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

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

3. 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.

4. 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 (-)

5. Bacterial cells structure

6. Shapes of bacteria

7. 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

8. Decomposers in sewage

9. 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

10. 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

11. Cyanobacteria Photosynthetic eubacteria
Cyanobacteria performs photosynthesis like plants.
Chlorella
Spirulina

12. Cyanobacteria

13. 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.

14. 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

15. A bacterial plant disease

16. 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

17. 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

18. Relationships among members of the protista

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

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

21. 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.

22. 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

23. 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

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

25. Single-celled algae

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

27. Red and brown algae

28. 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

29. Green algae

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

31. 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.

32. Flagellates

33. 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

34. Ameboid protozoa

35. 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

36. Ciliates

37. 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.

38. The life cycle of Plasmodium vivax

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

40. 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

41. The development of multicellular green algae

42. 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

43. Mycelium

44. Fungus taxonomy

45. 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.

46. 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

47. Mycorrhizae

48. 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

49. Lichens

50. 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

51. Corn smut

52. 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

53. Poisonous mushrooms