• Question: what is the difference between parasitic genomes and viral genomes?

    Asked by to Ditte, Ben, Dave, Heather, Rebecca on 17 Jun 2014. This question was also asked by .
    • Photo: Ditte Hedegaard

      Ditte Hedegaard answered on 17 Jun 2014:

      Hi parasite123

      That is a really good question. I think the biggest difference between the parasite and virus genome is the size. The smallest virus only has 2 genes, whereas a parasite like the malaria parasite has about 5,300 genes. This means that the malaria has a much more complicated life cycle and can survive without actually being inside a human. Viruses are one of the must primitive creatures on the planet and cannot produce new viruses outside the host cell. Once the virus has infected a cell it will take advantage of the cell’s activated genes and use them to produce new viruses. This way the viruses doesn’t have to have all the essential genes for survival, it can just use the cells genes. I actually think this is quite clever of the virus!

      Another difference is that parasite genes are made up of two lines of DNA, which are usually packed into x shaped structures called chromosomes, whereas viruses genome is either made of DNA or RNA and the genes can either be in two lines with base-pairs between the lines (this is explain in here /genomicsj14-zone/2014/06/17/what-is-a-base-pair/) or they can be in one line. Viruses are actually characterised by how their genes look, just like flowers are characterised by their shapes and colours. Another difference is that viruses do not have chromosomes; their genes are instead coiled up like a ball of wool inside the virus.

    • Photo: Rebecca Gladstone

      Rebecca Gladstone answered on 19 Jun 2014:

      A virus exhibits parasitic behavior (it uses another organism to survive) but isn’t a parasite.
      The type of organism called parasites belong to a group called Eukaryotes which is the same group that us humans and all animals also belong to, as we all have a structure in the centre of our cells called the nucleus where we keep our DNA.
      Viruses belong to a different group as they don’t have cells at all and store their DNA in a protein shell (capsid) and rely on the cells of other organisms to survive.

      Because viruses and parasite are so different their are key differences in their genomes too. They are diffferent in the way the genomes are:
      Stored – in a nucleus vs in protein capsid
      Organised – into coiled organised structures called chromosomes for parasites or just bundled inside the capsid for viruses.
      Size – parasite genomes are much bigger as they need genes to help them make new cells while viruses rely on the machinery in other organisms cells to copy themselves!
      Type – Parasites only have DNA genomes but viruses can have DNA or RNA genomes, they then convert their RNA in DNA using another organisms cells!

      All of these different features are detemined within the genome itself so they also have very different genes contained inside their genomes!

      Life is thought to have begun from virus like organisms they are very simple everything else is thought to have evolved from these virus like organisms, the modern viruses are still very simple whereas parasite genomes have many more functions and are also more complicated!

    • Photo: Ben White

      Ben White answered on 19 Jun 2014:

      As Ditte and Rebecca have explained below, parasites need more genes for things like metabolism and reproducing themselves (without using the host’s machinery). To help you understand the difference in size of these genomes, compared to each other and us, see this picture: http://tinyurl.com/m5mptjo

    • Photo: Dave Baker

      Dave Baker answered on 24 Jun 2014:

      Great answers!

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