Lonic Chida
Nov 13, 2023
With examples, differentiate between purins and pyrimidines?
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Nov 13, 2023
Purines and pyrimidines are two types of nitrogenous bases found in DNA and RNA molecules. They are the building blocks of nucleotides, which are the monomers that make up DNA and RNA. Here are some examples and differences between purines and pyrimidines:
1. Structure:
- Purines: Purines have a double-ring structure consisting of a six-membered ring fused to a five-membered ring. The two rings are called pyrimidine and imidazole rings. Examples of purines include adenine (A) and guanine (G).
- Pyrimidines: Pyrimidines have a single-ring structure consisting of a six-membered ring. Examples of pyrimidines include cytosine (C), thymine (T) (found in DNA), and uracil (U) (found in RNA).
2. Number of Nitrogen Atoms:
- Purines: Purines contain four nitrogen atoms in their structure.
- Pyrimidines: Pyrimidines contain two nitrogen atoms in their structure.
3. Base Pairing:
- Purines: In DNA, adenine (A) always pairs with thymine (T) through two hydrogen bonds. In RNA, adenine (A) pairs with uracil (U) through two hydrogen bonds.
- Pyrimidines: In DNA, cytosine (C) always pairs with guanine (G) through three hydrogen bonds.
4. Molecular Weight:
- Purines: Purines have a higher molecular weight compared to pyrimidines due to their double-ring structure.
- Pyrimidines: Pyrimidines have a lower molecular weight compared to purines due to their single-ring structure.
5. Presence in DNA and RNA:
- Purines: Adenine (A) and guanine (G) are present in both DNA and RNA.
- Pyrimidines: Cytosine (C) and thymine (T) are present in DNA, while cytosine (C) and uracil (U) are present in RNA.
Overall, purines and pyrimidines differ in their structure, number of nitrogen atoms, base pairing, molecular weight, and presence in DNA and RNA. These differences contribute to the unique properties and functions of these nitrogenous bases in nucleic acids.
1. Structure:
- Purines: Purines have a double-ring structure consisting of a six-membered ring fused to a five-membered ring. The two rings are called pyrimidine and imidazole rings. Examples of purines include adenine (A) and guanine (G).
- Pyrimidines: Pyrimidines have a single-ring structure consisting of a six-membered ring. Examples of pyrimidines include cytosine (C), thymine (T) (found in DNA), and uracil (U) (found in RNA).
2. Number of Nitrogen Atoms:
- Purines: Purines contain four nitrogen atoms in their structure.
- Pyrimidines: Pyrimidines contain two nitrogen atoms in their structure.
3. Base Pairing:
- Purines: In DNA, adenine (A) always pairs with thymine (T) through two hydrogen bonds. In RNA, adenine (A) pairs with uracil (U) through two hydrogen bonds.
- Pyrimidines: In DNA, cytosine (C) always pairs with guanine (G) through three hydrogen bonds.
4. Molecular Weight:
- Purines: Purines have a higher molecular weight compared to pyrimidines due to their double-ring structure.
- Pyrimidines: Pyrimidines have a lower molecular weight compared to purines due to their single-ring structure.
5. Presence in DNA and RNA:
- Purines: Adenine (A) and guanine (G) are present in both DNA and RNA.
- Pyrimidines: Cytosine (C) and thymine (T) are present in DNA, while cytosine (C) and uracil (U) are present in RNA.
Overall, purines and pyrimidines differ in their structure, number of nitrogen atoms, base pairing, molecular weight, and presence in DNA and RNA. These differences contribute to the unique properties and functions of these nitrogenous bases in nucleic acids.
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