polymers: Carbohydrates Lipids (not polymers) Proteins Nucleic Acids

Polymers Around Us

Making and Breaking Polymers Dehydration (synthesis) reactions Hydrolysis The reverse of dehydration reactions

Carbohydrates Functions Sugars and starches Contain C, H, and O [(CH20)n] Three classes Monosaccharides- Disaccharides Polysaccharides Functions

(a) Monosaccharides Monomers of carbohydrates Example Hexose sugars Example Pentose sugars Glucose Fructose Galactose Deoxyribose Ribose

(b) Disaccharides Consist of two linked monosaccharides Example Sucrose, maltose, and lactose Glucose Fructose Glucose Glucose Galactose Glucose Sucrose Maltose Lactose

Lipids Contain C, H, O (less than in carbohydrates), and sometimes P Insoluble in water Several Classes of Lipids: Triglycerides Phospholipids Steroids

Triglycerides Triglycerides—solid fats and liquid oils Composition Main functions

Phospholipids Modified triglycerides composed of: “Head” and “tail” regions have different properties Function

Steroids Composition Examples: 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)

Proteins are made from amino acids linked by peptide bonds

Natural Folding Denaturing

Nucleic Acids DNA and RNA Contain C, O, H, N, and P Monomer= nucleotide

Sugar-phosphate backbone Nucleotide Base pair Base pair Figure 3.16C DNA double helix. Sugar-phosphate backbone

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