Question

Which of the following is not present in DNA?
A. Adenine
B. Guanine
C. Thymine
D. Uracil

Answer 1

DNA, or deoxyribonucleic acid, is the genetic material found inside every living creature. In DNA, four different bases are present, two are the larger purines (Adenine and Thymine) and other two (Guanine and cytosine) the smaller pyrimidines.

Complete step by step answer:
The deoxyribonucleic acid controls a lot of visible and invisible characteristics in an individual’s chromosomes. Race, colouring and sex are the visible characteristics and the blood groups and chances of developing inherited diseases comes under invisible characteristics. DNA is made up of molecules called nucleotides. All nucleotides contain a sugar group, a phosphate group, and a nitrogen base. Nitrogen bases are of four types. They are adenine (A), thymine (T), guanine (G) and cytosine (C). Adenine and thymine are paired by two H bonds, a double bond, whereas cytosine and guanine are paired by three H bonds, a triple bond. The Deoxyribonucleic acid is the same component in all the cells. DNA contains a double helical structure. Here, the outer edges are formed by alternating deoxyribose sugar and phosphate groups, this is the sugar-phosphate backbone. The two strands are in the opposite directions, ie, the nucleotides in each strand of DNA are complementary to each other.
Hence, DNA contains Adenine, Guanine, Thymine and Cytosine whereas uracil is present in RNA.

Hence, the answer is option D.

Note: Nucleobases are nitrogen-containing biological compounds that form nucleosides, they are also known as nitrogenous bases. They are the components of nucleotides.
RNA is ribonucleic acid, RNA also contains four different bases. The three bases, adenine, guanine, and cytosine are the same as in DNA. But RNA contains uracil instead of thymine.