Chapter 5 The Structure And Function Of Macromolecules

1. Chapter 5The Structure And Function Of Macromolecules

2. Dehydration Synthesis vs. Hydrolysis Remove water to link monomers Add water to break unlink monomers

3. Monosaccharides - The Simplest Sugars

4. Isomers C6H12O6 Galactose Glucose

5. Numbering The Carbons • Carbon atoms are numbered. Carbon-1 contains the aldehyde functional group. • This is a hexose sugar. It contains 6 carbon atoms. • This is a linear form of a sugar molecule.

6. Numbering The Carbons • Carbons are numbered clockwise beginning with #1, just to the right of the oxygen atom in the ring structure. • The ring forms are known as pyranose forms because they resemble a molecule called a pyran.

7. Linear vs. Ring Forms The predominant forms of glucose and fructose in solution are ring forms. The aldehyde group on carbon-1 reacts with the alcohol group on carbon-5

8. Linear and Ring Forms α-D-Glucopyranose If the –OH group on carbon #1 is down (below the plane of the molecule, it’s the α form. If it’s up, it’s the β form. Living things tend to like the alpha form best.

9. Common Dissacharides Sucrose (Table Sugar = Glucose + Fructose Lactose (Milk Sugar) = Glucose + Galactose Maltose (Malt Sugar) = Glucose + Glucose All three have the chemical formula C12H22O11

10. Alpha - Glycosidic Linkages

11. Linkages in Polysaccharides α1-4 β1-4

12. Properties of Polysaccharides • Composed of many simple sugar monomers • May be branched or unbranched • May be food storage or structural parts • Monomers may be glucose or modified glucose • Linkages may be alpha or beta forms

13. Polysaccharides Alpha 1-4 or Alpha 1-6 if branched

14. Cellulose:β-1-4 Linked Polymer of Glucose

15. Chitin – A Substituted Sugar Chitin The difference between cellulose molecules and chitin molecules is that chitin has an amide group instead of a hydroxyl group (alcohol), which cellulose has.

16. Chitosan Chitosan is a polymer derived from chitin and is used in applications from health care to agriculture to dyes for fabrics. There are even medical applications and companies who use products made with chitosan as part of weight loss programs.Chitosan is very similar to chitin, see below. The difference is that chitosan has an amine group instead of an amide group. This just means that chitosan doesn't have any carbons double bonded to oxygen and chitin does. Chitosan

17. Lipids • Lipids are used for energy storage • Lipids are generally hydrophobic • Can be joined to proteins to make lipoproteins • Can be joined to sugars to make glycolipids • May be used for insulation or protection • Major component of cell membranes

18. Triglycerides • Fats and oils for energy storage • 3 Fatty acids + 1 glycerol molecule joined by an ester bond • 9 cal/gram • The 3 fatty acids may be different • Fatty acids vary from approx. 12-18 Carbons in length • Unsaturated fatty acids contain one or more C=C bonds

20. Saturated vs. Unsaturated

21. Phospholipid Structure

22. Phospholipid Behavior

23. Steroids

24. Proteins Structural Proteins – Support Storage Proteins – Store amino acids Transport Proteins – Move materials Hormonal Proteins – Insulin, glucagon Receptor Proteins – Cell membranes Contractile Protein – Actin and Myosin Defense Protein – Antibodies Enzymatic Proteins – Increase reaction rate

25. Amino Acid Structure H O H – N – C – C – OH H R R - groups are functional groups that may be nonpolar hydrocarbons, polar, or charged. Functional groups give proteins their unique structures and functions.

26. Nonpolar R – Groups

27. Polar and Charged R – Groups

28. Formation of the Peptide Bond

29. Amino Acids • There are 8 essential amino acids for adults. A 9th one (Histidine) is essential to infants. • Since there are 20 amino acids, a chain of 100 amino acids would have 20100 possible combinations of amino acid sequences. That’s a lot!!!

30. Four Levels Of Protein Structure • Primary structure: The order of the amino acids in the protein chain. • Secondary Structure:Alpha helix and Beta pleated sheets, resulting from hydrogen bonding patterns. • Tertiary Structure: Folding of the entire protein due to many interactions. • Quaternary Structure: Several proteins associate to form one large structure.

31. Primary Structure Peptide bonds

32. Secondary Structure Beta pleated sheet Alpha helix

33. Tertiary Structure

34. Quaternary Structure

35. In sickle cell anemia, glutamic acid at position 6 of the beta chains is replaced by the nonpolar amino acid, valine. Oxygen affinity is unaffected, but placing the nonpolar valine on the outside of the molecule markedly reduces the solubility of the deoxygenated form of hemoglobin. The result is sickling when O2 concentrations are low.

36. Amino Acid Sequence Matters

37. Quaternary Structure of the Enzyme, Ribonuclease

38. X-Ray Crystallography

39. Summary of the 4 Levels of Structure

40. Protein Denaturation Heat, Acids, Bases, And Salts Can Cause Proteins To Denature (Change their folding pattern).

41. Nucleic Acids

42. The Central Dogma Of Biology

43. Properties of Nucleic Acids(DNA and RNA) • Polymers consisting of monomers called nucleotides • Nucleotides are composed of 3 parts: Sugar, phosphate and one of 4 bases • Bases may be adenine, guanine, cytosine, thymine (DNA only), and uracil (RNA only) • Sugars: Deoxyribose (DNA only); Ribose (RNA only) • Purine bases are (adenine and guanine), pyrimidines are (cytosine, thymine, and uracil) • Negatively charged at physiological pH

45. DNA • Double helical structure • Sugar-phosphate backbone on the outside • Bases on the inside – hydrogen bonded together • A purine always pairs with its complementary pyrimidine: A-T, G-C • Contains genetic information as a unique sequence of bases

46. Replication of DNA

47. DNA and Evolution • Genes (DNA) and proteins document the heredity of an organism • Related species have similar DNA and protein sequences • Mutation rates may serve as molecular clocks if we know how often they occur