Messenger RNA (mRNA)

mRNA strand

Here is an excerpt of an mRNA strand. It does not have a double helix like its DNA counterpart, and uracil (represented by ‘U’) is used instead of thymine (represented by ‘T’). The black text in the image denotes an amino acid/start codon.

Messenger RNA (mRNA) is the molecular blueprint used by the cell to make proteins from amino acids. In a process called transcription, DNA is copied by a machine called the RNA polymerase to produce a strand of mRNA. mRNA is then released to be translated into an amino acid chain which then becomes a protein when folded.

mRNA consists of four nucleotide building blocks as in DNA, but with uracil used in place of thymine, and has a lifetime of anywhere between a few seconds in bacteria to days in mammals. As with DNA, every three bases, or ‘letters’, make up a codon. And every codon in the strand calls for an amino acid — all of which are joined together to create a polypeptide during translation.

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