1. The Nature of Molecules
Chapter 2

2. Properties of Water
Water is a key inorganic molecule, involved in biological processes for several reasons:
1. Water is a good solvent.
- Water dissolves polar molecules and ions.

3. Properties of Water

4. Properties of Water 2. Water organizes nonpolar molecules.
- hydrophilic: “water-loving”
-hydrophobic: “water-fearing”
- Water causes hydrophobic molecules to aggregate or assume specific shapes.
3. Water can form ions.
H2O  OH H+1
hydroxide ion hydrogen ion

6. Lipids

7. The Chemical Building Blocks of Life
Chapter 3

8. Biological Molecules Biological molecules consist primarily of
-carbon bonded to carbon, or
-carbon bonded to other molecules.
Carbon can form up to 4 covalent bonds.

9. Isomers: molecules with same chem. formula.
but a different arrangement(Shape)
Biological molecules are typically large molecules constructed from smaller subunits.
Monomer: single subunit
Polymer: many units

10. dehydration synthesis: formation of large molecules by the removal of water
-monomers  polymers
hydrolysis: breakdown of large molecules by the addition of water
-polymers  monomers

11. Biological Molecules

12. Carbohydrates Molecules with a 1:2:1 ratio of C, H, O
-empirical formula: (CH2O)n
-examples: sugars, starch, glucose
C – H covalent bonds hold much energy
Carbohydrates are good energy storage molecules.

13. Carbohydrates Glucose -a monosaccharide – single sugar
-contains 6 carbons
-very important in energy storage
-fructose & galactose are isomers

14. Carbohydrates

15. Carbohydrates Disaccharides
-2 monosaccharides linked together by dehydration synthesis
-used for sugar transport or energy storage
-examples: sucrose, lactose, maltose

16. Carbohydrates

17. Carbohydrates Polysaccharides -long chains of sugars
-used for energy storage
(plants use starch; animals use glycogen)
-used for structural support
(plants use cellulose; animals use chitin)

18. Carbohydrates - starch

19. Carbohydrates - glycogen

20. Carbohydrates - cellulose

21. Carbohydrates - chitin

22. Nucleic Acids Two types: DNA and RNA
Functions: specialized for the storage, transmission, and use of genetic information

23. Nucleic acids are polymers of nucleotides.
-nucleotide: (Monomer)
sugar + phosphate + nitrogenous base
DNA
molecule
Nucleotide

24. -Nitrogenous bases include
-purines: adenine and guanine
-pyrimidines: thymine, cytosine, uracil
A pairs with T (or U in RNA)
C pairs with G
Order of the bases determines genetics

25. Nucleotide

26. Segment of DNA

27. DNA

28. Nucleic Acids RNA -contains ribose instead of deoxyribose
-contains uracil instead of thymine
-single polynucleotide strand
-functions:
-read the genetic information in DNA
-direct the synthesis of proteins

29. Nucleic Acids

30. Proteins Protein functions include: 1. enzyme catalysts 2. defense
3. transport
4. support
5. motion
6. regulation
7. storage

31. Proteins Monomer: Amino acid -central carbon atom surrounded by
-amino group
-carboxyl group
-single hydrogen
-variable R group (dictates the chemical properties of the amino acid)

32. Proteins

33. Proteins The structure of a protein determines its function
1) order of amino acids
2) folding and final shape

34. Proteins
Denaturation is a change in the shape of a protein, usually causing loss of function.
-can be caused by changes in:
-pH
-temperature
-salt concentration

35. Proteins

36. Lipids
Lipids are a group of molecules that are insoluble in water (hydrophobic)
Two main categories:
-fats (triglycerides)
-phospholipids
Monomers: Fatty acids hydrocarbon chains containing a carboxyl group (COOH)

37. Lipids
Triglycerides (fats)
-composed of 1 glycerol + 3 fatty acids

38. Lipids Triglycerides -composed of 1 glycerol + 3 fatty acids
-store twice as much energy as carbohydrates
-saturated fats (animals) solid at room T
-unsaturated fats (plant oils) liquid at room T

39. Lipids – saturated (each C bonded to 4 other atoms)

40. Lipids – unsaturated (double bonds on some C)

41. Lipids Phospholipids -composed of: -1 glycerol -2 fatty acids
-a phosphate group
Phospholipids contain polar “heads” and nonpolar “tails”.

42. Lipids
Phospholipids spontaneously form micelles or lipid bilayers  cell membranes!
hydrophobic regions toward the inside and leave the hydrophilic regions exposed to the water environment.

43. Lipids

44. Lipids

45. Lipids