MICROANATOMY

Detailed explanation-1: -The fact that uracil is present in RNA and not DNA contributes to the ability of RNA to be degraded easily. This allows the cell to change which genes are being expressed, as the older RNAs do not stick around for very long.

Detailed explanation-2: -A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base. The bases used in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T). In RNA, the base uracil (U) takes the place of thymine.

Detailed explanation-3: -RNA is single stranded but DNA is double stranded. DNA polynucleotide contains thymine but RNA polynucleotide contains uracil.

Detailed explanation-4: -Thymine is easily oxidized. So it is protected from oxygen in the nucleus. Outside of the nucleus, it is quickly destroyed. Uracil is resistant to oxidation and is utilized in RNA, which exists outside of the nucleus.