Tuesday, April 21, 2015

How Bacterial Cells Recognize its own DNA

Bacteria cells have an immune system thats purpose is to fight off viruses known as phages. Its main goal is to determine what is a foreign substance and what is itself. Phages use the host cells replication to make its own copies of itself. It wasn't until recently that scientists discovered that bacteria had an adaptive system called CRISPR. This immune system mechanism is used to protect good bacteria and also can be used to edit the human genome. The system grabs and inserts a short sequence of the virus' DNA into the bacteria's genome. The pieces of DNA are stored in the immune memory of the genome. When it comes to other infections the CRISPR creates protein complexes that have RNA attached and identify the phage to destroy it.

 In previous research done by Dr. Sorek at the Weizmann Institutes Molecular Genetics Department showed the phage grabbing its own DNA. It was left with an autoimmune disease and ended up attacking its own DNA. Dr. Sorek and his student set up an experiment injecting plasmids into bacteria cells to see what a bacteria that had two proteins, Cas1 and Cas2, would do.  They found that the plasmid DNA was placed into the bacterial genome while the phage with its own DNA was not attacked. Although this does not prove whether or not CRISPR is good at determining self and non-self DNA, the Cas1 and Cas2 proves it has foreign DNA and is using its immune memory to activate defenses. 
This research is so incredible because bacterial cells are found everywhere and are so small. The research that they have done to discover that they have immune systems is amazing. Immune systems in human eyes are so complex and have so many factors added into them. The fact that they were able to discover their immune system to fight off viruses just proves how far science has come.

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