Kazeem Jr. Agboola & Samira Ali
12.1
The Prokaryotes: Archaebacteria and Eubacteria
Reproduction in Bacteria:








All bacteria reproduce asexually and divide by process of Binary Fission
Although division takes place in each individual cell, there is no exchange in genetic
material
Bacteria can divide up every 15 to 20 minutes
In addition to the chromosome, bacterium has another, smaller ring of DNA called a
Plasmid
Some bacterium take part in a type of sexual reproduction called Conjugation
During conjugation two bacteria connect to each other by long protein bridges. The
plasmid of one cell is transferred to the other cell. When the process is complete, the
bacterium that received the genetic material from the other cell now has two different
genetic make ups.
Having an altered gene structure increases the chance that a bacterium might possess a
gene combination that enables the organism to adapt to worsening environmental
conditions
Conjugation is a one-way process. One cell donates a plasmid, another receives it
The Kingdom of Archaebacteria:








Archaebacteria is considered to be the oldest group of organisms on earth.
Scientist hypothesis all life’s kingdoms originate from this group (Archaebacteria)
They are well known for their various and diverse environments which they live, often
inhospitable for other life forms
These bacteria-like organisms resemble primitive clusters of molecules thought to be
found in ancient seas
A typical acrhaebacterium has a cell wall and a cell membrane that offers further
protection to the organelles. They are much different when it comes to Eubacteria,
Eubacteria and Archaebacteria are so different they are members of different kingdoms
Archaebacteria are divided into several phyla based on their habitats. The members of
phylum live in oxygen-free places such as gut of animals and produce methane gas. They
are called anaerobic methanogens.
A second group, the halophiles, are “salt loving” organisms that inhabt salt lakes such as
the Dead Sea.
The third, group are the thermophiles, inhabit hot, acidic environments such as hot
springs
Kazeem Jr. Agboola & Samira Ali
Kingdom of Eubacteria



This kingdom is more successful than Archaebacteria, accounting for most of the
prokaryote on earth.
Six phylogenetic groups: Spirochetes, Chlamydias, gram-positive bacteria,
Cyanobacteria, and proteobacteria.
Each group contains a wide variety of species with different nutritional patters, gas
exchange mechanisms.
Bacteria in ecosystems
Nitrogen Fixation
 Ecosystems are communities of organisms living together in a given area
 The survival of organisms living in the ecosystems depends on, in part, on the availability
of nitrogen
 Nitrogen makes up 78% of the earth’s atmospheres
 Nitrogen must be converted to or “fixed” into a useful form
 The greatest amount of nitrogen fixation s caused by nitrogen-fixing bacteria that are
either free living in the soil or inhabitant the roots of legumes, such as alfalfa, soybeans,
peas, and clover.
 A common symbiotic nitrogen fixer Rhizobium.
 Animals that feed on plant proteins and metabolize them to obtain nitrogen and amino
acids
Carbon & Oxygen cycle
o -Prokaryotes play an important role in recycling.
o -these bacteria break down organic matter into forms suitable for growth and
reproduction. The bacteria release carbon dioxide back into the atmosphere
o Bacteria and disease
o -Bacteria affects humans in a variety of ways, some cause disease.
- only a small percent of prokaryotes are pathogenic/ disease causing
o -ex. the plague
Putting bacteria to work
Waste management

Canada has over 5000 hazardous waste sites that contain things like, battery acid,
used oil, detergents etc. which are neutralized by bacteria to eliminate the toxins and
even to clean up spills
Kazeem Jr. Agboola & Samira Ali
Dairy foods



Over the last 30 years, efforts by food scientist to identify and investigate lactic acids
bacteria, Bacterium lactis, have revealed many uses
These uses include acid production, texture development, flavour generation,
preservation, and synthesis of B-vitamins.
Genetically engineered lactic acid bacteria are now being studied to develop highly
effective digestive enzymes and vaccines