The Molecules of Life

1. The Molecules of Life • Macromolecules • Not all are polymers • Four main classes: • Carbohydrates • Lipids • Proteins • nucleic acids

2. Carbohydrates • Carbohydrates • Monosaccharides (simple sugars) • polysaccharides (macromolecules) • Functions: • cellular fuel • structural components of cell • cell identifiers

3. Monosaccharides • Ratio of molecular formula - CH2O • major fuel and building blocks • Glucose (C6H12O6) • Classified in part by number of carbons

4. 1–4 glycosidic linkage • Disaccharide • two monosaccharides joined by glycosidic linkage • Glucose and fructose are structural isomers Glucose Glucose Maltose (a) Dehydration reaction in the synthesis of maltose 1–2 glycosidic linkage Glucose Fructose Sucrose

5. Polysaccharides • polymers of sugars containing100’s to 1,000’s of monosaccharides • structure and function determined by sugar and positions of glycosidic linkages

6. Storage Polysaccharides Glycogen Starch

7. Structural Polysaccharides • Cellulose • also polymer of glucose, but glycosidic linkages differ • two ring forms for glucose - alpha () and beta ()

8. Structural polysaccharides are difficult to digest How do cows get so fat eating grass???

9. Chitin • found in the exoskeleton of arthropods • provides structural support for fungal cell walls

10. Lipids • Not polymers, hydrophobic, mostly hydrocarbons • Fats • Phospholipids • Steroids • Functions: • structural components of cells • cellular fuel • chemical messengers

11. Fats • Two specific monomers joined by an ester linkage • Glycerol • three-carbon alcohol with a hydroxyl group on each carbon • Fatty acid • carboxyl group attached to long hydrocarbon chain

12. Ester linkage Lipids Fat – simple lipid Fat – Triglyceride

13. Fatty acids vary in length and number and location of double bonds • Saturated • Hydrogenated • Trans fats • Unsaturated • Mono-unsaturated • Poly-unsaturated

14. Phospholipids • Glycerol with 2 fatty acids and a phosphate group • Amphipathic molecule

15. Steroids • Carbon skeleton consists of four fused rings • Functional groups differ • Structural components and hormones

17. Olestra aspartame

18. Proteins • Account for about 50% of the dry mass of cells • Most diverse macromolecule in body • One or more polypeptide polymers • built from the same 20 amino acid monomers linked by peptide bonds

19. Polar amino acids form hydrogen bonds with each other increasing stability of protein Charged amino acids form ionic bonds increasing stability of protein

21. Proteins Amino Acid Polypeptide

24. Sickle-cell disease • Inherited blood disorder • Single amino acid change in hemoglobin protein

25. Denaturation • A protein’s shape is what allows it to function • Denaturation • occurs when proteins encounters harsh environment • changes in temp, pH or salt concentrations Normal protein Denatured protein Renaturation

26. Nucleic acids • Store and transmit hereditary information • There are two types of nucleic acids: • Deoxyribonucleic acid (DNA) • Ribonucleic acid (RNA) • DNA • provides directions for its own replication • directs synthesis of RNA • Through RNA, controls protein synthesis

27. Central Dogma of Molecular Biology • Amino acid sequence of polypeptides coded for by genes • linear sequences of • DNA

28. Nucleic acids are polynucleotides made of nucleotide monomers joined by phosphodiester linkage • Each nucleotide consists of a nitrogenous base, pentose sugar, and phosphate group

29. Directionality based on if 3rd or 5th position carbon is facing outward at end of chain

30. DNA is double stranded • Sugar-phosphate backbone • Nitrogenous bases form hydrogen bonds: • adenine (A) with thymine (T), and guanine (G) with cytosine (C)

31. RNA is single stranded • Thymine base is replaced with uracil • There are three types of RNA: • mRNA, rRNA and tRNA

32. DNA Structure Compared to RNA Structure

33. Nucleotides may have other metabolic functions ATP (Adenosine Triphosphate)