1. Nucleotide Structure:
* Nucleotides are the building blocks of nucleic acids. They consist of a sugar molecule (ribose in RNA, deoxyribose in DNA), a phosphate group, and a nitrogenous base.
* There are four different nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T) in DNA; uracil (U) replaces thymine in RNA.
* The sequence of these bases along a nucleic acid strand is what determines the genetic code.
2. Base Pairing Rules:
* Specific base pairing rules govern how nucleotides interact. Adenine always pairs with thymine (A-T) in DNA and uracil (A-U) in RNA. Guanine always pairs with cytosine (G-C).
* These pairings are based on hydrogen bonding between the bases, ensuring the correct pairing and maintaining the integrity of the double helix structure in DNA.
3. Genetic Code:
* The sequence of nucleotides within a gene (a segment of DNA) dictates the sequence of amino acids in a protein. Each group of three consecutive nucleotides, called a codon, codes for a specific amino acid.
* The genetic code is universal, meaning it is essentially the same in all living organisms. This allows for the translation of DNA into proteins with high fidelity.
4. Information Storage and Transmission:
* Nucleotides store genetic information in the order of their bases. This information is passed down from generation to generation through DNA replication.
* During protein synthesis, the genetic code is transcribed from DNA into RNA, which is then translated into a protein.
In summary:
The specific sequence and structure of nucleotides in nucleic acids create a code that carries genetic information. This code is based on the four nitrogenous bases and the specific base pairing rules, allowing for the accurate transmission of genetic information from one generation to the next and the translation of DNA into proteins.
