Microbiology question

[spatch]

For a bio project I have to investigate a virus and I was wondering...

If a virus is non-living and doesnt respond to stimulis, how does it evolve?

 

[mab904]

Viruses can not reproduce or evolve themselves without “help”. Help comes in the shape of a host cell where a virus latches onto with its “tails”. It then injects its genetic material into the host cell. Other viruses have the capacity to simply dissolve the cell wall, and “sink” into it.. Once the DNA of the virus is inside the cell, it takes control of it and forces it, using its resources, to produce more of the same virus DNA and parts of the virus. When most of the cell is used up to produce more virus material, it becomes is so weakened that it bursts like a soap bubble, releasing the new replicated viruses which immediately seek out new host cells to invade and destroy. This is essentially how viruses spread through the body. Luckily, in most cases viruses just attack one particular kind of cell.

 

[mab904]

here's a cool link:

http://www.virology.net/garryfavweb.html

 

[King Nothing]

I'm quoting this out of my bio book. I typed it fast so may have some errors:

"Today, the mutation of existing viruses is a major source of new viral diseases. The RNA viruses tend to have an unusually high rate of mutation because the replication of their nucleic acid does not involve proofreading steps, as does DNA replication. Some mutations may enable existing viruses to evolve into new genetic varieties that can cause disease in individuals who had developed immunity to the ancestral virus. Flu epidemics are caused by viruses that are genetically different enough from earlier years' viruses that people have little immunity to them.

Another source of new viral deiseases is the spread of existing viruses to a new host species. For example, hantavirus is common in rodents, especially deer mice. The population of deer mice in the southwestern United States exploded in 1993 after unusually wet weather increased the rodents' food supply. Humans acquired hantavirus when they inhaled sut containing traces of urine and feces from infected mice.

Finally, a viral disease may start out in a small, isolated population and then rather suddenly become widespread. AIDS, for example, went unnamed and virtually unnoticed for decades before starting to spread around the world. In this case, technological and social factors, including affordable international travel, blood transfusion technology, sexual promiscuity, and the abuse of intravenous drugs, allowed a previously rare human disease to become a global epidemic. It is likely that when we do find the means to control HIV and other deadly viruses, genetic research--in particular, molecular biology--will be responsible for the discovery."

Campbell, Neil, Jane Reece, and Eric Simon. Essential Biology with Physiology. San Francisco: Pearson Education, Inc., 2004. 192-193.

 

[King Nothing]

Your probalby lookin for more info though on the first paragraph. I hope someone else can help us out with this

 

[Matthew D]

Mab is basically right about but there is one other way that some viruses infect cells, especially bacteria. The use of plamids to insert a specific short snippet of DNA or RNA into the bacteria. This allows the virus's genetic information to be reproduced and this is one of the reasons that some virus lay dormant for a period of time only to reappear. The processes described by MAB is called the Lytic phage and the one I described is called the Lysogenic phage.

 

[x_muscle]

Look into bacterial transofmation, and viruses.

Some viruses mix it genetic material with the host genetic material, and some times errors in viral replication with host evolve and create new strains of virsus.

an example of that is the avian flu virus H5N1, which mixed it genetic material with regular influnza in a host allowing human to human mode of transmition.

I just finished a 5 units class of micrbiology, and i have a full chapter on this subject.

If you need further help just let me know.

 

[x_muscle]

The processes described by MAB is called the Lytic phage and the one I described is called the Lysogenic phage.

yep, Lytic mode of replication is what usually allow virsus to evolve, since virsus genetic material stay with hst genetic material, and replicate with it. Some times parts of host genetic material stick with virus DNA or RNA creating new strains possibly more pathogenic.

 

[Matthew D]

X muscle are you sure about that.. lyogenic life cycle allow for the transmission of encoded genetic information to be passed on, lytic life cycle allow for the quick transmission and the death of the host cell since the virus uses all of the host cell's internal processes to replicate itself.
I also have quite a bit of information on the subject if you need. I was going to upload one of my sets of notes from my non-major's class I teach for nursing students.