Unicellular Organisms with no nucleus/genetic material;
Bacteria and Archaea
Bacteria: Characteristics and Features
-Relatively simple, unicellular organisms.
-Enclosed in cell walls that're mostly composed of Peptidoglycans. (in contrast, cellulose is the main substance of plant and algal cell walls)
- Reproduce = by dividing into 2 equal cells via binary fission.- Nutrition = use organic chems, in nature can be derived from either dead or living organisms, some bacteria can manufacture own food via photosynthesis.
-Movement = "swim" by moving appendages (flagella)
1.) Bacillus (rodelike)
2.) Coccus (spherical or ovoid)
3.) Spiral (corkscrew or curved)
Archaea: Characteristics and Features
-Like bacteria, consist of prokaryotic cells.
-If they have cell walls, the walls lack peptidoglycan.
-Often found in extreme environments.
-Not known to cause disease in humans.
3 Main Archaea Groups
1.) Methanogens - produce methane as a waste product from respiration.
2.) Extreme Halophiles(Halo=salt, Philic=loving)- live in extremely salty environments such as the Dead Sea
3.) Extreme Thermophiles - live in hot sulfurous water, such as hot springs in Yellowstone Park.
Fungi: Characteristics and Features
-Eukaryotes; organisms whose cells have a distinct nucleus, surrounded by nuclear membrane.
-May be unicellular or multicellular
-Large Multicellular (ie Mushrooms) - may look somewhat like plants but they cannot carry out photosynthesis.-True fungi have cell walls composed of chitin.
-yeasts; oval microorganisms
-larger than bacteria
-most typical fungi are molds.
-Form visible masses called mycelia, which are composed of long filaments (hyphae) that branch and intertwine.
-Cottony growths on bread and fruit are mold mycelia.
-Reproduce=sexually or asexually.
-Nourishment=absorbing solutions of organic material from their environment--whether soil, seawater, fresh water, or an animal or plant host)
-Slime Molds have characteristics of both fungi and amoebas.
Protozoa: Characteristics and Features
-unicellular eukaryotic microbes.
-move by pseudopods, flagella, or cilia.
-Amoebas move by using extension of their cytoplasm called pseudopods (false feet).
-Variety of shapes and live either as free entities or as parasites (organisms that derive nutrients from a living host) that absorb or ingest organinc compounds from their environment.
-Reproduce=sexually or asexually.
Algae: Characteristics and Features
-photosynthetic eukarotes with a wide variet of shapes and both sexual and a sexual reporductive forms.
-unicellular most interesting to microbiologists.
-Cell walls of many algae=cellulose (carbohydrate)
-Abundant in fresh and salt water, in soil, and in association with plants.
-Need light, water, and CO2 for food production and growth.
-Generally don't require organic compounds from the environment.
-Result of photosynthesis, algae produce O2 and carbohydrates that are utilized by other organisms.
-Thus play important role in balance of nature.
Viruses: Characteristics and Features
-very different from the other microbial groups mentioned.
-So small that they can only be seen w/ electron microscope.
-Structurally very simple, a virus particle contains a core made of only on type of nucleic acid, either DNA or RNA.
-This core is surrounded by a protein coat.
-Sometimes the coat is encased by a lipid membrane (envelope)
-Can only reproduce by using cellular machinery of other organisms.
-Only considerd living when they multiply within host
Two Major Groups of Multicellular Animal Parasites
-Collectively called helminths.
-During some stages of their life cycle, microscopic in size.
Classification of Microorganisms
-In 1978, Carl Woese devised a system of classification based on the cellular organization of organisms.
-It groups all organisms into 3 domains:
1.)Bacteria (cell walls contain a protein-carbohydrate complex called peptidoglycan.)
2.)Archaea (cell walls, if present, lack peptidoglycan.
-Protists (slime molds, protozoa, and algae)
-Fungi (unicellular yeasts, multicellular molds, and mushrooms.)
-Plants (includes mosses, ferns, conifers, and flowering plants.)
-Animals (includes sponges, worms, insects, and vertebrates.