1. LEHNINGER PRINCIPLES OF BIOCHEMISTRY
David L. Nelson and Michael M. Cox
LEHNINGER
PRINCIPLES OF BIOCHEMISTRY
Sixth Edition
CHAPTER 1
The Foundations of Biochemistry
© 2013 W. H. Freeman and Company

2. Pancreatic cell section

3. Universal features of living cells

4. Phylogeny of the three domains of life

5. Classification of Organisms

10. Several functional groups in a single biomolecule

12. Complementary fit between a macromolecule and a small molecule

13. Stereoisomers have different effects in humans

14. Many drugs are racemic mixtures

15. Energy Transformations in Living Organisms

16. The major carrier of chemical energy in all cells is adenosine triphosphate (ATP)

17. LEHNINGER PRINCIPLES OF BIOCHEMISTRY
David L. Nelson and Michael M. Cox
LEHNINGER
PRINCIPLES OF BIOCHEMISTRY
Sixth Edition
CHAPTER 2
Water
© 2013 W. H. Freeman and Company

18. Water

19. Hydrogen bonding in ice

20. Common hydrogen bonds in biological systems

21. Biologically important hydrogen bonds

22. Directionality of the hydrogen bond

24. Water as a solvent

26. Amphipathic compounds in aqueous solution

27. Dispersion of lipids in water

28. Release of ordered water is energetically favorable

31. Ionization of water

33. Conjugate acid-base pairs consist of a proton donor and a proton acceptor

34. Titration curve of acetic acid

36. H2O H2O OH- + H+ [OH-] [H+] Keq = [H2O] Kw = [OH-] [H+] = 10-14 M2
Pure H2O : [H+] = [OH-] = 10-7 M
pH = - log [H+] = -log (10-7) = 7
If [H+] > 10-7 M then pH < 7 (acidic)
If [H+] < 10-7 M then pH > 7 (basic)
Blood: [H+] = 4 x 10-8 M
Blood pH = 7.4
Equilibrium
constant =
= 1.8 x M
Ion product
of water =

37. Acids and Bases O O P OH OH
Acid (HA) - something that has a proton and is willing to give it up.
Base (A-) - something that has a place to put a proton
HA H+ + A HA + H2O H3O+ + A-
Strong acids completely dissolve in H2O (H+Cl-).
Weak acids don’t completely dissolve in H2O.
[A-] [H+]
K =
[HA]
H2PO HPO42- + H+
(acid) (base)
[HPO42-] [H+]
Ka = = 1.51 x 10-7 M
[H2PO4-]
pKa = - log (Ka) = 6.82 O
O P OH OH

38. Relationship between pH and pKa
Henderson – Hasselbalch equation
pH = pKa when:
The molar concentration of acid and conjugate base are equal
[H2PO4-] = [HPO42-]
pH = pKa = 6.8

39. Physiological pH
The pH in the human body needs to remain ~7. Enzyme catalysis, protein-protein interactions, receptor binding, and other biological processes are very sensitive to pH.
pH balance of the blood is maintained using a CO2 - bicarbonate buffer.
CO2 + H2O H2CO H+ + HCO3- pKa = 6.1
(acid) (hydrated (bicarbonate
CO2) base)
There is more than 10-fold more base (HCO3-) than acid (CO2) so pH > pK (pH= 7.4)
CO2 is exhaled by the lungs H+ + HCO CO2 + H2O
Breathing rate controls CO2
CO2 balance is controlled by the lungs, HCO3- by the kidneys