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Kingdom Eubacteria
Kingdom Archaebacteria
Different types of bacteria…
Bacteria cells are usually one of three different shapes:
Rods (bacillus)
Spheres (coccus)
Spirals (spirillum)
Bacteria can be arranged in several ways:
When bacteria are found in colonial arrangements, we name them based on their arrangement and their shape.
The first part of the name represents the arrangement. The second part represents the shape.
2 cells: diplo
A strand of cells: strepto
A cluster of cells: staphylo
Examples
Two rod­shaped cells
Diplobacillus
Spherical cells in a linear strand
Bacterial Cell Structures:
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Nucleoid Plasmid
Ribosomes
Plasma Membrane
Cell Wall
Flagella
Pili
Bacterial DNA is not contained in a nucleus (remember….no membrane­bound organelles!)
Streptococcus
Instead, the DNA is tangled up in an area we call the nucleoid.
Bacterial DNA forms loops known as plasmids.
Bacteria cells are classified based on how they react to a certain chemical stain developed by Dr. Gram
Gram­positive:
They retain a purple color when stained with crystal violet.
Bacteria may achieve motility in three ways:
­Using flagella (whiplike structure)
­An axial filament (bacteria cell moves like a corkscrew)
­Secretes slime to glide through
Other bacteria cells have no cell wall and react differently to the Gram stain
These bacteria are known as Gram negative because they do not stain purple.
How they stain determines what antibiotic is perscribed. How do bacteria cells reproduce?
1. Binary Fission
Bacteria doubles its size, replicates its DNA and divides.
Each daughter cell is identical to the parent cell.
2. Bacterial Conjugation
The connection that is formed between two bacteria cells is known as the conjugation bridge.
The structure that forms the conjugation bridge is called a pili.
Genes move from one cell to the other, increasing genetic diversity.
http://www.learner.org/courses/biology/archive/animations/hires/a_infect1_h.html
3. Spore Formation
Bacteria can form endospores when growth conditions become unfavourable. Theses spores can remain dormant for months or even years while waiting for more favourable conditions. Makes bacteria able to survive harsh conditions.
Ex: Anthrax
Good Bacteria vs. Bad Bacteria There are many bad bacteria in our environment that can do harm to our bodies.
These bacteria cells are known as pathogenic bacteria
Bacteria cells can be easily manipulated and help us produce a variety of products.
For example, we can use bacteria cells to help us produce insulin!
Insulin Production in Bacteria
Genetic Recombination
• The gene responsible for insulin production in humans is removed.
• The plasmid in the bacteria cell is opened.
• The human gene is inserted into the plasmid.
• The bacteria cell reads the new gene along with it’s own DNA and becomes an insulin­producing factory! • Insulin is removed from the bacteria cells and given to individuals with diabetes!
Bacteria and Food Production
Bacteria are used in the production of foods such as:
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Chocolate
Sausage
Dill Pickles
Soy Sauce
Olives
Dairy Products (Milk, Cheese, Yogurt)
Bacteria and Vitamins
• Vitamin B12 is synthesized exclusively by bacteria through a process called fermentation.
• Vitamin B12 is necessary for the synthesis of red blood cells, the maintenance of the nervous system, and growth and development in children. http://www.youtube.com/watch?v=kecBi27dhjw&feature=related
Bacillus anthracis (Anthrax)
Commonly occurs in ruminants
Cattle, sheep, goats, etc.
Humans who are exposed to infected animals or a high density of spores (endospore) will become infected.
There are no known cases of people catching anthrax from one another.
Anthrax continued…
Anthrax can infect three different areas:
• Gastrointestinal Anthrax (intestine)
• Pulmonary Anthrax (lungs)
• Cutaneous Anthrax (Least fatal; least painful)
Escherichia Coli
Streptococcus pharyngitis
• These bacteria attack the pharynx.
E. Coli live in the lower intestine of many animals (including us). They produce many vitamins that the body cannot produce itself.
However, they can cause several infections when they appear in an area of the body that they are not normally found.
Ex. Urinary Tract Infections
Sometimes E. Coli produce a toxin that attacks the body and makes us ill.
Ex. Food Poisoning
Antibiotics
Bacterial infections can be treated with antibiotics
Ex: penicillin
Antibiotics are compounds that block the growth and reproduction of bacteria.
One of the major reasons for the dramatic increase in life expectancy over the past two centuries.
These bacteria are spread through direct contact
(water droplets
from sneezing and
coughing)