crossorigin="anonymous">DIFFERENCE BETWEEN THYMINE AND URACIL - Questions House


Difference between thymine and uracil structure

Difference between thymine and uracil structure are as follows:

1. Nitrogenous bases

In DNA, four nitrogen bases are present which are adenine, guanine, cytosine and thymine. In RNA also, four nitrogen bases are present, it has three bases same as DNA which are adenine, guanine, cytosine but it has uracil instead of thymine.

In RNA, uracil binds to adenine by two hydrogen bonds. In DNA, the uracil is replaced by thymine and thus, adenine binds to thymine by two hydrogen bonds.

2. Structural difference

Thymine and uracil both are pyrimidines that has ring structure of four carbon atoms and two nitrogen atoms and they are structurally very similar. Uracil has same structure as thymine, but Uracil is demethylated form of thymine which means methyl group is deleted at the 5′ position.

3. Stability

The methylation of thymine in DNA makes it more stable than RNA and this protects DNA from attack from enzymes. Uracil is energetically less expensive and thus nature used it in RNA.

4. Nature selection

Nature selected uracil in RNA as in RNA quantity is more important than lifespan whereas thymine is used in DNA as to maintain sequence with high fidelity is more crucial.

5. Pairing

The nitrogenous bases always pair up in complementary manner which means purine base pairs with pyrimidine which are held together by weak hydrogen bonds. Uracil, instead of thymine pairs with adenine in RNA. Usually RNA is single-stranded and does not form a double helix as DNA.

Nucleotide and nucleoside

Each nucleotide consists of a sugar which is present in between the phosphate group and a nitrogenous base. Nucleosides contains only sugar and a base.

Difference between thymine and uracil structure

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