1. What are Chargaff’s rules?
● Studied DNA from many different species
● Interested in the four different nitrogen bases of DNA: adenine (A), guanine (G), cytosine (C), and thymine (T)
● Discovered concentrations of the four bases differed from one species to another
● Observed within each species -- concentration of adenine (about the same) concentration of thymine.
-- concentrations of guanine and cytosine (about the same)
2. Identify the structure of the DNA molecule. What are nucleotides?
●A Nucleic Acid macromolecule (Textbook page 171)
● Double helix shape of two polynucleotide chains of DNA
● Made from nucleotide monomers with 3 parts:
3. What makes up a nucleotide?
● phosphate group
● sugar “deoxyribose”
● nitrogen-containing base (A,C, G, or T) (Held together with H-bonding)
Adenine & Guanine 2-ring; Thymine & Cytosine 1-ring
(Knowing structure helps in better understanding function)
4. Why is DNA replication said to be semi-conservative?
The two daughter molecules contain one strand from the parent molecule and one new strand that is complementary to it…
ie, half of the parent DNA molecule is conserved in each of the two daughter DNA molecules.
