Presentation is loading. Please wait.

Presentation is loading. Please wait.

Welcome to Biology 213 Into the Prokaryotes! Into the Prokaryotes!

Similar presentations


Presentation on theme: "Welcome to Biology 213 Into the Prokaryotes! Into the Prokaryotes!"— Presentation transcript:

1 Welcome to Biology 213 Into the Prokaryotes! Into the Prokaryotes!

2 The History of Life

3 Organizing Life As We Know It Today Robert Whittaker, 1969

4 Carl Woese’s Tree Based on ssuRNA Sequence Analysis!

5 Organizing Life: The Debate Our tour begins with the prokaryotic kingdoms/domains…

6 " The key to taking the measure of biodiversity lies in a downward adjustment of scale. The smaller the organism, the broader the frontier and the deeper the unmapped terrain...... A lifetime can be spent in a Magellanic voyage around the trunk of a single tree." -(E. O. Wilson, 1995)

7 The Prokaryotes: Characteristics Source: www.agen.ufl.edu/~chyn/age2062/ lect/lect_06/lect_06.htmwww.agen.ufl.edu/~chyn/age2062/ lect/lect_06/lect_06.htm

8 No membrane- bound nucleus No membrane- bound nucleus Single chromosome (+plasmids) Single chromosome (+plasmids) Typically have a Cell Wall Typically have a Cell Wall Reproduction by prokaryotic fission Reproduction by prokaryotic fission Enormous metabolic diversity! Enormous metabolic diversity! The Prokaryotes: Characteristics Source: micro.magnet.fsu.edu/cells/ bacteriacell.htmlmicro.magnet.fsu.edu/cells/ bacteriacell.html

9 Prokaryotic Cell Walls

10 Many Prokaryotes have Capsules outside the cell wall Capsules have a role in adherence, virulence, protection, securing nutrients, and cell-to-cell recognition. Capsules have a role in adherence, virulence, protection, securing nutrients, and cell-to-cell recognition. Capsule-producing bacillus-shaped bacteria.

11 Many Prokaryotes also have surface appendages called PILI Prokaryotes such as this E coli, strain 0157:H7 use pili to adhere to one another or to a surface Prokaryotes such as this E coli, strain 0157:H7 use pili to adhere to one another or to a surfaceE coli, strain 0157:H7E coli, strain 0157:H7

12 Many Prokaryotes are Motile Mechanism 1 = Flagella Analogous to Eukaryotic Flagella! Chains of Flagellin

13 Many Prokaryotes are Motile Mechanism 2 = Helical Filaments Mechanism 3 = “Slimy Threads” Spirochetes: A. Cross section of a spirochete showing the location of endoflagella between the inner membrane and outer sheath; B. Borrelia burgdorferi, the agent of Lyme disease; C. Treponema pallidum, the spirochete that causes syphilis. Source: www.bact.wisc.edu/Bact303/ MajorGroupsOfProkaryotes www.bact.wisc.edu/Bact303/ MajorGroupsOfProkaryotes

14 Many Prokaryotes are Motile This results in taxis, or the movement towards or away from a stimulus. Many prokaryotes can move directionally along gradients of light, chemicals, or even magnetic fields !

15 Prokaryotes can be distinguished by SHAPE The three most common shapes: Rod-shaped bacilliSpherical Cocci Helical Spirillum Prokaryotes that clump together = staphylo- Prokaryotes that form chains = strepto-

16 The Prokaryotes: Characteristics Ubiquitous! Bacteria can be found virtually anywhere, including in dental plaque (left) and on the surface of a contact lens (right). Courtesy MicrobeLibrary.org

17 Abundant! A single teaspoon of topsoil contains about a billion bacterial cells (and about 120,000 fungal cells and some 25,000 algal cells). The human mouth is home to more than 500 species of bacteria. Source: www.microbeworld.org Abundant! A single teaspoon of topsoil contains about a billion bacterial cells (and about 120,000 fungal cells and some 25,000 algal cells). The human mouth is home to more than 500 species of bacteria. Source: www.microbeworld.org The Prokaryotes: Characteristics Nitrifying bacteria cross section Photo credit: Mary Ann Bruns, Center for Microbial Ecology, Michigan State University

18 Prokaryotes reproduce rapidly through binary fission The Prokaryotes: Characteristics

19 Prokaryotes reproduce asexually, but still exchange genetic information via transformation, conjugation, and transduction The Prokaryotes: Characteristics Mutation is also a very important source of genetic variation in prokaryotes!

20 Some prokaryotes can form resistant cells called ENDOSPORES The chromosome is replicated and becomes encased in an extremely durable wall The Prokaryotes: Characteristics

21 Terms to Describe Metabolic Diversity Categorize prokaryotes according to how the acquire ENERGY and a CARBON SOURCE Can use LIGHT = PHOTOTROPHS or CHEMICALS = CHEMOTROPHS Need only CO 2 = AUTOTROPHS or Need 1+ ORGANIC NUTRIENTS = HETEROTROPHS

22

23 Example: An Alternate Strategy How would I describe a bacteria that could do this??

24 Most Prokaryotes are CHEMOHETEROTROPHS Can be either SAPROBES - absorb nutrients from dead organic matter or PARASITES - absorb nutrients from living hosts

25 Chemoheterotrophic Prokaryotes Utilize a Diverse Assortment of Organic Nutrients Some prokaryotes utilize very specific media; Some, such as E. coli, can utilize a variety of carbon sources Lactobacillus

26 Relationships with Oxygen Obligate Aerobes (cannot live without O 2 ) Obligate Aerobes (cannot live without O 2 ) Facultative Aerobes (use O 2 if present, but can do fermentation) Facultative Aerobes (use O 2 if present, but can do fermentation) Obligate Anaerobes (poisoned by oxygen!) Obligate Anaerobes (poisoned by oxygen!)

27 Nitrogen Metabolism Fixation = N 2  NH 3 (ammonia)

28 Many Prokaryotes Process Nitrogen 1. Denitrification - nitrite (NO 2 ) or nitrate (NO 3 - ) converted to Nitrogen Gas (N 2 ) 2. Nitrogen Fixation- convert atmospheric nitrogen (N 2 ) to ammonium (NH 4 + ) Anabaena

29 This Enormous Diversity of Strategies Probably Evolved Early Earliest Strategy?

30 This Enormous Diversity of Strategies Probably Evolved Early Probably heterotrophic… Glycolysis! Natural Selection would eventually favor photosynthesis

31 The Archaea

32 Prokaryotes: the Archae Thermophiles like unusually hot temperatures. A few species have been found to survive even above 110 degrees Celsius (water boils at 100 degrees Celsius). Psychrophiles like extremely cold temperatures (even down to -10 degrees Celsius). Halophiles thrive in unusually salty habitats. Some can thrive in water that’s 9% salt; sea water contains only 0.9% salt. Acidophiles prefer acidic conditions; Alkaliphiles prefer very alkaline environs. Thermophiles like unusually hot temperatures. A few species have been found to survive even above 110 degrees Celsius (water boils at 100 degrees Celsius). Psychrophiles like extremely cold temperatures (even down to -10 degrees Celsius). Halophiles thrive in unusually salty habitats. Some can thrive in water that’s 9% salt; sea water contains only 0.9% salt. Acidophiles prefer acidic conditions; Alkaliphiles prefer very alkaline environs. Source: www.microbeworld.org

33 Prokaryotes: the Archae Methanogens use CO 2 to oxidize H 2, producing methane as a waste product. Methanogens are strict anaerobes! This appears to be a monophyletic group that evolved very early. Methanogens use CO 2 to oxidize H 2, producing methane as a waste product. Methanogens are strict anaerobes! This appears to be a monophyletic group that evolved very early.

34 Prokaryotes: the Archae No peptidoglycan in their cell walls No peptidoglycan in their cell walls Use multiple RNA Polymerases Use multiple RNA Polymerases Some of their genes have introns Some of their genes have introns They are not affected by antibiotics They are not affected by antibiotics They use histones to organize their DNA They use histones to organize their DNA Do these seem like prokaryotic or eukaryotic traits?? Is this consistent with what we’ve learned from rRNA?

35 The “Bacteria”

36 The Proteobacteria Gram negative Gram negative Diverse: photoautotrophs, chemoautotrophs, heterotrophs, may be anaerobic or aerobic Diverse: photoautotrophs, chemoautotrophs, heterotrophs, may be anaerobic or aerobic Five subgroups fall out: Five subgroups fall out: Alpha, Beta, Gamma, Delta, and Epsilon Proteobacteria

37 The Alpha Proteobacteria Alfalfa (Medicago sativa) S. meliloti cells SEM courtesy of William Margolin. Most symbiotic/parasitic Mitochondria evolved from aerobic alphas! Famous Alphas include: Nitrogen fixing symbionts, the plant pathogen Agrobacterium, and Rocky Mountain Spotted fever

38 The Beta Proteobacteria Diverse group, includes Nitrosomonas. Nitrosomas converts ammonium to nitrite Diverse group, includes Nitrosomonas. Nitrosomas converts ammonium to nitrite Also includes Thiobacillus, the sulfur and iron oxidizing bacteria (obligate chemoautotrophs, using inorganic compounds as electron donors and carbon dioxide as the carbon source) Also includes Thiobacillus, the sulfur and iron oxidizing bacteria (obligate chemoautotrophs, using inorganic compounds as electron donors and carbon dioxide as the carbon source)

39 The Beta Proteobacteria More famous Beta Proteobacteria: Bordetella pertussis Neisseria meningitidis. Causes meningococcal meningitis Neisseria gonorrhoeae. Causes gonorrhea, one of the most common sexually-transmitted diseases ( STDs ): 355,642 cases in the U.S. in 1998

40 Diverse group including photosynthetic sulfur bacteria Diverse group including photosynthetic sulfur bacteria Famous heterotrophic members include: Famous heterotrophic members include: Legionella, Salmonella, Vibrio cholerae, Escherichia coli, and Yersinia pestis Legionella, Salmonella, Vibrio cholerae, Escherichia coli, and Yersinia pestis The Gamma Proteobacteria Buboes are a symptom of the bubonic plague. (Photo courtesy Jose Quintas - University of Chicago)

41 Include the very elaborate myxobacteria- soil bacteria that secrete a slimy substratum and produce fruiting bodies when conditions become poor Include the very elaborate myxobacteria- soil bacteria that secrete a slimy substratum and produce fruiting bodies when conditions become poor Also includes bacterial predators, the bdellovibrios Also includes bacterial predators, the bdellovibrios The Delta Proteobacteria

42

43 Closely related to the deltas Closely related to the deltas Includes Helicobacter pylori (stomach ulcers) and Campylobacter jejuni (the bacterium most frequently implicated in gastrointestinal upsets) Includes Helicobacter pylori (stomach ulcers) and Campylobacter jejuni (the bacterium most frequently implicated in gastrointestinal upsets) The Epsilon Proteobacteria Scanning electron microscope image of Campylobacter jejuni, illustrating its corkscrew appearance and bipolar flagella. Source: Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, Virginia.

44 The “Bacteria”

45 The Chlamydias All parasitic, living inside animal cells (dependent on host for ATP) All parasitic, living inside animal cells (dependent on host for ATP) Gram-negative and lack peptidoglycan in their cell walls Gram-negative and lack peptidoglycan in their cell walls Famous Chlamydias: Chlamydia trachomatis causes blindness and nongonococcal urethritis (most common STD in the US) Famous Chlamydias: Chlamydia trachomatis causes blindness and nongonococcal urethritis (most common STD in the US) Scanning electron micrograph of a chlamydia inclusion body leaving a host cell in a dramatic fashion. The inset shows a closeup of the elementary bodies breaking free of the inclusion body. Source: CDC

46 The Spirochetes Long Cells (0.25mm!), uses internal filament to produce corkscrew- like movement Long Cells (0.25mm!), uses internal filament to produce corkscrew- like movement Famous spirochetes include: Treponema pallidum (syphilis) and Borrelia burgdorferi (Lyme disease) Famous spirochetes include: Treponema pallidum (syphilis) and Borrelia burgdorferi (Lyme disease) Source: dev.triothinkquest.orgdev.triothinkquest.org

47 The Gram-Positive Bacteria All gram-positive and a few gram negative All gram-positive and a few gram negative Includes the actinomycetes (tuberculosis, leprosy, + Streptomyces) Includes the actinomycetes (tuberculosis, leprosy, + Streptomyces) Also includes solitary species (Bacillus, Staphylococcus, Streptococcus) Also includes solitary species (Bacillus, Staphylococcus, Streptococcus)

48 Another Unusual “Gram +” Electron micrograph of thin-sectioned mycoplasma cells. Cells are bounded by a single membrane. (Photo: RM Cole, Bethesda, Maryland).

49 The “Bacteria”

50 The Cyanobacteria Only prokaryotes with oxygenic photosynthesis (early endosymbionts?) Only prokaryotes with oxygenic photosynthesis (early endosymbionts?) Solitary or colonial in aquatic environments Solitary or colonial in aquatic environments Some filamentous forms can fix nitrogen Some filamentous forms can fix nitrogen

51 Some of the Ecological Impacts of Prokaryotes Nutrient Cycling Decomposers return nonliving matter to the pool of available organic compounds Autotrophic prokaryotes also create organic compounds from CO 2, making these available at higher trophic levels

52 Some of the Ecological Impacts of Prokaryotes Prokaryotes are key players in a variety of symbiotic relationships including mutualism, commensalism, and parasitism Symbiotic Relationships

53 Some of the Ecological Impacts of Prokaryotes Human Disease Pathogens usually cause illness by the production of endo- and exotoxins Endotoxins- components of the outer membranes of some gram-negative bacteria (Salmonella) Exotoxins - proteins secreted by prokaryotes (Clostridium botulinum, some E. coli strains)

54 What happened to this guy?? Hint: Many bacteria secrete exotoxins… (1 g of botulism toxin can kill 1,000,000 people!)

55 Some of the Ecological Impacts of Prokaryotes We owe much of our understanding of the role of bacteria in producing disease to Robert Koch. He established four criteria (Koch’s postulates; 1890)… Human Disease

56 Koch’s Postulates 1. The bacterium must be present in every disease case. 2. The bacterium must be isolated from the disease case and grown in pure culture. 3. The specific disease must be reproduced from pure culture in a healthy susceptible host inoculated with the bacterium. 4. The bacterium must be recoverable from the susceptible host.

57 Koch’s Postulates: A Practical Approach?! Barry J. Marshall and J. Robin Warren were awarded the 2005 Nobel Prize in Physiology or Medicine for their discovery of the bacterium Helicobacter pylori and its role in gastritis and peptic ulcer disease. The Nobel Prize in Physiology or Medicine 2005

58 Some of the Ecological Impacts of Prokaryotes Research and Technology Bioremediation: Rhodococcus sp. (at right) has been engineered to breakdown PCB’s, persistent industrial pollutants. (Photo/UBC Bioimaging Facility)


Download ppt "Welcome to Biology 213 Into the Prokaryotes! Into the Prokaryotes!"

Similar presentations


Ads by Google