1. How many types of nucleotides are in DNA, and how do they differ?

2. How are the base pairing rules
related to Chargaff’s research on DNA?

3 .Explain how the double helix model of DNA built on the research of Rosalind Franklin.

4. Which part of a DNA molecule carries the genetic instructions that are unique for each individual: the sugar-phosphate backbone or the nitrogen-containing bases? Explain.

5. In a sample of yeast DNA, 31.5% of the bases are adenine (A). Predict the approximate percentages of C, G, and T. Explain.

6.The DNA of all organisms contains the same four bases(adenine, thymine, cytosine, and guanine). What might this similarity indicate about the origins of life on Earth?