Trihelical DNA?

Hollywood often gets genetics wrong and one example is the bizzare idea that species can evolve under drastically different cirtcumstances and this creates 3 helices. This has been true from Species. The concept has crept into video games with Assassin’s Creed Isu having a third DAN strand. This was said to make the species more capable. The question is one of practicalities.

DNA as a rule is made of 4 nucleotides, guanine, cytosine, thymine and adenine. These are able to produce all of the effects seen from DNA alone. This effec tis facilitated by opening and closing the DNA double helix. A complex process this has 7 components just to unwind the helix.

Imagine how many it might be required to open and maintain a tri helcial structure.

There are other issues too. The most fundamental is what would be gained by adding another strand. A large investment of time and energy that has no obvious adavantage and many risks.

Relevant links:

Wiki: Triple-stranded DNA
https://en.wikipedia.org/wiki/Triple-stranded_DNA

DNA Triple Helices: biological consequences and therapeutic potential
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2586808/

Do DNA Triple Helices or Quadruplexes Have a Role in Transcription?
https://www.ncbi.nlm.nih.gov/books/NBK6417/

Stable Triple-Stranded DNA Formation and its Application to the SNP Detection
https://academic.oup.com/dnaresearch/article/12/6/441/344455

Replication fork components
https://www.nature.com/scitable/content/replication-fork-components-14463312/