Monomers, polymers, and macromolecules

1. Monomers, polymers, and macromolecules There are 4 categories of macromolecules: Carbohydrates Proteins, Lipids, and Nucleic acids

2. Carbon is the central element • All biomolecules contain a Carbon chain or ring • Carbon has 4 outer shell electrons (valence = 4) • Therefore it’s bonding capacity is great • It forms covalent bonds –hence, has strong bonds • Once bound to other elements (or to other Carbons), it is very stable

3. Carbon linkages CH4 = Propane • Single chains • Rings = C3H8 The 4 types of biomolecules oftenconsist of large carbon chains

4. Carbon binds to more than just hydrogen!! • To OH groups in sugars • To NH2 groups in amino acids • To H2PO4 groups of nucleotides of DNA, RNA, and ATP Amino acid OH, NH2, PO4 are called ‘functional groups’!

5. Fig. 3.1 Functional groups:

6. Isomers have the same molecular formulas but different structures • Structural isomer = difference in the C skeleton structure • Stereoisomer = difference in location of functional groups

7. Enantiomers are special types of stereoisomers Enantiomers are mirror images of each other One such enantiomer contains C bound to 4 different molecules and is called a chiral molecule Chiral molecules rotate polarized light to the right (D form) or to the left (L form) molecules Examples: amino acids (L form) sugars (D form)

8. Monomers and polymers • Monomers are made into polymers via dehydration reactions • Polymers are broken down into monomers via hydrolysis reactions

9. Fig. 3.3

10. Carbohydrates (or sugars) • Simple sugars (monosaccharides) • Only one 3-C, 5-C, 6-C chain or ring involved

11. Fig. 3.5 Examples of sugar monomers* *Remember how C’s are counted within the ring structures (starting from the right side and counting clockwise)

12. Carbohydrates (sugars) • Double sugars (disaccharides) • Two 6-C chains or rings bonded together

13. Carbohydrates (sugars) • Complex carbo’s (polysaccharides) • Starch • Cellulose • Glycogen • Chitin Glycogen to glucose in animals

14. Fig. 3.9 Polysaccharides Starch structure vs Glycogen structure

15. Fig. 3.10 Polysaccharides: Cellulose structure

16. Proteins • Composed of chains of amino acids • 20 amino acids exist • Amino acids contain • Central Carbon • Amine group • Carboxyl group • R group

17. Fig. 3.20 The 20 Amino Acids All differ with respect to their R group

18. Peptide bonds occur between amino acids • The COOH group of 1 amino acid binds to the NH2 group of another amino acid • Forms a peptide bond!

19. Fig. 3.21 The chain (polymer) of amino acids forms a variety of loops, coils, and folded sheets from an assortment of bonds and attractions between amino acids within the chain(s)

20. There are at least 7 functions of proteins • Enzyme catalysts – specific for 1 reaction • Defense – antibody proteins, other proteins • Transport- Hgb, Mgb, transferrins, etc • Support – keratin, fibrin, collagen • Motion – actin/myosin, cytoskeletal fibers • Regulation- some hormones, regulatory proteins on DNA, cell receptors • Storage – Ca and Fe attached to storage proteins

21. Fig. 3.18

22. There are four levels of protein structure • Primary = sequence of aa’s • Secondary = forms pleated sheet, helix, or coil • Tertiary = entire length of aa’s folded into a shape • Quaternary = several aa sequences linked together

23. Fig. 3.23 Motifs and Domains: Important features of 2° and 4° structure

24. Nucleic acids: DNA and RNA • DNA = deoxyribonucleic acid • DNA is a double polymer (chain) • Each chain is made of nucleotides • The 2 chains bond together to form a helix

25. DNA nucleotides • Each nucleotide in DNA contains: • 5-C sugar (deoxyribose) • Phosphate • Nitrogen base -adenine (A) -guanine (G) -cytosine (C) -thymine (T)

26. Fig. 3.14 One polymer of nucleotides on one “backbone” of nucleic acid

27. Fig. 3.15 The DNA “double helix”

28. Lipids: Hydrophobic molecules • Central core of glycerol • Bound to up to 3 fatty acid chains • They exhibit a high number of C-H bonds – therefore much energy and non-polar • When placed in water, lipids spontaneously cluster together • They help organize the interior content of cells  “phospholipids”

29. Glycerol and fatty acid chains What specific bonds form between glycerol and each fatty acid chain? Would you think this to be an hydrolysis or a dehydration synthesis rxn?

30. Saturated and unsaturated fats The difference resides in the number of H’s attached to C’s in the fatty acid chains; the amount of “saturation” on the C’s

31. Saturated vs unsaturated fats and diet • Saturated fats raise LDL-cholesterol levels in the blood (animal fats, dairy, coconut oil, cocoa butter) • Polyunsaturated fats leave LDL-cholesterol unchanged; but lower HDL-cholesterol (safflower and corn oil) • Monounsaturated fats leave LDL and HDL levels unchanged (olive oil, canola, peanut oil, avocados) • One variety of polyunsaturated fat (Omega-3 fatty acids) guards against blood clot formation and reduce fat levels in the blood (certain fish, walnuts, almonds, and tofu)

32. Phospholipids and cell membranes • P-lipids make up the majority of cell membranes including: • The plasma membrane • Nuclear envelope • Endoplasmic reticulum (ER) • Golgi apparatus • Membrane-bound vesicles

33. Structure of single P-lipid The 3 C’s of glycerol are bound to: 2 fatty acid chains phosphate

34. Cell environment organizes P-lipid bilayer to proper orientation Hydrophilic (polar) “heads” of P-lipid oriented to the exterior; hydrophobic (non-polar) “tails” oriented to the interior