Tuesday, October 2, 2007


In the old classification system, there was the:
  • Monera
  • protists
  • plants
  • fungi
  • animals
There is now a Three Domain system which includes:
  • Bacteria
  • Archaebacteria
  • Eukaryote - which includes:
  1. protists
  2. plants
  3. fungi
  4. animals
-In this new classification, the Monera has split into the bacteria and archaebacteria which are more different than humans and plants.

- We learned that bacteria are everywhere! which means they are on our and animals bodies, in our bodies, in the soil, in the ocean depths, in extreme environments, and on the dead as well as the living.
This is a volcanic vent in the ocean; an example of one of the extreme conditions bacteria live in. They form colonies on the vents and get energy from the sulfur gas being released.

- The main bacterial shapes are rods, spheres, and spirals.

-Prokaryotes are unicellular and lack internal organization. They possess no endoplasmic reticulum, vesicles, mitochondria, or chloroplasts. They do however have ribosomes.
- Prokaryote cells are 1/10 the size of eukaryotes and have a "naked" DNA. Their DNA is not wrapped around proteins like ours.

Variations in Cell Interior
In Cyanobacterium bacterium or photosynthetic bacterium, there is an enfolding of the external membrane. The enzymes involved in photosynthesis are located in the membranes, so with the more enfolding, the more photosynthesis and energy and sugar will be produced.
- In Aerobic bacterium the membrane contains enzymes involved in respiration. Therefore, the more enfolding the more energy will be produced.

Prokaryote Cell Wall Structure
- Gram Positive Bacteria's cell wall is made of peptidoglycan which is polysaccharides (sugars) and amino acid chains together which form a rigid cell wall. These bacteria will take up a stain and turn purple.
- Gram Negative Bacteria's cell wall is made of lipopolysaccharides which is lipids (fats) and polysaccharides (sugars) together. Due to the fats, the gram negative bacteria will not soak up the stain and will turn red.
- Why is this important?
-The difference in gram negative and positive bacteria is crucial for doctors when treating an illness. The gram negative bacteria are more resistant to antibiotics because of the fats. This is important for doctors to determine in order to know how much of or what kind of antibiotic to give a patient.

Prokaryotic Metabolism
  • Photoautotrophs- photosynthetic bacteria. Using power of the sun.
  • Chemoautotrophs- oxidize inorganic compounds such as nitrogen, sulfur, and hydrogen. Do not need the sun.
  • Heterotrophs- live on plant and animal matter. They live on creatures that have made the food already. They are decomposers and pathogens.
- Mutations
Bacteria reproduce every 20 minutes by binary fission.
- They can reproduce asexually
- There is a 1 in 200 error rate in copying DNA. The high resistance to antibiotics is due to this error rate and the rapid pace at which bacteria reproduce.
- Bacteria can mix genes. They have lots of plasmids which are supplemental circles of DNA (genomic). The bacteria can send out these circles of DNA and others can pick them up thus further spreading the mutation.
-This is both advantageous and detrimental to us. Because of their quick reproduction it is easy for doctors to get the genes they want in the cells and to get them to reproduce these genes. However, it is detrimental because it spreads resistance.

- Pathogens are disease causing microbes. In Plants they cause wilting, fruit rot and blights.
In Animals they can cause tooth decay, ulcers, anthrax, botulism, STDS, plague, leprosy, Lyme disease, and pneumonia among many others.

- Bacteria are good too!
- Bacteria act as decomposers and recycle the nutrients from the dead to the living.
- Bacteria are the only organisms that can fix nitrogen from atmosphere which is essential for synthesis of proteins and nucleic acids.
- They help in digestion by digesting cellulose for herbivores.
- They produce vitamins K which clots blood and B12. This is a mutual symbiotic relationship. As the bacteria gets to eat, we are getting vitamin K.
- They can produce foods like yogurt and medicines like insulin.

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