Bacteria :: Science Chemistry Biology Experiment Essays

Bacteria Bacteria are the most common and ancient microorganisms on earth. nearly bacterium are microscopic, measuring 1 micron in length. However, colonies of bacterium grown in a laboratory petri dish can be seen with the unaided eye. There are many divisions and classifications of bacteria that assist in identifying them. The first two types of bacteria are archaebacteria and eubacteria. Both groups have common ancestors geological dating to more than 3 billion years ago. Archaebacteria live in environments where, because of the high temperature, no other life can grow. These environments include hot springs and areas of volcanic activity. They take over lipids but lack certain chemicals in their cell wall. Eubacteria are all other bacteria. Most of them are phototrophic, i.e. they use the suns energy as food through the process of photosynthesis. Another classification of bacteria is according to their need of oxygen to live. Those who do require oxygen to live are considered aerobes. The bacteria who dont use oxygen to live are known as anaerobes. The shape of specific bacteria provides for the next step in the identification process. Spherical bacteria are called cocci the bacteria that have a rodlike shape are known as bacilli corkscrew shaped bacteria are spirilla and filamentous is the term for bacteria with a threadlike appearance. Hans Christian Joachim Gram, a Danish microbiologist, developed a method for distinguishing bacteria by their different response to a stain. The process of applying Grams stain is as follows the bacteria are stained with a violet dye and treated with Grams solution (1 part iodine, 2 part potassium iodide, and 300 parts water). Ethyl alcohol is then applied to the medium the bacteria will either preserve the blue color of the genuine dye or they will obtain a red hue. The blue colored bacteria are gram-positive the red bacteria are place as gram-negative. Bacteria contain DNA (deoxyribonucleic aci d) just like all cells. However, in bacteria the DNA is arranged in a circular sort rather than in strands. Bacteria also contain ribosomes which, like in eukaryotic cells, provide for protein synthesis. In order for a bacterium to attach itself to a surface, it requires the aid of pili, or hairlike growths. Bacteria, just like sperm cells, have flagella which assist in movement. But, sperm cells only have one flagellum, whereas bacteria contain flagella at several locations throughout their body surface.