|
|
General Characteristics
Archaebacteria
- prokaryotic
- heterotrophs
- live in salt lakes, hot springs, animal guts
PHYLUM
1. extreme halophiles - an organism that requires a salty environment
2. methanogens -
-
common name of organisms requiring completely anaerobic conditions for growth
-
produce methane gas as a catabolic product
-
they are found in the bovine stomach, swamp mud, and other environments where oxygen is not present.
-
There are four taxonomic orders: methanobacteriales, methanococcales, methanomicrobiales, and methanosarcinales
3. extreme thermophiles - organisms requiring high temperatures for normal development, as certain bacteria.
Eubacteria
- simple organisms lacking nuclei (prokaryotic)
- either heterotrophs or autotrophs
- all can reproduce asexually
- live nearly everywhere
PHYLUM
1. bacteria -
-
Any of the unicellular prokaryotic microorganisms which vary in terms of morphology, oxygen and nutritional requirements, and motility
-
They can be free-living, saprophytic, or pathogenic in plants or animals.
2. cyanobacteria -
|
|
|
Anatomical and Physiological Characteristics
- Eubacteria and Archaebacteria is mainly asexual by binary fission.
- Their abundance is largely a result of their rapid rate of reproduction.
- Eubacteria and archaebacteria display a variety of modes of nutrition
- Eubacteria take part in many ecological processes, e.g., decomposition, nitrogen fixation, and oxygen production.
- They are pathogens.
Respiration and Nutrition
- obligate aerobes - bacteria that require oxygen for respiration
- obligate anaerobes - bacteria that conduct respiration processes in the absence of oxygen
- facultative anaerobes - bacteria that prefer environments with oxygen, but can live without oxygen
- When oxygen is absent, both obligate and facultative anaerobes obtain energy from fermentation.
|
|
|
Reproduction and Growth
- Eubacteria and archaebacteria reproduce asexually by binary fission.
o The single strand of bacterial DNA replicates, resulting in identical genetic material being transferred to each new cell. o Following replication of the genetic material, the bacterium produces a cross wall and divides into two identical cells which may separate or remain attached. - Sexual reproduction is not common, but conjugation does occur among some intestinal bacteria
o In conjugation, two conjugal bacteria, referred to as donor and recipient, make cell-to-cell contact by means of a cytoplasmic bridge.
o Plasmids are transferred from the donor to the recipient to form new DNA with an altered set of characteristics.
- Some bacteria of the bacillus type have adapted to survival during unfavourable conditions by forming resting cells known as endospores.
o Endospores are genetic material encapsulated by a thick, resistant cell wall.
|
| |
|
|
|
