• Question: how do diseases attack our DNA?

    Asked by anon-244767 on 29 Apr 2020.
    • Photo: Alena Pance

      Alena Pance answered on 29 Apr 2020:

      Some diseases are already in our DNA. These are changes in the DNA of our parents that are therefore transmitted to us, so the disease is already there. But since we receive half of our DNA from each parent, we have a chance that the mutation or change will be in only one half and then we might not suffer the disease because many times diseases only happen when both halves of the DNA have the particular change.
      Other things, like environmental factors, can induce changes in our DNA ‘attacking it’ in a way. For example the sun emits uv radiation that can penetrate our tissues, specially the skin, and our cells getting all the way into the nucleus, where it breakes the DNA. Our cells have a very efficient repair machinery but it is not error-free and so some of this damage can be permanent. Some chemicals can cause chemical modification of the DNA molecule, which can change the way the genetic machinery works.

    • Photo: Gavin McStay

      Gavin McStay answered on 29 Apr 2020:

      Some diseases are caused by mutations in proteins that affect the amount of nucletides, DNA building blocks, in a cell. If there are not enough nucleotides in a cell then DNA can not be copied or repaired properly. This results in more mutations or not enough DNA in the cell – if this happens these cells can not function properly and the cells usually die leading to tissue failure an disease.

    • Photo: Sophie Pritchard

      Sophie Pritchard answered on 30 Apr 2020:

      Viruses from the outside environment can enter our bodies, and they’re able to enter our cells and access the DNA within our nucleus. They can take over the DNA replication system in our cells, which normally control the duplication of our DNA and division into new cells. The virus’ are basically an unwanted intruder. They use our systems to replicate themselves, and cause our healthy cells to die. Thankfully we have robust immune systems which send out an army of white blood cells to attack these viruses, minimising the impact on our cells.

      Bacteria do not need our cells to be able to reproduce like viruses do, but they also have their own methods of affecting our DNA. They can turn certain genes on or off. If these are essential genes for the cells survival, turning them off, may cause the cells to die. Bacteria can also induce mutations (changes in our DNA), which can alter the behaviour and function of our cells, and maybe their ability to survive.

    • Photo: Angela Downie

      Angela Downie answered on 30 Apr 2020: last edited 30 Apr 2020 10:12 pm

      Thankfully for us our DNA tends to be very well protected, coiled up inside the nucleus. This means that most of the time when virus or bacteria enter our body, even though we become sick our DNA will be safe. However, there are certain viruses that can put their own DNA into our genomes. This is called integration and it is very rare, an example of this being HIV.
      As others have pointed out, some diseases happen after our DNA becomes damaged by the environment. One disease that is very linked to DNA damage is cancer. When our DNA becomes damaged by things like UV light from the sun, or nicotine in cigarettes, errors can be introduced into our DNA. Most of the time our cells will catch this and stop any cell with damaged DNA from dividing. However the more mistakes a cell has the harder it is to do this, so after a while some of these cells start dividing when they shouldn’t, carrying these mistakes with them and generally misbehaving.

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