The Molecules of Cells

1. The Molecules of Cells Chapter Three

2. Classes of Compounds • Inorganic 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

3. 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

4. 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

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

6. Carbohydrates • 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

7. Carbohydrates: Polysaccharides

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

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

10. 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

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

12. 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)

13. Denaturing Natural Folding

14. 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

15. 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

16. 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