¨       What is the role of DNA?

a.         to control the production of proteins within the cell

b.         form the structural units of cells

c.         control all chemical processes within the cell

¨       What are the two functions of DNA?

1.         to store and use information to direct the activities of the cell

2.         to copy itself exactly for new cells that are created

¨       Both DNA and RNA are nucleotides, which are repeating subunits and monomers.

¨       DNA molecules consist of 3 parts:

1.         a five-carbon sugar (deoxyribose)

2.         a phosphate group

3.         a nitrogen base

¨       1. and 2. are the same in every nucleotide but the nitrogen base changes.

¨       There are four nitrogen bases:

adenine                                     thymine

            Purines                                     Pyrimidines

guanine                                     cytosine

¨       Purines have a double carbon ring and pyrimidines have a single carbon ring.

¨       Each nucleotide bonds with other ones to form a long strand

¨       Two of these strands bond together to form a molecule of DNA which twist to form a double helix.

¨       Watson and Crick made this discovery in 1953.

¨       The DNA resemble a twisted ladder with the sides of the ladder being alternating sugar and phosphate groups and the rungs are bonded nitrogen bases.

¨       An actual DNA molecule has a right handed twist with each full turn consisting of 10 base pairs.

¨       The two strands are held together by hydrogen bonds which form between the purines and pyrimidines.

adenine-thymine                        cytosine-guanine