1. Storage:
* Nucleotides: DNA is composed of four building blocks called nucleotides: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T). These nucleotides are arranged in a specific sequence along the DNA molecule, like letters in a code.
* Double Helix: Two DNA strands, each a sequence of nucleotides, twist around each other to form a double helix. The two strands are held together by hydrogen bonds between specific base pairs: A pairs with T, and G pairs with C. This pairing ensures the information on one strand is mirrored on the other, providing redundancy and a mechanism for replication.
* Genes: Specific segments of DNA, called genes, contain the instructions for building and maintaining an organism. Each gene holds the code for a particular protein, which performs a specific function in the cell.
2. Transmission:
* Replication: Before a cell divides, it must duplicate its DNA. This process, called replication, involves unwinding the double helix and using each strand as a template to create a new complementary strand. The result is two identical DNA molecules, ensuring each daughter cell receives a complete copy of the genetic information.
* Transcription: The information stored in DNA is not directly used to build proteins. First, it needs to be transcribed into a messenger RNA (mRNA) molecule. This occurs within the nucleus, where an enzyme called RNA polymerase reads the DNA sequence and creates a complementary RNA copy.
* Translation: The mRNA molecule then travels out of the nucleus to the ribosomes, where it is translated into a protein. The mRNA sequence is read in groups of three nucleotides called codons. Each codon corresponds to a specific amino acid, the building blocks of proteins. Ribosomes use transfer RNA (tRNA) molecules to bring the appropriate amino acids to the ribosome based on the mRNA sequence.
In summary:
* Storage: DNA stores cellular information as a sequence of nucleotides. This information is organized into genes, each containing the code for a specific protein.
* Transmission: DNA replicates itself to pass on genetic information during cell division. Transcription and translation convert the DNA code into proteins, which perform essential cellular functions.
This remarkable system ensures the accurate and reliable transmission of genetic information from generation to generation, enabling life to flourish and evolve.
