1. List unique characteristics that distinguish archaea from bacteria.

2. Archaea Evolved from the earliest cells Inhabit only very extreme environments Only a few hundred species exist Bacteria The “modern” prokaryotes Over 10,000 species Differ structurally, biochemically, and physiologically from Archaea  1. List unique characteristics that distinguish archaea from bacteria.

4. 2. Describe the three domain system of classification and explain how it differs from previous systems. • Domain Archaea  Archaebacteria • Domain Bacteria  Eubacteria • Domain Eukarya  all eukaryotes • “domain” is above the Kingdom taxon, and includes all taxa below 

6. 3. Using a diagram, distinguish among the three most common shapes of prokaryotes. • Spheres (cocci) • Rods (bacilli) • Helices (spirilla & spirochetes)

7. 4. Describe the structure and functions of prokaryotic cell walls. 1. Maintain cell shape 2. Protect cell 3. Prevent cell from bursting • Differ in chemical composition and construction than protists, plants and fungi • Made of peptidoglycan  modified sugar polymers crosslinked by short polypeptides (archaea don’t have it) 

11. Chapter 27 Reading Quiz • Which structure in bacteria contains “peptidoglycan”? • How do prokaryotes reproduce? • What do aerobes utilize? • Extreme halophiles like what substance? • What term describes ecological relationships between organisms of different species?

12. 5. Distinguish between the structure and staining properties of gram-positive and gram-negative bacteria. • Gram stain  a stain used to distinguish two groups of bacteria by virtue of a structural difference in their cell walls • Gram +  simple cell walls with lots of peptidoglycan - these stain blue in color • Gram -  more complex cell walls with less peptidoglycan - Outer lipopolysaccharide-containing membrane that covers the cell wall - these stain pink in color 

13. 6. Explain why disease-causing gram-negative bacterial species are generally more pathogenic than disease-causing gram-positive bacteria. • The lipopolysaccharides: - these are often toxic and the outer membrane helps protect these bacteria from host defense systems - can impede the entry of drugs into the cells, making gram negative bacteria more resistant to antibiotics 

14. 7. Describe three mechanisms motile bacteria use to move. • Flagella • Filaments  characteristic of spirochetes - spiral around cell inside cell wall and rotate like a corkscrew • Gliding  glide through a layer of slimy chemicals secreted by the organism - movement may result from flagellar motors that lack the flagellar filaments 

16. 8. Explain how prokaryotic flagella work and why they are not considered to be homologous to eukaryotic flagella. • Prokaryotic flagella are unique in structure and function • They lack the 9 + 2 microtubular structure and rotate rather than whip back and forth • They are not covered by plasma membrane • They are 1/10 the width of eukaryotic flagella 

18. 9. Indicate where photosynthesis and cellular respiration take place in prokaryotic cells. • Photosynthesis  prokaryotes have specialized metabolic machinery with internal membranes and a light-harvesting pigment system • Cellular respiration  most prokaryotes use this, including saprobes and parasites • Occurs in infoldings of the plasma membrane, like mitochondria 

20. 10. Explain how the organization of the prokaryotic genome differs from that in eukaryotic cells. • Lack diverse internal membranes of eukaryotes • Genome has 1/1000 as much DNA as eukaryotes • Has a genophore  the bacterial chromosome (one strand of circular DNA) - concentrates in the “nucleoid region” with no surrounding nuclear membrane • Has plasmids  smaller rings of DNA with supplemental genes for functions like antibiotic resistance 

22. 11. Explain what is meant by geometric growth. • One cell divides into two, two divide into four, four into eight, etc… • Essentially, growth doubles with each generation 

23. 12. List the sources of genetic variation in prokaryotes. • Transformation  the process by which external DNA is incorporated by bacterial cells • Conjugation  the direct transfer of genes from one bacterium to another • Transduction  the transfer of genes between bacteria by viruses 

24. Autotrophs  organisms that synthesize their food from inorganic molecules and compounds - Example: Plants, cyanobacteria Heterotrophs  organisms that require organic nutrients as their carbon source - Example: Animals, some bacteria  13. Distinguish between autotrophs and heterotrophs.

25. 14. Describe four modes of bacterial nutrition and give examples of each. • Photoautotrophs  use light energy to synthesize organic compounds from CO2 - examples: plants, cyanobacteria • Chemoautotrophs  require CO2 as a carbon source and obtain energy by oxidizing inorganic compounds like H2S, NH3, Fe2+ - example: Archaea, Sulfobolus • Photoheterotrophs  use light to generate ATP from an organic carbon source (unique to some prokaryotes) • Chemoheterotrophs  must obtain organic molecules for energy and as a carbon source - examples: most bacteria and most eukaryotes 

27. 15. Distinguish among obligate aerobes, facultative anaerobes and obligate anaerobes. • Obligate aerobe  prokaryotes that need O2 for cellular respiration • Facultative anaerobe  prokaryotes that use O2 when present, but in its absence can grow using fermentation • Obligate anaerobe  prokaryotes that are poisoned by oxygen and live exclusively by fermentation - they use other inorganic molecules as electron acceptors (other than O2) 

28. 16. Describe, with supporting evidence, plausible scenarios for the evolution of metabolic diversity of prokaryotes. • The 1st prokaryotes must have been anaerobes and simple • In the beginning, as ATP supplies were depleted, natural selection selected prokaryotes that could regenerate ATP from ADP, leading to glycolysis (no O2) • The 1st prokaryotes were probably chemoautotrophs (rare in today’s world) 

29. 17. Explain how molecular systematics has been used in developing a classification of prokaryotes. • By comparing energy metabolism • Ribosomal RNA comparisons show prokaryotes diverged into Archaea and Bacteria lineages early – the RNA indicates the presence of “signature sequences” = domain-specific base sequences at comparable locations in ribosomal RNA or other nucleic acids • Bottom line  they found that Archaea have at least as much in common with eukaryotes as they do with bacteria 

31. 18. List the three main groups of archaea, describe distinguishing features among the groups and give examples of each. • Methanogens  named for their unique form of energy metabolism - use H2 to reduce CO2 to CH4 (strict anaerobes) - important decomposers and digestive system symbionts with termites and herbivores • Extreme halophiles  like high salinity environments (15 – 20%) - have the pigment bacteriorhodopsin in the plasma membrane - absorb light to pump H+ ions out • Extreme thermophiles  inhabit HOT environments (60 – 80 degrees Celsius) - one sulfur-metabolizing thermophile lives in 105 ‘C water by underwater hydrothermal vents 

33. 19. List the major groups of bacteria, describe their mode of nutrition, some characteristic features and representative examples. • Spirochetes  helical chemoheterotrophs; flagella; ex: Lyme disease • Chlamydias  obligate parasites; gram – cell walls; most common STD – causes blindness • Gram positive  some are gram – but grouped here due to molecular systematics; example – Clostridium • Cyanobacteria  photoautotrophs; example – Anabaena • Proteobacteria  1. Purple bacteria: photoautotrophs; Chromatium 2. Chemoautotrophic: free-living and symbiotic; Rhizobium 3. Chemoheterotrophic: in intestinal tracts; Ecoli, Salmonella

34. 20. Explain how endospores are formed and why endospore-forming bacteria are important to the food-canning industry. • Endospore  resistant cell formed by some bacteria; contains one chromosome copy surrounded by a thick wall • Original cell replicates chromosome and surrounds one copy with a durable wall • Endospores can survive boiling water for a short time - special precautions must be taken to kill endospores of dangerous bacteria 

35. 21. Explain how the presence of E. coli in public water supplies can be used as an indicator of water quality. • E. coli is found in the intestines and excretion of animals and if found in drinking water or post-plant sewage, the sewage system is bad (leaking, etc) 

36. 22. Explain why all life on earth depends upon the metabolic diversity of prokaryotes. • Earth’s metabolic diversity is greater among the prokaryotes than all of the eukaryotes • The diversity is a result of adaptive radiation over billions of years • Examples: cyanobacteria – make oxygen saprobes – decompose dead materials 

37. 23. Distinguish among mutualism, commensalism, and parasitism. • Mutualism  symbiosis in which both symbionts benefit (+/+) • Commensalism  symbiosis in which one symbiont benefits while neither helping nor harming the other symbiont (+/0) • Parasitism  symbiosis in which one symbiont (the parasite) benefits at the expense of the host (+/-) 

39. 24. List Koch’s postulates that are used to substantiate a specific pathogen as the cause of a disease. • Find the same pathogen in each diseased individual • Isolate the pathogen from a diseased subject and grow it in a pure culture • Use cultured pathogen to induce the disease in experimental animals • Isolate the same pathogen in the diseased experimental animal 

40. Exotoxins  proteins secreted by bacterial cells - can cause disease without the organism being present - these are among the most potent poisons (example: botulism & cholera) Endotoxins  toxic component of outer membranes of some gram – bacteria - usually induces fever and aches (example: Salmonella)  25. Distinguish between exotoxins and endotoxins.

41. 26. Describe how humans exploit the metabolic diversity of prokaryotes for scientific and commercial purposes. • The range of purposes has increased through recombinant DNA technology • Cultured bacteria to make vitamins and antibiotics • Used as simple models of life to learn about metabolism and molecular biology • Methanogens digest organic waste at sewage plants • Decompose pesticides and other synthetic compounds • Make products like acetone and butanol • Convert milk into yogurts and cheeses for consumption 

42. 27. Describe how Streptomyces can be used commercially. • Many of the antibiotics that we now use are produced naturally by members of the genus Streptomyces