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- Single cell (unicellular) organism.
- Genetic material (DNA) is not enclosed in a specific nuclear membrane.
- Bacterial cells are called Prokaryotes; prokaryotes included bacteria and archaea.
- Shape - Bacillus, Coccus, spiral
- Arrangement - pairs, chains, cluster; such formation are usually characteristic of a particular genes or species of bacteria.
- Enclosed in cell walls that are largely composed of carbohydrate and protein complex called peptidoglycan.
- Bacteria generally reproduce by dividing into two equal cells; this process is called binary fission.
- For nutrition, most bacteria use organic chemicals, which in nature can be derived form either dead or living organisms.
- Some bacteria can manufacture their own food by photosynthesis, and some can drives nutrition from inorganic substances.
- Many bacterium can "swim" by using moving appendages called flagella
- Archaea consist of prokaryotic cells
- If they have cell walls, the walls lack peptidoglycan
- Found extreme environments such as hot springs and dead sea
- Archaea are not known to cause disease in humans
Three types of Archaea which found extreme environments.
- Methenogens - produce methane as a waste products form respiration
- Extreme halophiles - (halo - salt, philes - loving) live in extreme salty environments such as the great salt lake and dead sea
- Extreme thermohiles - (Thermo -heat) live in hot sulfurous water, such as hot springs at Yellowstone National Park
- Distinct nucleus containing the cell's genetic material (DNA), surrounded by a special enveloped called nuclear
- Kingdom fungi may be unicellular or multicellular
- Large multicellular fungi - mushroom
- Fungi cannot carry out photosynthesis
- True fungi have cell walls composed primarily of a substance called chitin
- Unicellular form of fungi - yeast are oval microorganisms that are larger than bacteria
- Most typical fungi - mold
- Mold forms visible masses called mycelia, which are composed of long filaments (hyphae) that branch and intertwine
- Reproduce sexually or asexually
- They obtain nourishment by absorbing solutions of organic materials form their environments - soil, seawater, freshwater, animal or plant host
- Organisms called slime molds have characteristic of both fungi and amoebae
- Unicellular eukaryotic microbes
- Protozoa move by Pseudopods, flagella, cilia
- Amoebae move by using extensions of their cytoplasm calls Pseudopods
- Other protozoa have flagella or numerous shorter appendages for locomotion cilia
- Protozoa have a variety of shapes and live either as free entities or as parasites (organism that derives nutrients form living host) that absorb or ingest organic compounds
- Some protozoa, such as Euglena are photosynthetic. they use light as a source of energy and carbon dioxide as their chief source of carbon to produce sugars
- Reproduce sexually or asexually
- Photosynthetic eukaryotes with a wide variety of shapes and both sexual and asexual reproductive forms
- Cell walls of many algae are composed of carbohydrate called cellulose
- Photosynthesizer, algae need light, water, and carbon dioxide or food production and growth, but they do not generally require organic components from environments
- As a result of photosynthesis, algae produce oxygen and carbohydrate that are then utilized by other organisms including animals
- Algae play an important role in the balance of nature
- Can be seen only with an electron microscope and they are acellular (not cellular)
- Virus particles contains a core made of only one type of nucleic acid ether DNA or RNA
- Virus core is surrounded by a protein coat, which is sometimes encapsulated by a lipid membrane called an envelope
- Virus can reproduce only by using cellar machinery of other organisms
- Viruses are considered to be living only when they multiply within host cells they infect, however, viruses are parasites of other form of life. Viruses are not considered to be living because they are inert outside living host.
Multicellular Animal Parasites
- Not strictly microorganisms
- Animal parasites are eukaryotes
- The two major groups of parasitic worms are the flatworms and roundworms collectively called helminths
- During same stages of their life cycle, helminths are microscopic in size
Some forms of life could arise spontaneously from nonliving matter
Hypothesizing that living cells arise only from preexisting living cells
- Pasteur demonstrated the microorganisms are present in the air and can contaminate sterile solutions, but the air itself does not create microbes
- Pasteur demonstrated that microbes are responsible for food spoilage, leading researchers tot he connection between microbes and disease
- His experiment and observation provided that basis of aseptic techniques, which are used to prevent microbial contamination
procedures that prevent contamination by unwanted microorganisms, which are now the standard practice in laboratory and many medical proceures
- the first proof that bacteria actually cause disease came form Robert Koch
- Koch discovered the cause of Anthrax, a disease that was destroying cattle and sheep in Europe
- Koch discovered rod shaped bacteria now known as Baillus antrasis in blood of cattle died of antrax. He cultured the bacteria on nutrients and then injected samples of the culture into healthy animal. when these animal became sick and died, Koch isolated the batterer in their blood and compared them with the originally isolated bacteria. He found that the two set of blood cultures contained the same bacteria
- Koch's Postulates, a sequence of experimental steps for directly relating a specific microbe to a specific disease