Chargaffs and his rules

Question 1

Erwin Chargaff was interested in what and what four bases?

Answer 1

Interested in base composition of DNA
Quantified relative amounts of 
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)

Question 2

What are the purines and pyrimidines?

Answer 2

purines are Adenine and Guanine

pyrimidines are cytosine and thymine

Question 3

What are the four Chargaff’s rules?

Answer 3

1. DNA from different cells have same percentage of each four bases
2. Percentage does not vary
3. DNA does vary from species to species
4. A=T, G=C, A+G=C+T

Question 4

percentages do not vary:

Answer 4

within an individual
tissue age
Nutritional State
Environment

Question 5

How does DNA vary from species to species?

Answer 5

Closely related species have similar compositions

Different species exhibit different base composition