Prokaryotes: Archaea and Bacteria

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2. Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep

3. Chapter 23 Bacteria Table of Contents Section 1 Prokaryotes Section 2 Biology of Prokaryotes Section 3 Bacteria and Humans

4. Section 1 Prokaryotes Chapter 23 Objectives • Explainthe phylogenetic relationships between the domains Archaea, Bacteria, and Eukarya. • Identifythree habitats of archaea. • Describethe common methods used to identify bacteria. • Identifyfive groups of bacteria. • Explainthe importance of nitrogen-fixing bacteria for many of Earth’s ecosystem.

5. Section 1 Prokaryotes Chapter 23 Two Major Domains: Archaea and Bacteria • Prokaryotesare single-celled organisms that do not have a membrane-bound nucleus, and can live in nearly every environment on Earth. • Although tiny, prokaryotes differ greatly in their genetic traits, their modes of nutrition, and their habitats. • Based on genetic differences, prokaryotes are grouped in two domains: Domain Archaea and Domain Bacteria.

6. Section 1 Prokaryotes Chapter 23 Three Domains of Living Organisms

7. Section 1 Prokaryotes Chapter 23 Domain Archaea • One of the ways in which archaea differ is the make up of their cell wall. Archaeal cells walls do not contain peptidoglycan. • Peptidoglycanis a protein-carbohydrate complex found in bacterial cell walls that make their cells walls rigid. • Archaea differ in the types of lipids in their cell membrane. Also, archaeal genes do contain introns.

8. Section 1 Prokaryotes Chapter 23 Domain Archaea, continued • Archaeal Groups… • …include methanogens, halophiles, and thermoacidophiles. • Methanogens convert hydrogen gas and carbon dioxide into methane. They can be found in the intestines of organisms such as cattle and termites • Responsible for “swamp gas” and methane belched by cows • Live only in anaerobic environment (no oxygen).

9. Section 1 Prokaryotes Chapter 23 Domain Archaea, continued • Archaeal Groups,continued • Halophiles are “salt-loving” archaea that live in very salty environments such as the Great Salt Lake and the Dead Sea. • Thermoacidophiles live in very hot, acidic environments, such as the hot springs of Yellowstone National Park. Some live at temperatures up to 110°C (230°F) and at a pH of less than 2. • The base of food webs in many communities

10. Section 1 Prokaryotes Chapter 23 Domain Bacteria • Bacteria occur in many shapes and sizes. Most bacteria have one of three basic shapes: rod-shaped, sphere-shaped, or spiral-shaped. • Rod-shaped bacteria are called bacilli (singular, bacillus). An example of bacilli is Escherichia coli. • Sphere-shaped bacteria are called cocci (singular, coccus). An example of cocci is Micrococcus luteus.

11. Section 1 Prokaryotes Chapter 23 Domain Bacteria, continued • Spiral shaped bacteria are called spirilla (singular, spirillum). An example of spirilla bacteria includes Spirillum volutans. • Cocci that form chains similar to a string of beads are called streptococci. • Cocci that form clusters similar to a bunch of grapes are called staphylococci.

12. Section 1 Prokaryotes Chapter 23 Three Bacterial Cell Shapes

13. Section 1 Prokaryotes Chapter 23 Characteristics of Bacteria Click below to watch the Visual Concept. Visual Concept

14. Section 1 Prokaryotes Chapter 23 Domain Bacteria, continued • Gram Stain • Most species of bacteria are classified into two categories based on the structure of their cell walls as determined by a technique called the Gram stain. • Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, and they appear purple under a microscope after the Gram-staining procedure. • Gram-negative bacteria have a thin layer of peptidoglycan in their cell wall, and they appear reddish-pink under a microscope after the Gram-staining procedure.

15. Section 1 Prokaryotes Chapter 23 Gram Staining

16. Section 1 Prokaryotes Chapter 23 Gram Stain Click below to watch the Visual Concept. Visual Concept

17. Section 1 Prokaryotes Chapter 23 Important Bacterial Groups • Bacteria are also classified by their biochemical properties and evolutionary relationships. • Proteobacteria • Proteobacteria are one of the largest and most diverse groups of bacteria, many live symbiotically with other organisms and contain several subgroups that are extremely diverse. • Members of this group include bacteria of the genus Rhizobium, the genus Agrobacterium, and the bacterium Escherichia coli.

18. Section 1 Prokaryotes Chapter 23 Important Bacterial Groups, continued • Gram-Positive Bacteria • Not all of the bacteria in this group are Gram-positive. Biologists place a few species of Gram-negative bacteria in this group because these species are genetically similar to Gram-positive bacteria. • Members of this group include the streptococcal species, Clostridium botulinum, Bacillus anthracis, and members of the genus Mycobacteria.

19. Section 1 Prokaryotes Chapter 23 Important Bacterial Groups, continued • Gram-Positive Bacteria,continued • Actinomycetes are Gram-positive bacteria, some species of which produce antibiotics. • Antibiotics are chemicals that inhibit the growth of or kill other microorganisms. Streptomycin and tetracycline are examples of antibiotics that are used medicinally.

20. Section 1 Prokaryotes Chapter 23 Important Bacterial Groups, continued • Cyanobacteria • Cyanobacteria use photosynthesis to get energy from sunlight, and make carbohydrates from water and carbon dioxide. During this process, they create oxygen as a waste product. • Once called blue-green algae, cyanobacteria are now known to be bacteria because they lack a membrane-bound nucleus and chloroplasts.

21. Section 1 Prokaryotes Chapter 23 Important Bacterial Groups, continued • Spirochetes • Spirochetes are Gram-negative, spiral-shaped bacteria that move by means of a corkscrew-like rotation. Some are aerobic. • Spirochetes can live freely or as pathogens. Pathogenic spirochetes include Treponema pallidum, the causative agent of syphilis, and Borrelia burgdorferi, which causes Lyme disease.

22. Section 1 Prokaryotes Chapter 23 Important Bacterial Groups, continued • Chlamydia • Gram-negative coccoid pathogens of the group Chlamydia live only inside animal cells. The cell walls of chlamydia do not have peptidoglycan. Chlamydia trachomatis causes the sexually transmitted infection called chlamydia.

23. Section 2 Biology of Prokaryotes Chapter 23 Objectives • Describethe internal and external structure of prokaryotic cells. • Identifythe need for endospores. • Comparefour ways in which prokaryotes get energy and carbon. • Identifythe different types of environments in which prokaryotes can live. • Listthree types of genetic recombination that prokaryotes use.

24. Section 2 Biology of Prokaryotes Chapter 23 Structure and Function • The major structures of a prokaryotic cell include a cell wall, a cell membrane, cytoplasm, ribosomes, and sometimes a capsule, pili, endospores, and flagella. (diagram & table 23-1 p.468) • Cell Wall • Most prokaryotes have a cell wall. Bacterial cell walls contain peptidoglycan. Archaeal cell walls do not have peptidoglycan; instead, some contain pseudomurein, a compound made of unusual lipids and amino acids.

25. Section 2 Biology of Prokaryotes Chapter 23 Structure and Function, continued • Cell Membrane and Cytoplasm • Bacterial and archaeal cell membranes are lipid bilayers that have proteins. However, the lipids and proteins of archaeal cell walls differ from those of bacterial cell walls. • The cytoplasm is a semifluid solution that contains ribosomes, DNA, small organic and inorganic molecules, and ions.

26. Section 2 Biology of Prokaryotes Chapter 23 Structure and Function, continued • DNA • Prokaryotic DNA is a single closed loop of double-stranded DNA attached at one point to the cell membrane. • Along with a single main chromosome, some prokaryotes have plasmids, which are small, circular, self-replicating loops of double-stranded DNA.

27. Section 2 Biology of Prokaryotes Chapter 23 Structure and Function, continued • Capsules and Pili • Many bacteria have an outer covering of polysaccharides called acapsule thatprotects the cell against drying, pathogens, or harsh chemicals. • Piliare short, hairlike protein structures on the surface of some bacteria that help bacteria connect to each other and to surfaces, such as those of a host cell.

28. Section 2 Biology of Prokaryotes Chapter 23 Bacterial Capsule Click below to watch the Visual Concept. Visual Concept

29. Section 2 Biology of Prokaryotes Chapter 23 Pilus Click below to watch the Visual Concept. Visual Concept

30. Section 2 Biology of Prokaryotes Chapter 23 Structure and Function, continued • Endospores • Some Gram-positive bacteria can form a thick-coated, resistant structure called anendosporewhen environmental conditions become harsh.

31. Section 2 Biology of Prokaryotes Chapter 23 Structure and Function, continued • Prokaryotic Movement • Many prokaryotes have long flagella that allow the prokaryotes to move toward food sources or away from danger.

32. Section 2 Biology of Prokaryotes Chapter 23 Structural Characteristics of a Bacterial Cell

33. Section 2 Biology of Prokaryotes Chapter 23 Parts of a Prokaryotic Cell Click below to watch the Visual Concept. Visual Concept

34. Section 2 Biology of Prokaryotes Chapter 23 Nutrition and Metabolism • Prokaryotes obtain nutrients either from the nonliving environment or by utilizing the products or bodies of living organisms. • Heterotrophs obtain carbon from other organisms. • Autotrophs obtain their carbon from CO2. • Phototrophs: get energy from light • Chemotrophs get energy from chemicals in the environment.

35. Section 2 Biology of Prokaryotes Chapter 23 Prokaryotic Habitats • Various prokaryotic species live in different environments. • Temperature requirements range from 0°C to 110°C. • Most prokaryotic species grow best at a neutral pH. • Obligate anaerobes: cannot live where oxygen is present • Facultative anaerobes: can live with or without oxygen • Obligate aerobes: need oxygen (ex. TB)

36. Section 2 Biology of Prokaryotes Chapter 23 Reproduction and Recombination • Binary fission – copy DNA & divide into two cells • Genetic recombination in bacteria can occur by the following three ways: • transformation(taking in DNA from the outside environment) • conjugation(exchanging DNA with other bacteria via pilli) • transduction(transmission of bacterial DNA via viruses).

37. Section 3 Bacteria and Humans Chapter 23 Objectives • Describethe ways in which bacteria can cause disease in humans. • Explainhow a bacterial population can develop resistance to antibiotics. • Identifyreasons for recent increases in the numbers of certain bacterial infectious diseases. • Identifyways of preventing a foodborne illness at home. • Listfour industrial uses of bacteria.

38. Section 3 Bacteria and Humans Chapter 23 Bacteria and Health • Human diseases may result from endotoxins or exotoxins produced by bacteria or from the destruction of body tissues. • Toxins: poisons created by bacteria that cause disease • exotoxins: poisons secreted into the environment by bacteria (ex. tetanus) • endotoxins: poisons released once the cell dies (ex. E.coli)

39. Section 3 Bacteria and Humans Chapter 23 Bacteria and Health, continued • Antibiotics and Antibiotic Resistance • A mutation in the DNA of a single bacterium can confer resistance to an antibiotic. • Cells with the mutant gene have a selective advantage when the antibiotic is present. • Mutant cells take over the population when the normal cells die.

40. Section 3 Bacteria and Humans Chapter 23 Bacteria and Health, continued • Emerging Infectious Diseases Caused by Bacteria • The number of certain bacterial diseases has increased because of the increase in the number of antibiotic resistant bacteria, the movement of people into previously untouched areas, and global travel.

41. Section 3 Bacteria and Humans Chapter 23 Bacteria and Health, continued • Food Hygiene and Bacteria • Foodborne illnesses can be avoided by selecting, storing, cooking, and handling food properly. • Frequent hand washing in hot, soapy water is also very important.

42. Section 3 Bacteria and Humans Chapter 23 Important Bacterial Diseases

43. Section 3 Bacteria and Humans Chapter 23 Bacteria in Industry • Many species of bacteria are used to produce and process different foods, to produce industrial chemicals, to mine for minerals, to produce insecticides, and to clean up chemical and oil spills. • Biologists have learned to harness bacteria to recycle compounds in a process calledbioremediation, which uses bacteria to break down pollutants.

44. Section 3 Bacteria and Humans Chapter 23 Bacteria and Food Click below to watch the Visual Concept. Visual Concept

45. Chapter 23 Standardized Test Prep Multiple Choice 1. How do bacteria produce yogurt from milk? A. by conjugation B. by fermentation C. by nitrogen fixation D. by aerobic respiration

46. Chapter 23 Standardized Test Prep Multiple Choice, continued 1. How do bacteria produce yogurt from milk? A. by conjugation B. by fermentation C. by nitrogen fixation D. by aerobic respiration

47. Chapter 23 Standardized Test Prep Multiple Choice, continued 2. What are rod-shaped bacteria called? F. cocci G. bacilli H. spirilla J. halophiles

48. Chapter 23 Standardized Test Prep Multiple Choice, continued 2. What are rod-shaped bacteria called? F. cocci G. bacilli H. spirilla J. halophiles

49. Chapter 23 Standardized Test Prep Multiple Choice, continued 3. What are thermoacidophiles? A. bacteria B. archaea C. spirochetes D. cyanobacteria

50. Chapter 23 Standardized Test Prep Multiple Choice, continued 3. What are thermoacidophiles? A. bacteria B. archaea C. spirochetes D. cyanobacteria