10. When a radioactive phosphorus is incorporated into DNA strand, the phosphodiester bond generally break after a short while because-

    (1) The bond strength of phosphorus decreases
    (2) Phosphorus on radioactive decay converts into Sulphur, which has valence of two
    (3) It attacks glycosidic bond
    (4) Due to nucleophilic attack of 3’OH group

The Effect of Radioactive Phosphorus on DNA Stability

Understanding Radioactive Phosphorus in DNA

Phosphorus is a key element in the DNA backbone, forming phosphodiester bonds between nucleotides. When radioactive phosphorus (³²P) is incorporated into a DNA strand, it can cause instability and bond breakage due to its radioactive decay.

Why Does the Phosphodiester Bond Break?

Among the given options, the correct answer is:

✔ (2) Phosphorus on radioactive decay converts into Sulphur, which has a valence of two

Mechanism of Phosphodiester Bond Breakage

• ³²P undergoes beta decay, transforming into Sulfur-32 (³²S).
• Sulfur has different chemical properties and bonding capabilities, leading to instability in the DNA backbone.
• This results in the breakage of the phosphodiester bond, affecting DNA integrity.

Biological Implications of Radioactive Phosphorus in DNA

• Used in radiolabeling studies to track DNA synthesis and repair mechanisms.
• Helps in cancer research and treatment, as radioactive phosphorus can target rapidly dividing cells.
• Can cause DNA damage and mutations, leading to cell death or genetic alterations.

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