So - what's this exciting thing Mom is reading about in biology these days?
I was, of course, humbled when I heard that Campbell and Reece put in an entire chapter about ME in their Biology book. I'm unique and particularly beautiful/handsome/scary/awe-inspiring etc.. but I still was surprised they'd gotten around to writing about me quickly - but apparently my reputation travels fast.
Then Mom pointed out that it was not really about ME.. It's about viruses in general. I didn't even know there was a general form of me!? But apparently she was talking about a group of thingies that must have been named after me. Anyhow - I thought you would like to know a thing or two about my namesakes.
So here is Virus' guide to Viruses!
Viruses, unlike myself, are not alive - but they are able to replicate themselves (with a little help from a friend) so they're a bit of a borderline case. They consist of nucleic acid (we cats (and dogs and hoomans) have DNA, viruses can have either DNA or RNA) wrapped up in a protein coat.
They take various shapes, this one here is called a phage
I think it's the virus most like me because it's got a head and a tail, and so do I. He stores his DNA in his head.
I mentioned he needed a friend to replicate himself. You see - you need all sorts of tiny intercelluar gadgets and supplies to make protein (for new heads and tails and so on) and to make copies of the DNA to put into baby viruses.
So - when the virus encounteres a cell it's compatible with (you see - they're a bit spesific about what cells they want to interact with. Or.. they only know the secret code to be let into one or a limited kind of cell) it will send its DNA into the cell where the cells mecanisms will help it to make many more viruses. But the virus(es) isn't a very nice guest and will eventually make the cell die and fall apart releasing the baby viruses into the world. This is called a lytic cycle.
There is another option - and that is for the virus to sneak its DNA into the DNA of the cell allowing the cell to continue as usual. The cell will divide to make more cells when needed - and they will also copy the virus DNA into the new cells. This is called a lysogenic cycle. Sometimes if a cell is triggered in the right way the virus DNA will leave the cells DNA and bring the cell into a lytic cycle. This is for instance the case with herpes virus in humans, where you have occational outbreaks, but even when you have no symptoms the virus is still in your cells in that area.
Now I think that's about as much as you'd care to learn about viruses, huh? ;) But one more thing - when we're sick because of a virus - for instance the flu - the symptoms we feel are rarely related to the virus (destroying cells and all), but side effects of our immune system. The immune system is the good guys that step in to evict the virus and make us all better. :)
Oh.. and you get oh-so-cute virus toys! Mom so want some of these...
This is common cold:
This is E Coli - he's a bit more scary looking, really...
You find the others here: http://www.thinkgeek.com/geektoys/plush/6708/images/770/ (thats where I stole the picture.. I'm a Virus too, after all, so I don't think they'd mind - with me giving them ad space and all).
Virus free (i think) Virus