Difference between pyrimidine and purine
Pyrimidines and purines are two different types of nitrogenous bases that are found in the DNA and RNA of living organisms.
Pyrimidines are a class of nitrogenous bases that are made up of a single ring structure. The three main pyrimidines found in DNA and RNA are cytosine (C), thymine (T), and uracil (U). Cytosine is found in both DNA and RNA, while thymine is found only in DNA and uracil is found only in RNA.
Purines, on the other hand, are a class of nitrogenous bases that are made up of a double ring structure. The two main purines found in DNA and RNA are adenine (A) and guanine (G). Adenine and guanine are both found in both DNA and RNA.
The main difference between pyrimidines and purines is the number of rings in their structure. Pyrimidines have only one ring while purines have two rings. This difference affects how these bases pair with each other during the process of DNA replication and transcription. Specifically, purines always pair with pyrimidines, with adenine pairing with thymine (in DNA) or uracil (in RNA) and guanine pairing with cytosine.
Pyrimidines and purines are two different types of nitrogenous bases found in nucleotides, which are the building blocks of DNA and RNA. Here are the key differences between pyrimidines and purines:
1. Structure: Pyrimidines consist of a single ring structure, while purines are made up of a double-ring structure. Pyrimidines have only one carbon-nitrogen ring, while purines have two fused carbon-nitrogen rings.
2. Composition: Pyrimidines include three different bases: cytosine (C), thymine (T), and uracil (U). In DNA, thymine is present instead of uracil. On the other hand, purines consist of two bases: adenine (A) and guanine (G).
3. Hydrogen Bonding: Pyrimidines form specific base-pairing interactions with purines. Cytosine (C) always pairs with guanine (G) through three hydrogen bonds, and thymine (T) (or uracil (U) in RNA) always pairs with adenine (A) through two hydrogen bonds. This hydrogen bonding is responsible for the complementary nature of DNA strands.
4. Molecular Weight: Purines are generally larger and heavier molecules compared to pyrimidines due to the presence of an extra ring in their structure.
5. Occurrence: Pyrimidines are more abundant than purines in DNA and RNA. In DNA, the ratio of purine bases (A and G) to pyrimidine bases (C and T) is usually close to 1:1. However, the exact ratio may vary between species.
Overall, the main difference between pyrimidines and purines lies in their structure, composition, and hydrogen bonding patterns. These differences enable specific base pairing and play a crucial role in the structure and function of DNA and RNA.