Monday, October 1, 2007


Scientist classify all organisms into different groups. Originally the Five Kingdom System was used. This system was divided into Monera, Protists, Plants, Fungi, and Animals. After genetic comparisons and study, a new system was created, known as the Domain System. Monera, from the kingdom system, was separated into bacteria and archaebacteria. Then, the other domain is Eukaryotes, which contains protists, plants, fungi, and animals. The protist group is very diverse and therefore this classification system may soon be changed again as more information is found on protists.

Old 5 Kingdom System

New 3 Domain System


Bacteria live everywhere, on and in plants and animals, in soil, oceans, extreme temperatures, on living and on the dead. There are also several different kinds of bacteria, including bacillus, bordetella, clostridium, escheichia ( also known as E. coli), spirulina, staphylococus, streptococus, and salmonella.

The structure of a prokaryotic cell can be bacillus ( straight and rod-shaped), coccus( spherical shaped), and spirillium ( long and helical shaped). Prokaryotes are unicellular, but sometimes individual cells will adhere to eachother forming a matrix. Even though they are attached, each cell still retains its individuality. The cell size of prokaryotes is 1/10 that of eukaryotes, and the internal structure contains no internal compartments and no membrane bound organelles. Variations can be seen within cell interiors of different prokaryotes. Cyanobacterium contains internal membranes so that it can go throught the process of photosynthesis, wheras aerobic bacterium's internal structure allows it to respirate.

Prokaryotes can either be Gram-positive bacteria or Gram-negative bacteria. The Gram positive bacteria have a thicker peptidoglycan wall and stain a purple color while the Gram-negative bacteria contain less peptidoglycan and do not retain the purple colored dye. Gram-negative bacteria are more harmful than Gram-positive bacteria because they are more resistant to antibiotics.

Prokaryotic Metabolism:

Bacteria get their energy and nutrients one of two ways. Either they are autotrophs or heterotrophs. Photoautotrophs are photosynthetic bacteria such as cyannobacteria, and they produce their own energy throught the process of photosynthesis. Chemoautotrphs also make their own energy and nutrients through the process of oxidation of inorganic compunds such as nitrogen, sulfur, hydrogen, and others. Heterotrophs live on plant and animal matter. They are known as decomposers or pathogens. Pathogens are disease causing organisms. Decomposers are very helpful to our environment because they feed off of dead organisms and then put the energy from them back into the environment.

Bacteria reproduce asexually every twenty minutes. Mutations can occur very quickly in bacteria because of their ability to rapidly reproduce. Genetic Recombination is when bacteria swap genes.

Good Bacteria vs. Bad Bacteria

There are both good and bad bacterias. There are disease causing microbes which cause plant and animal diseases such as fruit rotting, blights and wilts. Animal diseases include tooth decay, ulcers, anthrax, botulism, plague, leprosy, STDs, typhoid, pneumonia and lyme disease. Leprocy is one of the scariest diseases to observe. Good bacterias are decomposers ( if there were no decomposers, life one arth would cease). Good bacteria also aid digestion (E.coli) because they have a cellulase enzyme and digest cellulose in herbivores and also produce Vitamins K and B12 for humans, which is crucial to live. Also, good bacterias produce foods and medicines, such as yogurt and insulin.

This is a video I found on bacteria...

Tomorrow's Sherpa is Seung

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