MDCAT 2026 MCQs

Hydrogen bonds join bases across the two DNA strands.
Covalent phosphodiester bonds form each strand's backbone.

DNA is a polymer made of nucleotides.
Each nucleotide contains a sugar, phosphate, and nitrogenous base.

Hydrogen bonds join bases across the two DNA strands.
Covalent phosphodiester bonds form each strand's backbone.

DNA is a polymer made of nucleotides.
Each nucleotide contains a sugar, phosphate, and nitrogenous base.

Phosphodiester bonds connect the sugar of one nucleotide to the phosphate of the next.
They form the sugar-phosphate backbone.

DNA contains the five-carbon sugar deoxyribose.
RNA contains ribose instead.

Phosphodiester bonds connect the sugar of one nucleotide to the phosphate of the next.
They form the sugar-phosphate backbone.

DNA contains the five-carbon sugar deoxyribose.
RNA contains ribose instead.

Phosphodiester bonds connect the sugar of one nucleotide to the phosphate of the next.
They form the sugar-phosphate backbone.

DNA contains the five-carbon sugar deoxyribose.
RNA contains ribose instead.

One strand runs 5′ to 3′ and the other 3′ to 5′.
This orientation is important for replication enzymes.

Purines have a double-ring structure.
Adenine and guanine occur in both DNA and RNA.