• Question: 2) When analysing genetic sequences, what are you actually aiming to find out? Is it a mutation, or a certain sequence etc.?

    Asked by elle letters to Theresa on 2 Jul 2020.
    • Photo: Theresa Wacker

      Theresa Wacker answered on 2 Jul 2020:

      Hi again,
      thanks for the brilliant question!
      Essentially, genetic sequence analysis can encompass many things:
      a) you can look at the genome as a whole and look at genome architecture. You can look at one genome and try to find out how many chromosomes there are, how many sets of chromosomes we have (ploidy), whether individual chromosomes are duplicated or lost (within one set of chromosomes, trisomy is a good example), whether there have been translocations from one chromosome or not etc.. You can then look at two genomes and compare them, to see how for instance closely related species are similar or different to each other and how that relates to physiological, ecological etc. differences between them. This might also explain differences in virulence, for instance.
      b) you can look at individual genes, whether there are mutations within a gene, whether the gene has been duplicated (which might be relevant for virulence, as having more of for instance a transporter that transports drugs like antibiotics out of an organisms might render them resistant to that drug), whether there is a linkage between different genes etc..
      c) you can look at gene expression and relate that to adaptation to certain environmental conditions. When a fungus enters the body, which genes does is upregulate and downregulate and can these genes for instance be targets for drugs? Some fungi upregulate enzymes that make them less susceptible to attacks by immune cells and if you block that upregulation, the immune system might effectively fight them.
      d) you can look at chromatin structure. Eukaryotic DNA is wrapped on proteins that are called histones. You can think of them like hair curlers and DNA is wrapped around them like hair. Now, if the DNA is wrapped tightly around them, it is inaccessible and genes that are on that bit of the DNA cannot be expressed. Conversely, other bits might not be as tightly wrapped and accessible. You can look at that and how it changes in response to different conditions, like when a fungus encounters lots of nutrients vs. when it is starved or different temperatures for instance.
      As you can see, there is maaaaaany things you can try to find out when looking at genomic sequences. What I described is only a tiny fraction of it! Exciting, isn’t it?
      I hope that answers your question 🙂

Comments

  • mayakrawi commented on :

    It depends on the question you are looking to answer. DNA sequencing and its subsequent analysis is only a tool you use to solve many puzzles. You can be sequencing the DNA of a new species, or looking for a certain mutation or a answering a variety of other questions that pertain to evolution or disease.