1. CHAPTER 2 The Nature of Molecules

2. Which Elements Are Most Significant To Biologists? Six of these plus a few other trace elements

3. Figure 2.3 Nitrogen deficiency All plants need nitrogen to grow. Do you know why?

4. Heavy isotopes are used As biological Tracers Do you know Why? ISOTOPES 3 H hydrogen (tritium) 14 C carbon 32 P phosphorous 35 S sulfur 131 Iiodine

5. Figure 2.8 The Tokaimura nuclear accident

6. RADIOACTIVE TRACERS Examples of how biologists use isotopes to trace specific molecules AUTORADIOGRAPHY - locate specific molecules within cells w/ X-ray film SCINTILLATION COUNTER - follow and chart metabolic activity within cells PET SCAN - Positron Emission Tomography reveals location of intense chemical activity

7. Figure 2.6 Using radioactive isotopes to study cell chemistry

8. Figure 2.4 Goiter Iodine is used to trace thyroid problems

9. Figure 2.5 Two simplified models of a helium (He) atom

10. Figure 2.9 Energy levels of an atom’s electrons

11. Figure 2.11 Electron orbitals

12. Figure 2.10 Electron configurations of the first 18 elements

13. IONIC BONDS the transfer of electrons loss of electron(s) cation gain of electron(s) anion dissociate in aq. soln.

14. Figure 2.15 A sodium chloride crystal

15. COVALENT BONDS sharing of electron pairs strong bonds in aqueous solution The most common bond in organic molecules

16. COVALENT BONDS sharing of electron pairs strong bonds in aqueous solution NONPOLAR COVALENT BOND CH 4 C & H equal affinity for electrons

17. Figure 2.12x Methane What is the shape of this molecule? Why does this molecule have this shape?

18. COVALENT BONDS POLAR COVALENT BOND H2OH2O ELECTRONEGATIVITY each atom in polar bond has partial charge creating opposite poles or polarity remember O and N bonded to H

19. Figure 2.13 Polar covalent bonds in a water molecule

20. HYDROGEN BONDS weak bonds bonds between polar molecules or polar parts of large macromolecules. H-bonds give macromolecules their 3-D shape. hydration shells water forms hydration shells around ions

21. HYDROGEN BONDS You must understand hydrogen interactions to understand biochemistry

22. Hydrophobic Interactions nonpolar w/ nonpolar squeeze out water Important in shaping and organizing the molecules of life

23. Most Common Bond in Life Covalent Bond Electrons are shared Overlapping orbitals & lack of charge strong in aqueous solution

24. Covalent bonds are not all created equal Nonpolar Covalent atoms share electrons equally Example: O 2 CH 4 Polar Covalent Atoms shared electrons unequally Slightly positive and slightly negative pole H 2 O NH 3 Hate hanging out w/ water Love hanging out w/ water Why?????

25. Hydrogen Bonds

26. Hydrogen Bond Technically these are Fake Bonds Interactions between polar molecules molecules with slightly charged poles can hydrogen bond sticky

27. Hydrogen bonds give water many special properties sticky Effects on Temperature Great solvent Also very important Determines 3D shape of many organic molecules!!!!!

28. The Medium of Life hydrophobic Vs. hydrophilic Biochemistry is wet chemistry Only molecule found in all three states on the surface of the earth

29. Hydrogen bonds give water many special properties sticky

30. Hydrogen bonds help determine the shape of macromolecules

31. Review of some helpful terms Atoms Molecules Macromolecules ProtonsFunctional GroupsCarb’s NeutronsNonpolarLipids ElectronsPolarProteins Nucleic Acids IonsInorganic IsotopesOrganic How are these used? How do these How do these differ? differ?

32. An the most important Love/Hate Relationship on earth Hydrophobic Hydrophilic

33. 3-D shape is essential to structure/function

34. Unnumbered Figure (Page 38) Chemical reaction between hydrogen and oxygen

35. Figure 2.20 Photosynthesis: a solar-powered rearrangement of matter The bubbles are evidence that ???? Is taking place Can you fill in the ?????