DNA Unit is Called: Nucleotides
The fundamental building block of DNA is called a nucleotide. Think of it like a single letter in a very long sentence that codes for life. Each nucleotide is composed of three parts:
1. A Deoxyribose Sugar:
This is a five-carbon sugar molecule. It's the "backbone" that holds the whole nucleotide together. The deoxyribose sugar in DNA is different from the ribose sugar found in RNA, which is a key distinction between the two nucleic acids.
2. A Phosphate Group:
This is a negatively charged group containing phosphorus, oxygen, and hydrogen atoms. The phosphate groups link the deoxyribose sugars together, forming the sugar-phosphate backbone of the DNA double helix. This backbone is crucial for the DNA's structural stability.
3. A Nitrogenous Base:
This is the variable part of the nucleotide and is what determines the genetic code. There are four types of nitrogenous bases in DNA:
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T)
These bases pair up in a specific way: Adenine always pairs with Thymine (A-T), and Guanine always pairs with Cytosine (G-C). This specific base pairing is crucial for DNA replication and the transmission of genetic information.
In summary: A nucleotide is a complete unit consisting of a deoxyribose sugar, a phosphate group, and one of the four nitrogenous bases (A, T, G, or C). The sequence of these nucleotides along the DNA strand determines the genetic information encoded within the DNA molecule. Millions of these nucleotides strung together make up the entire DNA molecule, forming the blueprint of life.
