• Question: When a gene is sequenced what information do you get? Just the sequence of bases or more?

    Asked by shoran to St Kilda Wren, Scotch Thistle, Hazel Dormouse, Emperor Dragonfly, Common Crane, Catshark, Brown garden snail, Barn Owl on 21 Nov 2017.
    • Photo: Emperor Dragonfly

      Emperor Dragonfly answered on 21 Nov 2017:

      Ultimately, that is exactly what “DNA sequencing” means – determining the order of DNA bases along a gene, a chromosome or a genome. BUT once we have that order we can do a lot with it that tells us so much more… we can compare the sequence we have with other species to see how it differs, or even whether that gene is new to the species we sequences, and is like nothing else in our database (which is very exciting!). My scientist is particularly interested in DNA sequences that can be found in lots of different organisms but are not really regular genes – they are more like “molecular fleas” that spread around genomes over time, often taking up a huge amount of space – your DNA is about half “molecuar fleas”! One reason to sequence the Emperor Dragonfly genome is that it is much bigger than we might expect, usually sign of a big molecular flea infestation, but one that has not stopped dragonflies from being wildly successful and incredibly long lived, in evolutionary terms.

    • Photo: St Kilda Wren

      St Kilda Wren answered on 21 Nov 2017:

      Looks like Emperor Dragonfly nailed it. Apart from sequencing their genome – ours is much more interesting. 😉

    • Photo: Lesser-Spotted Catshark

      Lesser-Spotted Catshark answered on 22 Nov 2017:

      The winner of this competition will have a ‘reference genome’ produced. This will be, as you say, essentially a long sequence of bases (or rather several long sequences broken into different numbers of pieces – either whole chromosomes or smaller fragments called contigs). To produce a reference genome we will use DNA from one individual but remember most animal genomes are diploid meaning they have 2 copies of every chromosome (one from each parent). When we obtain the genome sequence we will effectively sequence both of these copies. This will show regions where the DNA is the same or ‘homozygous’ (e.g. an ‘A’ in both the paternal and maternal chromosome) and areas where the DNA is different or ‘heterozygous’ (e.g. an ‘A’ in the paternal copy and a ‘G’ in the maternal copy). These differences within an individual are called ‘polymorphisms’ and every one of us has them – its what makes one individual different from another and is a key part of studying animal (and human) populations.

    • Photo: Common Crane

      Common Crane answered on 23 Nov 2017:

      I will divulge a small secret with you. Those, who will sequence common cranes, will find quite a few aces among all those bases 😮