DNA replication, transcription, and translation are the three key processes involved in the transfer of genetic information from DNA to protein.
- DNA Replication: DNA replication is the process by which DNA copies itself to produce two identical strands. The process occurs in the nucleus of a cell and is initiated by an enzyme called DNA helicase, which unwinds the double helix structure of DNA. This creates a replication fork, which is then stabilized by other proteins. Another enzyme called DNA polymerase then adds new nucleotides to each of the separated strands, using the existing strands as templates. The result is two identical DNA molecules, each with one strand from the original DNA molecule and one newly synthesized strand.
- Transcription: Transcription is the process by which DNA is converted into RNA, specifically messenger RNA (mRNA). This process occurs in the nucleus of a eukaryotic cell, or in the cytoplasm of a prokaryotic cell. The process is initiated by an enzyme called RNA polymerase, which binds to a specific region of DNA called the promoter. The RNA polymerase then unwinds the double helix of DNA and adds RNA nucleotides to the growing RNA strand, using the DNA strand as a template. The process continues until the RNA polymerase reaches a termination signal on the DNA, and the newly synthesized mRNA is released.
- Translation: Translation is the process by which mRNA is translated into a protein. This process occurs in the cytoplasm of a cell and is carried out by ribosomes. Ribosomes read the codons on the mRNA and use them to assemble amino acids in the correct sequence to form a polypeptide chain. Each codon specifies a particular amino acid, and the order of the codons on the mRNA determines the order of the amino acids in the protein. The process continues until the ribosome reaches a stop codon on the mRNA, at which point the polypeptide chain is released.
These three processes are fundamental to the transfer of genetic information from DNA to protein, and they form the basis of many of the complex molecular interactions that underlie biological systems.