The Structure and Function of Macromolecules

1. The Structure and Function of Macromolecules Chapter 5

2. Macromolecules - larger molecules made from smaller ones. • 4 major classes of macromolecules: carbohydrates, lipids, proteins, and nucleic acids. • 3 of these are polymers because they are made from individual building blocks called monomers.

3. Monomers - joined together through condensation or dehydration reaction (form macromolecules) • Requires energy; uses covalent bonds (links together monomers) • Water produced.

4. Water produced as by-product

5. Hydrolysis breaks polymers into monomers. • Water added to polymer; breaks bonds, creates monomers (i.e. digestive process in animals)

7. Carbohydrates • 1Carbohydrates - sugars (monomers) and polymers. • AMonosaccharides - simple sugars. • BDisaccharides - double sugars (monosaccharides linked together) • CPolysaccharides - polymers of monosaccharides. • Sugars named with –ose.

9. Monosaccharides needed for cellular work. • Help to synthesize other macromolecules. • 2 monosaccharides joined by glycosidic linkage to form disaccharide via dehydration.

11. Maltose - 2 glucose molecules. • Sucrose - 1 glucose, 1 fructose.

13. Polysaccharides - energy storage. • Starch - energy storage polysaccharide for plants. • Starch stored in plants plastids. • Herbivores access starch for energy.

15. Animals store energy as glycogen. • Humans - in liver and muscles. • Cellulose – polysaccharide; plant cell walls. • Many herbivores cannot digest cellulose (develop relationships with microbes)

17. Chitin - polysaccharide - makes up exoskeleton of arthropods (like crustaceans). • Chitin - found in fungi; functions as structural support.

18. Chitin is used in surgery

19. Lipids • Lipids - no polymers (exception) • Lipids nonpolar (no affinity for water) • Fat made from glycerol and fatty acids. • Glycerol - 3 carbon molecule with hydroxyl group and fatty acid; consists of carboxyl group attached to long carbon skeleton.

21. The 3 fatty acids in a fat can be same or different. • No carbon-carbon double bonds, molecule is saturated fatty acid (hydrogen at every possible position) • Form bad fats - solid at room temperature (butter, lard)

22. No double-double bonds

23. 1+ carbon-carbon double bonds - molecule is unsaturated fatty acid - formed by removal of hydrogen atoms from carbon skeleton. • Form good fats - liquid at room temperature (oils)

25. Purpose of fat - energy storage. • Gram of fat stores 2X as much energy as gram of polysaccharide. • Fat also cushions vital organs. • Layer of fat can also function as insulation.

26. Phospholipids - 2 fatty acids attached to glycerol, phosphate group at 3rd position. • Fatty acid tails are hydrophobic, phosphate group and attachments form hydrophilic head. • When phospholipids added to water, self-assemble with hydrophobic tails pointing toward center, hydrophilic heads on outside.

29. Phospholipids in cell form bilayer; major component of cell membrane.

30. Hydrophilic Hydrophobic

31. Steroids - lipids with carbon skeleton consisting of 4 fused carbon rings. • Cholesterol - component in animal cell membranes. • Cholesterol – also forms hormones (i.e. testosterone, estrogen)

32. Cholesterol

33. Proteins • Proteins - support, storage, transport, defenses, and enzymes. • Made in ribosomes in cell. • Proteins - amino acids linked together to form polymer. • 20 different amino acids that can be linked together to form thousands of different proteins.

34. Amino acids link - polypeptides - combine to form proteins. • Amino acids made of hydrogen atom, carboxyl group, amino group, variable R group (or side chain). • R group makes amino acids different from one another. • R groups have different properties (i.e. hydrophobic) - form amino acids with different properties.

36. Amino acids joined by peptide bonds when dehydration reaction removes hydroxyl group from carboxyl end of 1 amino acid and hydrogen from amino group of another.

37. Shape of protein determines function. • Shapes - 3 dimensional - determined by sequence of amino acids.

39. Primary structure of protein - linear sequence of amino acids determined by genetics; problem in sequence can cause problem in ending protein created.

42. Secondary structure - hydrogen bonds at regular intervals along polypeptide backbone. • Two shapes are usually formed: alpha coils or beta sheets.

44. Tertiary structure determined by variety of interactions among R groups and between R groups and polypeptide backbone. • Interactions include hydrogen bonds, van der Waals forces, and ionic bonds. • Disulfide bridges help stabilize form.

46. Quarternary structure - joining of 2+ polypeptide subunits. • Collagen and hemoglobin examples.

49. Protein’s shape can change due to environment. • pH, temperature, or salinity (salt concentrations) change - protein can denature (starts to fall apart) • Some proteins can return to functional shape after denaturation, others cannot, especially in crowded environment of cell.