• Question: what is the most complicated strand of DNA

    Asked by trivorowo to Craig, Laura, Saffron on 26 Jun 2015.
    • Photo: Laura Wales

      Laura Wales answered on 26 Jun 2015:

      For a cell to reproduce, it needs to replicate/make a copy of its DNA. Each side of the double helix run in opposite directions. The leading strand goes from 5′ to 3′. The lagging strand goes from 3′ to 5′. The double helix untwists and unzips so the two strands are free and both these strands provide a template to add new strands onto.

      Synthesis of the lagging strand is more complicated, because DNA polymerases can add nucleotides only to the 3′ end of a primer (or growing DNA strand). Here’s why I think it’s more complicated:

      Once the double helix unzips, short strands of RNA are generated and they bind to the single-stranded DNA to initiate DNA synthesis by the enzyme, DNA polymerase. This enzyme can work only in the 5′ to 3′ direction, so it replicates the leading strand continuously. Lagging-strand replication is discontinuous, with short newly formed fragments being formed and later linked together.

    • Photo: Craig Doig

      Craig Doig answered on 26 Jun 2015:

      trivorowo

      DNA is super complicated and we have only known about its structure for the last 50 years or so. (sounds like a long time but its not! )

      Humans have really complicated DNA. But its not just your DNA thats important, its also the way the DNA gets used.

      For example if you take identical twins when they are born and put one in the U.S.A to live (where there is lots of bad unhealthy food). and put the other one in Japan where there is lots of healthy food (fish, vegetables).

      Once they are adults it is likely that USA twin will be fat or obese and have a reduced life expectancy. Japan twin will be lean healthier and probably live longer than USA twin !

      So even with the same DNA you can be very different…. thats how complicated DNA is !

Comments