The central dogma is a fundamental principle in molecular biology that describes the flow of genetic information within a cell. It explains how genetic information is transferred from DNA to RNA and then translated into proteins. The central dogma can be summarized in three main steps:
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DNA Replication: During cell division, DNA molecules are duplicated through a process called DNA replication. The two strands of the DNA double helix separate, and each strand serves as a template for the synthesis of a new complementary strand. This results in two identical DNA molecules, each containing one original and one newly synthesized strand.
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Transcription: The genetic information stored in DNA is transcribed into RNA in a process known as transcription. RNA polymerase, an enzyme, binds to a specific region of DNA called a promoter and unwinds the DNA double helix. It then synthesizes a single-stranded RNA molecule, called messenger RNA (mRNA), by using one of the DNA strands as a template. The mRNA molecule is complementary to the DNA template strand, with the exception that RNA uses uracil (U) instead of thymine (T) as a base pair for adenine (A).
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Translation: The mRNA molecule carries the genetic information from the nucleus to the cytoplasm, where it serves as a template for protein synthesis during translation. Ribosomes, the cellular machinery responsible for protein synthesis, attach to the mRNA molecule and read the genetic code in groups of three nucleotides called codons. Each codon corresponds to a specific amino acid. Transfer RNA (tRNA) molecules bring the appropriate amino acids to the ribosome, based on the codons on the mRNA. The ribosome links the amino acids together in the correct sequence, forming a polypeptide chain, which folds into a functional protein.
In summary, the central dogma states that genetic information flows from DNA to RNA through transcription and from RNA to proteins through translation. This fundamental concept underlies the mechanisms by which genetic information is stored, transmitted, and expressed in living organisms.
