DNA to RNA transcription
DNA is in the cell nucleus of eukaryotic cells, but although it contains the information necessary to make proteins and enzymes, they are synthesized in the cytoplasm. Since DNA cannot leave the nucleus, there has to be an intermediate molecule that carries information from a piece of the DNA chain, crosses the nuclear membrane and reaches the cytoplasm, where proteins are made. The mRNA or messenger RNA is the molecule that is responsible for copying the information from the nucleus DNA and taking it to the cytoplasm and being able to synthesize proteins.
ADN ———> ARN ———> PROTEÍNAS
The transcription or synthesis of RNA consists of the formation of an mRNA molecule whose sequence of nitrogenous bases is complementary to the sequence of nitrogenous bases of one of the two DNA chains that forms the double helix. That is to say:
- If the nitrogenous base in DNA is a C (cytosine), the complementary one in mRNA is a G (guanine).
- If the nitrogenous base in DNA is a G (guanine), the complementary one in mRNA is a C (cytosine).
- If the nitrogenous base in DNA is a T (thymine), the complementary one in mRNA is an A (adenine).
- If the nitrogenous base in DNA is A (adenine), the complementary one in mRNA is U (uracil) . Remember that RNA has U (uracil) instead of T (thymine).
This mRNA contains the information necessary to synthesize the protein in the cytoplasm .