Bio Media Essay, Research Paper

How does chlorine added to drinking water kill bacteria and other harmful organisms? Why doesn’t it harm us?

Scientific American (Ask The Experts)

The article explains that although not much is known about how chlorine kills viruses and bacteria scientists hypothesize that in bacterial cells chlorine attacks the cell wall. By attacking the cell wall of a gram-negative bacterium (gram- positive bacterium are more tolerant, but most don?t pose a threat) chlorine severely increases the permeability of the outer membrane, leaving the bacterium vulnerable to destruction. What the experts know is that chlorine, if properly administrated to water, eliminates most waterborne pathogens. The reason chlorine is not very harmful to human cells is because when water reaches the tap it only has a little chlorine in it, enough to kill bacterial cells but not enough to harm human cells.

Greg Berkovich

1/20/01

Biology(per 8)

Ms. C

Questions:

1. What organisms kill the bacteria after its cell wall is damaged because of chlorine? How can they survive in chlorinated water?

2. Which is better chlorination or pasteurization?

3. Are there any other methods to destroy pathogens in water?

4. For what diseases is chlorine not effective?

Can bacteria adapt to chlorine like Anti-biotic medicines?