Understanding the Sugar Difference in DNA and RNA
This question asks us to identify the specific difference between the sugar components of DNA (Deoxyribonucleic acid) and RNA (Ribonucleic acid). Both DNA and RNA are nucleic acids essential for storing and transmitting genetic information, and their structure relies on sugar molecules.
The Core Chemical Distinction: Ribose vs. Deoxyribose
The fundamental difference between the sugars in DNA and RNA lies in their chemical structure, specifically concerning the sugar type and an oxygen atom.
- DNA contains a sugar called 2'-deoxy-D-ribose.
- RNA contains a sugar called D-ribose.
Structural Difference Explained
The key difference is found at the 2' (two-prime) carbon atom of the sugar ring. Both sugars are five-carbon sugars (pentoses).
- In D-ribose (RNA), the 2' carbon atom has a hydroxyl group ($-OH$) attached.
- In 2'-deoxy-D-ribose (DNA), the 2' carbon atom has only a hydrogen atom ($-H$) attached. The term 'deoxy' indicates the absence of this oxygen atom.
This structural variation affects the stability and properties of the nucleic acids. DNA, with its deoxyribose sugar, is generally more stable than RNA, which is important for its role as the long-term genetic blueprint.
Comparison Table: DNA Sugar vs. RNA Sugar
| Characteristic | Sugar in DNA | Sugar in RNA |
|---|---|---|
| Sugar Name | 2'-deoxy-D-ribose | D-ribose |
| 2' Carbon Group | Hydrogen atom ($-H$) | Hydroxyl group ($-OH$) |
| Oxygen Atom at 2' Position | Absent | Present |
Evaluating Other Options
Let's examine why the other options are incorrect:
- Option 1: Neuraminic acid is not the sugar component of DNA or RNA. This option is chemically inaccurate.
- Option 2: Adenine is a nitrogenous base, a crucial part of DNA and RNA nucleotides, but it is not the sugar backbone. This option confuses bases with sugars.
- Option 3: While ribose is a reducing sugar, this statement isn't the most precise or defining difference. Both ribose and deoxyribose exhibit reducing properties under certain conditions. The key difference is the presence or absence of the hydroxyl group at the 2' carbon.
Conclusion
The correct identification of the difference is that DNA utilizes 2'-deoxy-D-ribose, while RNA utilizes D-ribose, with the distinction being the presence of a hydroxyl group at the 2' position in ribose and its absence in deoxyribose.
Important Questions from Miscellaneous
- Which of the following relationships is/are not true?
(A). Most probable velocity = $\sqrt{\frac{2RT}{M}}$
(B). PV = $\frac{3}{2}kT$
(C). Compressibility factor Z = $\frac{pV}{nRT}$
(D). Average kinetic energy of gas = $\frac{1}{2}kT$
Choose the correct answer from the options given below - Match List-I with List-II
List-I List-II Electronic Configuration First Ionisation energy (kJ mol$^{-1}$) (A). ns$^2$ (I). 2100 (B). ns$^2$np$^1$ (II). 1400 (C). ns$^2$np$^3$ (III). 800 (D). ns$^2$np$^6$ (IV). 900
Choose the correct answer from the options given below: - The shielding constant of a 2p electron (calculated using Slater's rules) is
- Match List-I with List-II
List-I List-II Spectroscopy Property (A). Raman (I). Polarizability (B). FTIR (II). Dipole Moment (C). UV-Visible (III). Absorbance (D). NMR (IV). Spin
Choose the correct answer from the options given below: - The structure of protein comprises of:
(A). Primary structure of protein is associated with amino acids
(B). Secondary structure of protein is associated to peptides
(C). Tertiary structure of protein is associated with polypeptide chains
(D). Quaternary structure of protein is associated with polypeptide chains
Choose the correct answer from the options given below:
