NEET BIOLOGY

Detailed explanation-1: -Further a 1:1 stoichiometric ratio of purine and pyrimidine bases (i.e., A+G=T+C ) should exist. This pattern is found in both strands of the DNA. They were discovered by Austrian-born chemist Erwin Chargaff, in the late 1940s.

Detailed explanation-2: -This sentence refers to the work of Erwin Chargaff, a biochemist at Columbia University. In the late 1940s, Chargaff analyzed the proportions of the four different types of base molecules in DNA, and found that DNA always contains equal amounts of guanine and cytosine, and equal amounts of adenine and thymine.

Detailed explanation-3: -Erwin Chargaff found that in DNA, the ratios of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are equal. This parity is obvious in the final DNA structure.

Detailed explanation-4: -Key conclusions from Erwin Chargaff’s work are now known as Chargaff’s rules. The first and best known achievement was to show that in natural DNA the number of guanine units equals the number of cytosine units and the number of adenine units equals the number of thymine units.

Detailed explanation-5: -Chargaff adapted the paper chromatography technique to separate out the four nitrogenous bases of DNA. The four bases of DNA-adenine, guanine, thymine and cytosine-are the parts of the molecule that do the actual coding of our genes.