BIOMOLECULES AND ENZYMES

Detailed explanation-1: -However, unlike DNA, RNA is usually a single-stranded molecule. Also, the sugar in RNA is ribose instead of deoxyribose (ribose contains one more hydroxyl group on the second carbon), which accounts for the molecule’s name. RNA consists of four nitrogenous bases : adenine, cytosine, uracil, and guanine.

Detailed explanation-2: -The chemical structure of RNA is very similar to that of DNA, but differs in three primary ways: Unlike double-stranded DNA, RNA is usually a single-stranded molecule (ssRNA) in many of its biological roles and consists of much shorter chains of nucleotides.

Detailed explanation-3: -Whereas DNA always occurs in cells as a double-stranded helix, RNA is single-stranded. RNA chains therefore fold up into a variety of shapes, just as a polypeptide chain folds up to form the final shape of a protein (Figure 6-6).

Detailed explanation-4: -There are two reasons why RNA is generally single-stranded: RNAses are extremely abundant in most cells. Usually, double-stranded RNA is associated with a viral infection and is destroyed rapidly. Double-stranded RNA is not as stable as double-stranded DNA.

Detailed explanation-5: -The nitrogenous bases include adenine, guanine, uracil, and cytosine. RNA mostly exists in the single-stranded form, but there are special RNA viruses that are double-stranded.