Chapter 21The Nature of Microorganisms

Domains

The three domains: Eubacteria Archaea Eucarya

Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia

Bacteria Differences in Eubacteria and Archaea

Eubacteria has the compound peptidoglycan in their cell wall, Archaea does not

Different kind of lipids in their plasma membrane The DNA of Archaea is largely unique from other

living organisms Eubacteria and Eukaryotes are more similar in genetic

make-up, than Eubacteria and Archaea

Eubacteria “True Bacteria”

There are 2,000 species of Eubacteria which have been named Mostly spherical, rod-shaped, or spiral shaped Many kinds of bacteria are heterotrophs that must

break down organic matter to provide themselves with energy, so they are known as decomposers

Can be aerobic or anaerobic The decomposition process is important in the

recycling of carbon, nitrogen, and phosphorus Some bacteria can be used to metabolize oil and be

used to clean up oil spills

Different Types of Eubacteria

Commensal Bacteria is bacteria that have a commensal relationship (cause no harm, but don't perform any valuable function) Most organisms are lined and covered by

populations of bacteria Escherichia coli is common in the intestinal tract of

humans

Different Types of Eubacteria Photosynthetic Bacteria carry on a form of photosynthesis

Cyanobacteria carries out a form of photosynthesis that is essentially same as plants

Cyanobacteria are thought to have been the first oxygen-releasing organisms, leading to aerobic respiration

Cyanobacteria are common in fresh and marine waters Purple and green bacteria carry on different forms of

photosynthesis which release sulfur instead of oxygen

Different Types of Eubacteria

Mutualistic Bacteria occur between bacteria and other organisms

Mutualism is an interrelationship in which two species live in close association with one another and both benefit Some intestinal bacteria produces antibiotics for

humans to inhibit disease-causing bacteria When people travel, they consume local bacteria

and have problems establishing a new symbiotic relationship with these foreign bacteria

Disease-Causing Bacteria Pathogens are organisms that cause disease

Only a small minority of bacteria fall into this category

Streptococcus pneumoniae grows in the throats of healthy people, but when their numbers increase, it can cause illness

After a viral flu, person's resistance is lowered, and can invade lungs

Goes from commensalistic to parasitic Some bacteria can invade healthy tissue of host by

releasing enzymes to break down tissue Other bacteria can produce toxins or poisons

Biological Warfare

Bacteria and other microbes can spread through a population quickly and cause disease

Biological agents can reproduce, spread through populations and cause epidemics, even after a war has ended More recent example in 2001, letters containing

anthrax where mailed from New Jersey. Five people died, and 22 were infected

Other human bacterial diseases: Botulism, plague, TB, typhoid fever

Domain Archaea

Archaea is a diverse group of organisms that generally live in extreme environments, so they are known as extremophiles Methanogens are strict anaerobes, and release

methane as a waste product Live in mud at bottom of lakes and swamps; intestinal

tracts of animals, including humans Extreme Halophiles (salt lovers) live in only extremely

acidic environments, such as the Great Salt Lake; they grow best at solutions which are 20% salt

Thermophiles (heat lovers) live in extremely hot environments; hot springs at Yellowstone National Park, hydrothermal vents on the ocean floor

Domain Eucarya

Kingdom Protista are a broad category of simple eukaryotic organisms; not necessarily closely related to one another

There are more than 100,000 species The species are divided into three general

groups Autotrophic Unicellular Organisms (Algae) Heterotrophic Unicellular Organisms (Protozoa) Funguslike Protists (Slime & Water molds)

Kingdom Protista - Algae

Algae are protists which contain chlorophyll in their chloroplasts so they undergo photosynthesis Many are single-celled, many are multicellular Live in bodies of freshwater, and other moist places Plankton is a collection of small, floating or weakly

swimming organisms Phytoplankton consists of photosynthetic plankton,

which algae is a major component

Algae Single-Celled Algae

Three common forms: Euglenids Dinoflagellates Diatoms

Euglenids are single-celled algae moved by flagella, most are found in freshwater

Dinoflagellates (two flagellas) are important food producers Some have a symbiotic relationship with coral reefs by

providing nutrients for the reef Diatoms are a major component of phytoplankton and

a major food source for filter-feeders

Algae

• Multicellular algae

• Can grow to be quite large with some specialized cells and body parts

• Commonly known as seaweed

• Red Algae live in warm oceans and attach to the ocean floor

• Brown Algae is found in cooler marine environments and can grown into over 100 m of length

• Used as jellying agent or thickener

Protozoa

• Protozoa are eukaryotic, heterotrophic, single-cell organisms that lack cell walls

• Flagellates

• Amoeboid Protozoans

• Apicomplexa

• Ciliates

Protozoa• Flagellates

• Very diverse group that have a flagella and lack cell walls and chloroplasts

• Termites have flagellated protozoa that digest the cellulose found in wood

• Amoeboid Protozoans

• Have extensions of their cell surface called pseudopods (false foot)

• Amoebas use the pseudopod for movement and to engulf food

Protozoa

• Apicomplexa

• Nonmotile parasites

• Plasmodium vivax causes malaria

• Ciliates

• Complex cellular structure and numerous short, flexible extensions from the cell called cilia

• Paramecium have 15,000 cilia per cell and move at 1 mm/ssec

Funguslike Protists

• Funguslike Protists are often confused with fungi. However, funguslike protists have cellulose in their cell wall, while fungus cell walls have chitin.

• Slime molds are amoeba-like organisms that crawl and digest dead organic matter

• Water molds• A water mold was responsible for the Irish potato blight

Kingdom Fungi

• Members of Kingdom Fungi are nonphotosynthetic, eukaryotic organisms with rigid cell walls containing chitin

• Fungus usually consists of a filaments composed of many cells, each individual filament is known as a hypha. Several hyphae form a network known as a mycelium.

Kingdom Fungi• Even though fungi are nonmotile, they are easily

dispersed through huge numbers of spores. A spore is a cell with a tough, protective cell wall that can resist extreme conditions.

• A good-sized puffball can have as many as 8 trillion spores

• Fungi are heterotrophs that secrete enzymes that digest large molecules into smaller ones.

• Can be free-living and absorb nutrients from decomposing dead organisms. Also can be parasitic that are responsible for athlete’s foot, and ringworm.

Kingdom Fungi

• Phylum Ascomycota, the ascomycetes is the largest group (75% of all fungi)

• Develop by sexual means; ascospores are formed inside a sac called an ascus

• Includes yeasts, morels and truffles

• Phylum Zygomycetes

• Includes black bread mold and makes up 1% of named fungi

Kingdom Fungi

• Basidiomycetes include mushrooms, toadstools, puff balls and shelf fungi

• Some may be used as food, while others are deadly poisons

• Form a club shaped reproductive structure called a basidium

Kingdom Fungi

• Yeasts are single-celled fungi

• Include Saccharomyces cerevisiae, bakers yeast

• Imperfect Fungi

• Seem to have lost their ability to reproduce sexually

• Penicillium

Kingdom Fungi• Mycorrhizae is the relationship between fungi

and the roots of plants

• Help absorb 10x more minerals than roots alone

• Lichens is the relationship between fungi and algae or cyanobacteria

• Cyanobacteria/algae provide food through photosynthesis

• Fungi help produce a damp environment needed for algae to