1. Wayne M. Becker Lewis J. Kleinsmith Jeff Hardin Gregory Paul Bertoni The World of the Cell Seventh Edition Chapter 2 The Chemistry of the Cell Copyright © 2009 Pearson Education, Inc.. Pages 18-40

2. Five Principles The Importance of: 1. Carbon 2. Water 3. Selectively Permeable Membranes 4. Synthesis by Polymerization of Small Molecules 5. Self-Assembly

3. Nature of Phospholipids -Amphipathic molecules

4. Structure of Phospholipids -Polar Head Groups -Nonpolar tails

5. Lipid Bilayer What defines the specific function of a membrane?

6. Major Intracellular Compartments

7. Membrane Structure -Different Regions -Protein Function -Sugars -Others

8. Protein Channel Types

9. Macromolecules Important Theme: –Small molecular repeat units “condense” to form macromolecules –Macromolecules “self-organize” to mature biological dstructure –Repeat Units - “monomers” –Repeat Units condense: 2 repeat units - “dimer” 3 repeat units - “trimer” Several repeats units - “oligomer” Many repeat units - “polymer”

10. Assembly of Cellular Structures

11. Families of Macromolecules

12. Macromolecule Formation Monomers condense - water is released - Condensation often releases water -“Dehydration condensation” Reverse = “degradation” –Water is added –“Hydrolysis”

13. Simple Sugar Structure Glucose

14. Formation of a Disaccharide Which reaction requires energy?

15. Monomers  Polymers

16. Macromolecules Recurring Theme… Monomers condense to polymers.. Polymers “self-organize” into mature macromolecules..

17. Self Assembly Polymers must assume exact final 3- D shape and structure How “molded” into final 3-D shape? Biological “casting structure”?

18. How do macromolecules assume their final 3-D shape?

19. Casting mold?

20. Anfinsen Expt 1920s Functional Enzyme - –“Pancreatic Ribonuclease” “Denature” (disrupt 3D shape - usually only break non-covalent bonds) Loose biological functionality

21. Denaturation Disrupt 3D structure (mainly through non- covalent bonds) Leave sequence of condensed monomers intact..

22. Anfinsen Expt Remove denaturation agent Molecule spontaneously refolds to original 3D shape! Biological functionality recovered..

23. Anfinsen Expt Means: –No “casting” mold necessary –All information needed to define 3D shape already present in “sequence” of amino acids –“3° structure is defined by 1° structure…” –How……?

24. Defines 3D Structure: “Non-Covelent” Bonds: –H-Bonds –Ionic bonds –VDW Bonds –“Hydrophobic” Bonds

25. “Hydrophobic Interactions” UNFAVORABLE!!

26. “Hydrophobic Interactions”

27. Hydrophobic Interactions Hydrophilic – Water loving -can form hydrogen bonds -dissolve in water Hydrophobic – Water hating -cannot from hydrogen bonds -does not dissolve in water Hydrophobic force is caused by a pushing of nonpolar surfaces out of the hydrogen-bonded water network bringing nonpolar surfaces together

28. Noncovalent Interactions of Macromolecules

29. Final 3-D structure: Final Trade-Off: –Maximize total number of favorable Noncovalent interactions –Minimize total number of unfavorable Noncovalent interactions