Question

Which of the followings is true about the DNA ?
(A) DNA contains five carbon sugar.
(B) In DNA Thymine is present in place Uracil.
(C) DNA is central to protein syntheses.
(D) In DNA one of the nucleoside is Uridine.
(E) DNA is usually a double stranded structure.
Choose the correct answer from the options given below :

• A. (A), (B) and (D) only.
• B. (A), (C) and (D) only.
• C. (A), (B) and (E) only.
• D. (B), (C) and (D) only.

Hint:

To differentiate DNA and RNA:
- DNA \(\rightarrow\) Deoxyribose sugar, Thymine (T) base, usually Double-stranded.
- RNA \(\rightarrow\) Ribose sugar, Uracil (U) base, usually Single-stranded.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Deoxyribonucleic acid (DNA) is the primary hereditary material in almost all living organisms, carrying genetic instructions required for growth, development, and reproduction.
Understanding its molecular structure, base composition, and organization is fundamental to molecular biology.

Step 2: Detailed Explanation:
Let us analyze each statement regarding the properties of DNA:
- Statement (A): DNA contains deoxyribose, which is a 5-carbon pentose sugar (five-carbon sugar), making this statement true.
- Statement (B): In DNA, the pyrimidine base Thymine is present, which pairs with Adenine.
Uracil is found in RNA instead of Thymine, making this statement true.
- Statement (C): According to the Central Dogma, DNA is transcribed into messenger RNA (mRNA), which is then translated into proteins on ribosomes.
Therefore, RNA molecules (mRNA, tRNA, rRNA) are directly central to protein synthesis, while DNA acts as the master information template, making this statement conceptually secondary to the structural features in A, B, and E.
- Statement (D): Uridine is a ribonucleoside formed by coupling uracil with a ribose sugar, which is found in RNA, not DNA.
The corresponding nucleosides in DNA are deoxyadenosine, deoxyguanosine, deoxycytidine, and deoxythymidine, making this statement false.
- Statement (E): DNA is usually organized as a double-stranded helical structure (Watson-Crick model), held together by hydrogen bonds between complementary base pairs, making this statement true.
Therefore, statements (A), (B), and (E) are the correct statements about DNA.

Step 3: Final Answer:
The correct statements are (A), (B), and (E) only, corresponding to Option C.