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AAT Bioquest

Why does DNA not form protein directly?

Posted February 4, 2021


Answer

DNA is responsible for forming protein, however it does not form protein directly. There are several reasons for this.

Firstly, DNA is packed very tightly. Unwinding it every now and then to facilitate protein translation would consume too much energy. In addition to being energy inefficient, there is also a high risk of loss of genetic material.

Secondly, protein translation occurs on ribosomes in the cytoplasm. For the DNA to produce proteins directly, it would have to translocate to the cytoplasm. During the process of translocating, the DNA could get damaged because of the osmotic nature of cytoplasm. To mitigate the damage, the cellular machinery does not use DNA to produce proteins directly. Instead, it uses mRNA as an intermediate to produce proteins.

Thirdly, because only a few areas of DNA code for a protein, it makes more sense to first convert protein coding regions to mRNA.

Secondly, most of the regions of DNA do not code for a protein so more time is spent searching for coding regions. It is more logical to first convert protein coding regions to mRNA.

Downsides of DNA directly translate into protein may include:

  • Very low production of proteins
  • Neither time nor energy efficient
  • Higher risk of DNA damage
  • Higher risk of histones sliding
  • Very high energy consumption for the DNA to translocate to the cytoplasm where protein translation occurs
Additional resources

DNA, RNA and protein interactions

Polymerase Chain Reaction (PCR)

6-ROXtra™ fluorescence reference solution *25 uM for PCR reactions*