Structure Of Dna And Rna

To determine the complementary strand of the given DNA sequence, we need to understand the base pairing rules of DNA. In DNA, the bases pair as follows: Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).

The given DNA sequence is 5’ – GTATTACG – 3’. We will find the complementary strand by pairing each base with its complement:

• G pairs with C
• T pairs with A
• A pairs with T
• T pairs with A
• T pairs with A
• A pairs with T
• C pairs with G
• G pairs with C

Therefore, the sequence of the complementary strand, starting from the 3' end, is:

3’ – CATAATGC – 5’

Thus, the correct answer is 3’ – CATAATGC – 5’.

To solve the problem of matching scientists with their corresponding contributions from List-I and List-II, follow these steps:

This matching is based on their significant scientific contributions:

• A. Jeffreys: Known for developing techniques for DNA fingerprinting, revolutionizing forensic science.
• Miescher: Discovered nuclein, which we now know as DNA, from white blood cells.
• J. Monod: Famous for work on the transcriptionally regulated system, especially in bacterial cells.
• S.L. Miller: Conducted experiments on amino acid formation under prebiotic conditions, supporting the origin of life studies.

The correct set of matches is: (A)-(III), (B)-(I), (C)-(IV), (D)-(II).

• A phosphate group
• A sugar molecule (deoxyribose)
• A nitrogenous base

• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T)

• Adenine
• Guanine
• Cytosine
• Thiamine

RNA is considered labile, or chemically unstable, largely due to the presence of the 2’-OH (hydroxyl) group in its ribose sugar. This hydroxyl group is located on the second carbon of the ribose ring, which is a crucial structural difference from DNA, where the second carbon is bonded to a hydrogen atom instead.

The presence of this 2’-OH group makes RNA more susceptible to hydrolysis. Here's a breakdown of how this occurs:

1. Structure of RNA: RNA consists of a long chain of nucleotides, each comprising a ribose sugar, a phosphate group, and a nitrogenous base.
2. Role of the 2’-OH Group: The 2’-OH group in RNA can form a nucleophilic attack on the adjacent phosphorus atom in the phosphate backbone, which can lead to strand scission.
3. Mechanism of Hydrolysis: In physiological conditions, the 2’-OH can interact with water or other catalysts, leading to the cleavage of the phosphodiester bond. This susceptibility to hydrolysis makes the RNA molecule more unstable compared to DNA.

In conclusion, the presence of the 2’-OH group in the ribose sugar of RNA makes it a more labile molecule, thus differentiating it from DNA, which lacks this hydroxyl group.