Question

Which of the following nitrogen bases is not found in DNA?
A. Thymine
B. Cytosine
C. Guanine
D. Uracil

Answer 1

A nucleotide is an organic molecule with the basic components of a nitrogenous base, pentose sugar, and phosphate. DNA and RNA are polynucleotides made up of a chain of nucleotide monomers with varying nitrogenous bases. Adenosine triphosphate (ATP) is the energy currency of cells (adenosine triphosphate). Nucleotides are necessary for many metabolic activities because they create numerous coenzymes and cofactors such as NAD, NADP, FAD, coenzyme A, and others.
Three covalently linked units make up a nucleotide. They are as follows:
Bases containing nitrogen - Pyrimidine and Purine
Ribose and Deoxyribose are the two sugars that make up pentose sugar.
Monophosphate, diphosphate, and triphosphate are all types of phosphate.

Complete answer:
Option A: Adenine (A), guanine (G), cytosine (C), and thymine (T) are the four nitrogenous bases found in DNA (T).
So, option A is not correct.
Option B: Thymine, cytosine, and uracil are all pyrimidines. The presence of a unique ring structure. Purines are made up of adenine and guanine. As a result, the right response is 'Uracil'.
So, option B is not correct.
Option C: DNA is devoid of uracil. In ribonucleotides, which are components of RNA, uracil is found as a pyrimidine base.
So, option C is not correct.
Option D: DNA is made up of nucleotide monomers. Each nucleotide has a nitrogenous base linked to the deoxyribose sugar via the phosphate moiety.
Adenine (A), guanine (G), cytosine (C), and thymine (T) are the four nitrogenous bases found in DNA (T).
Purine bases - adenine and guanine
pyrimidine bases - cytosine and uracil.
The nitrogenous bases of DNA's double helix are linked by hydrogen bonds.
Guanine and cytosine make a pair, while adenine and thymine make a pair.
So, option D is correct.

Hence, Option D is the correct answer.

Note:
Adenosine, Guanosine, Thymidine, Cytidine, and Uridine are examples of nucleosides.
Nucleotide = Phosphate + Nucleoside
Adenylic acid, Guanylic acid, Thymidylic acid, Cytidylic acid, and Uridylic acid are
examples of nucleotides.
Nucleotides are also known as adenosine monophosphate, adenosine diphosphate, or adenosine triphosphate depending on the amount of phosphate groups connected to them, e.g., adenosine monophosphate, adenosine diphosphate, or adenosine triphosphate.
Nucleotides are the only components of DNA and RNA.