Question

Pyrimidine bases of DNA are:
a. Uracil and Guanine
b. Thymine and Cytosine
c. Adenine and Guanine
d. Adenine and Cytosine

Answer 1

Answer :

b) Thymine and Cytosine.

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Explanation :

Nucleotide are the monomers whose reputation makes polynucleotides or nucleic acid like DNA and RNA.

Nucleotide consists of three components:

1) Nitrogenous base

which is further consists of Purine and Pyrimidine

→ Purine = Adenine, Guanine

→ Pyrimidine = Cytosine, Thymine

2) Pentose sugar

3) Phospheric acid

(All three components together make nucleotide.)

• In structure of DNA, Purine always make H-bond (hydrogen bond) with Pyrimidine. Always Adenine make double bond double bond with Thymine and Cytosine make triple H-bond with Guanine.
• Nucleoside is formed by combination of nitrogeneous base and pentose sugar.

What is Nucleic Acid?

→ These are the chemicals or molecules which are responsible for inheritance of characters. They are present in nucleus of cell.

They are mainly of two types :

1) DNA (Deoxy Ribo Nucleic Acid)

• Thymine is present in it.
• Double stranded structure.

2) RNA (Ribo Nucleic Acid)

• Thymine is replaced by Uracil in it.
• Single-stranded structure.

Answer 2

Pyrimidine bases of DNA are:

a. Uracil and Guanine

b. Thymine and Cytosine ✅✅

c. Adenine and Guanine

d. Adenine and Cytosine

Explanation :---

→ Deoxyribonucleic acid (DNA) is made up of nucleotides consisting of pentose sugar which is β - D - 2 - deoxyribose, Phosphoric acid and bases (Adenine , Guanine , cytosine and thymine)..

→ Pyrimidine is an aromatic heterocyclic organic compound similar to pyridine.

→ Pyrimidine bases in DNA = Cytosine +Thymine..

→ Purine bases in DNA = Adenine+Guanine..

So, Option B is Correct Answer..