Mets Cell Community

Bad Bacteria: Escherichia Coli

Escherichia Coli, more commonly known as E. coli, is a bacteria that can be found in the large intestine of warm-blooded organisms. It can be totally harmless, and in some cases helpful by producing vitamin K. However, there are also many other cases where E. coli can be a harmful bacteria, and in some cases even lethal. Harmful E. coli usually only causes mild disease in humans, but it can be life threatening to children, the elderly, and immunocompromised people.





          E. coli is a fairly simple structured bacteria. It is a bascillus bacteria meaning that it is rod-shaped (see the picture to the right). The inner part of the cell contains cytoplasm, and in the cytoplasm DNA is stored. There is a cell membrane that surrounds the inner components of the cell, and many, but not all E. coli bacteria have a flagellum.


          There are many different strains of E. coli, some harmful and some harmless. Each strain is different in it's characteristics. There are many different strains of E. coli because E. coli is strongly drug resistant and is constantly evolving to avoid the antibiotics that are used to try and fight it (such as streptomycin or gentamicin.) The strong drug resistance of E. coli can make it hard to fight, but when diagnosed early on, there are many existing drugs that can identify, locate, and exterminate the harmful strains of E. coli in you. E. coli can cause a variety of diseases, and also a wide range of severity of these diseases depending on age, immune system effectiveness, how early it is diagnosed, and how well and properly it is treated.


Sources:
http://en.wikipedia.org/wiki/Escherichia_coli
http://www.lbl.gov/Publications/Currents/Archive/Mar-05-2004.html
http://science.howstuffworks.com/environmental/life/cellular-microscopic/cell1.htm

Investigation of Living Things: Lab Reflection

         In the Investigation of Living Things lab, we took different foods (Egg whites, egg yolks, apples, onions, potatoes, lemons, and strawberries), and did different tests to each of them which identified if the food had protein, starch, glucose, or lipids, depending on the test. In the test for protein we added 10 drops of a solution that identifies protein in substances called Biuret solution, to 5mL of the food and waited to see if the test was positive of negative. The Biuret solution itself is blue, but after a while, a caramel-brown color should appear on the sides of the test tube if the food contains protein. If nothing happens then that food does not have protein. In the glucose test we added 3mL of Benedict's solution to 5mL of the food, and then heated the test tube that they were in for 5 minutes. If the test was positive, the color in the test tube should have changed dramatically, into a sort of cool orange/red/yellow color. In the starch test we added 5 drops of Lugol's iodine solution to 5mL of the food, and if it tested positive then the color in the test tube should have turned a dark black. And lastly, in the test for lipids we smeared some of the food onto a piece of brown paper, let it dry over night, and then observed the piece of paper the next day. If the test was positive, when held up to light a glossy cover should be visible where the food was smeared.

         I thought that this was a cool lab because it applied what we had learned about macromolecules to foods that we eat on a daily basis. I had always just thought that an apple was an apple, and that was it, but after doing this lab i realize that an apple contains glucose and starch, and is made up of millions of microscopic cells all bonded together. I think it was a fun and active way to put what we had learned in chapter one in perspective, and to really put the idea in our heads that everything in the world is made up of cells, which are made up of many different atoms, elements, molecules, and macromolecules which we have just started learning about.