Expert: Chris Bemis - 11/24/2011

Question
QUESTION: Dear Expert,

I am Mr Washington. Well, I have a pretty stupid question that plagues me everytime I read about phages.
Why won't bacteria just develop resistance to bacteriophages, just like they did to our antibiotics?
Thank you.

Regards,
Washy

ANSWER: They do.  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC278397/

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QUESTION: Thanks for the article! Then, why don't our white blood cells mutate and develop resistance to HIV or any viruses like flue ( since we have been infected so many times by them)?

Regards,

Washy

ANSWER: Our white blood cells are not self-replicating like bacteria.  Rather, they only self-duplicate (by dividing into two identical daughter cells.  Bacteria do this too, but they also self-replicate and it is their rapid self-replication that allows them to so quickly take advantage of mutations that confer resistance.  In order for white blood cells to truly replicate (as opposed to simply duplicate) a sperm and egg must join to create a new human being (who will contain the new genetic version of white blood cells).  Because our cells are eukaryotic (as opposed to prokaryotic like bacteria), their genetic material is far more complex than that of bacteria.  Another site with good information:  http://www.ncbi.nlm.nih.gov/About/primer/genetics_cell.html

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QUESTION: Thank you! But since this is my first time learning about DNA and bacteria, can you pls tell me the difference between self-replicate and self-duplicate in a simplest way?  Thank you.

Regards,
Washy

Answer
Both bacterial cells and animal (eukaryotic) cells are capable of both cell division (duplication), in which one cell divides into two exact replicas of the original; and reproduction (replication) in which the genetic material from two different cells is combined to make a new organism.  

To further clarify, (quoted from website I sent in last post):

"Bacteria reproduce through a fairly simple process called binary fission, or the reproduction of a living cell by division into two equal, or near equal, parts. As just noted, this type of asexual reproduction theoretically results in two identical cells. However, bacterial DNA has a relatively high mutation rate. This rapid rate of genetic change is what makes bacteria capable of developing resistance to antibiotics and helps them exploit invasion into a wide range of environments.

Similar to more complex organisms, bacteria also have mechanisms for exchanging genetic material. Although not equivalent to sexual reproduction, the end result is that a bacterium contains a combination of traits from two different parental cells."