PowerPoint to accompany CONCEPTS IN BIOLOGY Enger • Ross • Bailey CHAPTER 21

What are microorganisms? A tiny organism that cannot be seen without a microscope. Live in a variety of different habitats

Domains eubacteria and archaea Used to be lumped into one group, bacteria Eubacteria have cell walls with peptidoglycan. Archaea and eubacteria have chemically unique cell membranes. So different from each other necessary to classify into different Domains of life.

Domain eubacteria Identified by Their shape Metabolic reactions Can be rods, spheres or spiral-shaped Metabolic reactions Chemistry of their cell walls Gram (+) and Gram (-)

Bacterial cells structure

Shapes of bacteria

Domain eubacteria Occupy many different ecological niches Decomposers Heterotrophs that break down organic matter Called saprophytes Can live on dead organic matter Some are anaerobic. – tetanus, botulism Others are aerobic and break down organic matter into carbon dioxide and water. Important in recycling carbon, nitrogen, phosphorus, etc. Could be used to break down sewage, clean up oil spills Used in food production (blue cheese, yogurt, beer, wine, etc.) Are responsible for food spoilage

Decomposers in sewage

Domain eubacteria Commensal bacteria +/ø Mutualistic +/+ Bacteria that live on or in organisms without benefiting or harming the host Mutualistic +/+ Normal microflora- Bacteria on our skin E. coli in our large intestine

Domain eubacteria Mutualistic bacteria E. coli in our large intestine Produce antibiotics and compete for resources Reducing the growth of pathogenic bacteria They produce and release vitamin K. Cyanobacteria and fungi in lichens Plants and nitrogen-fixing bacteria in their roots

Cyanobacteria Photosynthetic eubacteria Cyanobacteria performs photosynthesis like plants. Chlorella Spirulina

Cyanobacteria

Domain eubacteria Bacteria and mineral cycles Nitrogen cycle Nitrogen-fixing bacteria transform atmospheric nitrogen into ammonia. Ammonia can be used by plants to make amino acids. Other bacteria convert ammonia waste to nitrate or nitrite. Other bacteria convert nitrite to atmospheric nitrogen.

Domain eubacteria Disease-causing bacteria Also called pathogens or parasites +/- Some commensalistic bacteria can become pathogenic. If they are given the opportunity to increase in number If they have the opportunity to invade new tissue Example: S. pneumoniae

A bacterial plant disease

Domain eubacteria Control of bacterial populations Bacterial populations grow rapidly because Their generation time is so short. About every 20 minutes 1 bacteria can lead to millions in a matter of days They can generate resistant forms or stages. Spores They mutate rapidly. Can produce antibiotic resistant strains MRSA, VRE

Kingdom protista A catch-all kingdom Divided into three groups Includes a diverse array of organisms Many are not evolutionarily related to one another. All are eukaryotic Most are single celled; some are multicellular. Divided into three groups Algae Autotrophic, unicellular Protozoa Heterotrophic, unicellular Fungus-like protists

Relationships among members of the protista

Algae Contain chlorophyll and can carry out photosynthesis Most are aquatic. Plankton float in the water. Phytoplankton are photosynthetic. Zooplankton are heterotrophic.

Algae The terrestrial forms live in very moist areas. Most are unicellular; a few are multicellular.

Single-celled algae Euglenids Move by flagella Have a flexible outer covering called a pellicle Gives them a shape Some are heterotrophs, others are autotrophs. Many live in freshwater.

Single-celled algae Diatoms Found in freshwater, marine and soil environments Major component of phytoplankton A few are heterotrophs. Brownish in color Do not have cilia or flagella Have cell walls made of silica Diatomeous earth

Single-cell algae Dinoflagellates Important primary producers in marine ecosystems Also occur in freshwater Have two flagella Have outer covering made of cellulose Most are autotrophs. Some are heterotrophs. Some are parasitic. Red tides

Single-cell algae Some produce toxins that can kill fish. Red tide Can poison humans if they eat poisoned fish Some are bioluminescent.

Single-celled algae

Multicellular algae Commonly known as seaweed. Red algae Live in warm oceans Used to produce agar and carrageenin

Red and brown algae

Multicellular algae Brown algae Green algae Live in cooler marine environments Can grow very long Produce alginates (food stabilizer) Green algae Found in freshwater ecosystems Are photosynthetic and have cellulose cell walls

Green algae

Protozoa Eukaryotic Heterotrophic Unicellular Lack cell walls Classified by their means of locomotion Flagellates Ameboid Ciliates Apicomplexa

Flagellates Have flagella Live in moist environments Many are mutualistic. Found in termite gut; digest cellulose Many are parasitic . Trichomonas vaginalis-common sexually transmitted disease Trypanosomes cause sleeping sickness in humans and cows. Giardia causes intestinal distress, diarrhea, gas.

Flagellates

Amoeboid protozoans Move via pseudopods Cellular extensions in which cytoplasm flows Most are free-living. Feed on algae, bacteria, etc. Some are parasitic. Amoebic dysentery Examples Amoeba

Ameboid protozoa

Ciliates Contain cilia Ruminants have ciliates in their gut. Termites Beat in an organized, rhythmic fashion to move the cell Ruminants have ciliates in their gut. Termites

Ciliates

The apicomplexans Nonmotile parasites Have a spore-like stage in their life cycle Malaria is caused by an apicomplexan. Transmitted by mosquitoes to humans Reproduces in the mosquito Eliminating mosquitoes helps reduce the incidence of malaria.

The life cycle of Plasmodium vivax

Funguslike protists Have a motile reproductive stage Slime molds Move like amoeba Digest dead organic matter

Multicellularity in the protista Volvox Volvox is colonial. The flagella of each cell moves together to move the colony. Some of the cells are specialized to produce sperm and egg. Thought to be the ancestor of multicellular organisms

The development of multicellular green algae

Kingdom Fungi Nonphotosynthetic; heterotrophic Eukaryotic Secrete enzymes that digest large molecules externally Eukaryotic Have chitin-containing cell walls Made up of filaments known as hypha Hyphae form networks called mycelium Disperse through spores Cells with tough protective coating Can be produced by sexual or asexual reproduction

Mycelium

Fungus taxonomy

The significance of fungi Fungi play many roles in ecosystems Decomposers Fungi and bacteria are the major composers in ecosystems. Recycles nitrogen, carbon and phosphorus Can destroy clothes, wood, leather, food Food Fungi and their products can be used as food. Mushrooms Soy sauce is made by fermenting an ascomycete. Citric acid in cola is released from a mold. Yeasts are used to make alcoholic beverages and bread.

The significance of fungi Mycorrhizae Associations between fungi and the roots of plants One type penetrates the roots of the plant. The other type surrounds the roots but doesn’t penetrate. Found in 80-90% of all plants Increases the root’s surface area for absorption of nutrients up to 10-fold

Mycorrhizae

Significance of fungi Lichens Symbiotic relationship between a fungus and either an alga or cyanobacterium. The alga or cyanobacterium is photosynthetic and provides food. The fungus provides a moist environment. Do not require soil for growth Grow on trees or rocks Important in soil formation during ecological succession

Lichens

Significance of fungi Pathogenic fungi Can infect plants Caused the extinction of Chesnut trees and Dutch elm trees Causes wheat rust and corn smut Causes costly damage to crops Farmers have to use fungicides. Can infect humans Pneumocystis is present in most people’s lungs. Can cause infection in people with compromised immune systems

Corn smut

Significance of fungi Toxic fungi Some fungi can produce mycotoxins The mushroom, Amanita spp, makes a toxin that is deadly. “Death Angel” Food contaminated with these spores can cause illness and death. The mushroom, Psilocybe contains a hallucinogenic chemical called psilobycin. Claviceps purpurea is a parasite on rye that generates a toxin that causes hallucinations, insanity, muscle spasms and death. Witches

Poisonous mushrooms