PowerPoint to accompany CONCEPTS IN BIOLOGY

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 eubacteriahave chemically unique cell membranes. So different from each other necessary to classify into different Domains of life.

4. Domain eubacteria • Identified by • Their shape • 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 • Commensalbacteria +/ø • 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 • 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 • 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 . • Trichomonasvaginalis-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 • 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 • 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