Homework SourseWatson and Crick derived their model of DNA structure not fr
Watson and Crick derived their model of DNA structure not from their own laboratory research but rather through the analysis and interpretation of experimental data generated by others, such as Erwin Chargaff, Rosalind Franklin, and Maurice Wilkins. Which of the following provides evidence that DNA nucleotides are arranged as complementary base pairs?
| A. DNA nucleotides contain a five-carbon deoxyribose sugar, a phosphate group, and one of four possible nitrogenous bases. |
| B. The nucleotides forming a single strand of DNA are linked together by covalent phosphodiester bonds. |
| C. Percentages of adenine and thymine are approximately equal to one another, and the percentages of cytosine and guanine are approximately equal to one another. |
| D. Complementary strands of DNA are antiparallel. |
Solution
The correct option is option C. DNA (deoxyribose nucleic acid) is a double helix structure comprising of monomers of nucleotides. There are four different type of nucleotides with one of the four possible nitrogenous base which are adenine, guanine, cytosine and thymine.
As per the Chargaff\'s rule the proportion of nitrogenous bases is not random throughout. The %adenine = % Thymine and %cytosine = % guanine.
Nucleotides containing adenine would only interact with that containing thymine, while that of cytosine would only interact with guanine which means only two kinds of base pairs are possible either GC or AT. Hence the two strands complement each other which is known as complement base pairings.
