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Evolutionary History of Biodiversity. Bacteria and Archaea. Three Domains of Life. Fig. 26-21. EUKARYA. Dinoflagellates. Land plants. Forams. Green algae. Ciliates. Diatoms. Red algae. Amoebas. Cellular slime molds. Euglena. Trypanosomes. Animals. Leishmania. Fungi. Sulfolobus. - PowerPoint PPT Presentation
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BACTERIA AND ARCHAEA
Evolutionary History of Biodiversity
Three Domains of Life
Fig. 26-21
Fungi
EUKARYA
Trypanosomes
Green algaeLand plants
Red algae
ForamsCiliates
Dinoflagellates
Diatoms
Animals
AmoebasCellular slime molds
Leishmania
Euglena
Green nonsulfur bacteriaThermophiles
Halophiles
Methanobacterium
Sulfolobus
ARCHAEA
COMMONANCESTOR
OF ALLLIFE
BACTERIA
(Plastids, includingchloroplasts)
Greensulfur bacteria
(Mitochondrion)
Cyanobacteria
ChlamydiaSpirochetes
Prokaryote “Before nucleus”
Characteristics: Unicellular 1-5 μm diameter Cell walls -Maintains shape -Provides protection -Prevents lysis in a
hypotonic environment
Common Shapes of Prokaryotes
Coccus - round Bacillus - rod-shaped Spirillum - spiral-
shaped
Eubacteria Clustering Diplo - a prefix used with the shape name to indicate
pairing of cells. Strepto - a prefix used with the shape name to
indicate chains. Staphylo - a prefix used with the shape name to
indicate clusters
Gram Staining Gram-positive bacteria
purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell.
Gram-negative bacteria outer membrane of
lipopolysaccharides prevents the stain from reaching the peptidoglycan layer.
outer membrane is then permeabilized by acetone treatment, and the pink safranin counterstain is trapped by the peptidoglycan layer
.
Gram-positive and Gram-negative Bacteria
Prokaryotes and a Eukaryotic cell
Fimbriae and Pili
200 nm
Fimbriae
Figure 27.5
Allow bacteria to stick to their substrate or other individuals in a colony
Prokaryotic Flagella
About half of prokaryotes are motile
Prokaryotic FlagellaFlagellum
Filament
Hook
Cell wall
Plasmamembrane
Basal apparatus
50 nm
Generalized reproduction of a prokaryotebinary fission
conjugation
transformation
transduction
1
2
3
4
One cell passes DNA to another through a sex “pilus”
A bacteria takes up DNA from its liquid surroundings
Bacterial viruses carry portions of DNA from one bacteria to another
Like mitosis, DNA replicates and the bacteria divides
The major source of genetic variation in prokaryotes is mutation
Bacteria can share genetic material!!!!! Transformation
Bacteria can share genetic material!!!!! Conjugation
Bacteria can share genetic material!!!!! Transduction
Plasmids
Plasmids
Prokaryote Colonies in Culture
Endospores Bacillus anthracis Can remain viable in harsh
conditions for centuries
Oxygen Requirements Obligate aerobes
Must have oxygenCellular Respiration
Obligate anaerobesAre poisoned by oxygenFermentation or anaerobic respiration
Facultative anaerobesUse oxygen if it is availableNo oxygen – fermentation
Nitrogen FixationUse atmospheric nitrogen as a direct source of nitrogen.
N2 NH4+
One of the most independent organisms on earth: Cyanobacteria (Anabaena)
Cyanobacteria
Gloeothece Nostoc
Fischerella Calothrix
Basic Archaeal Shapes : At far left, Methanococcus janaschii, a coccus form with numerous flagella attached to one side. At left center, Methanosarcina barkeri, a lobed coccus form lacking flagella. At right center, Methanothermus fervidus, a short bacillus form without flagella. At far right, Methanobacterium thermoautotrophicum, an elongate bacillus form.
Archaea
Basic Archaeal Structure : The three primary regions of an archaeal cell are the cytoplasm, cell membrane, and cell wall. Above, these three regions are labeled, with an enlargement at right of the cell membrane structure. Archaeal cell membranes are chemically different from all other living things, including a "backwards" glycerol molecule and isoprene derivatives in place of fatty acids.
Archaea
The side chains in the phospholipids of bacteria and eukaryotes are fatty acids, chains of usually 16 to 18 carbon atoms. Archaea do not use fatty acids to build their membrane phospholipids. Instead, they have side chains of 20 carbon atoms built from isoprene.
Archaea
Archaebacteria Methanogens
Anaerobic bacteria (oxygen is a poison) Produce energy by converting H2 & CO2 into methane gas. Live in swamps & marshes
Extreme Halophiles
“Salt-loving" bacteria use salt to generate ATP for energy.
Thermoacidophiles: Live in extremely acidic environments (pH less than 2) extremely high temperatures (up to 110o C). e.g. geothermal springs at Yellowstone National Park.
Archaebacteria
Bacteria are the decomposers in ecosystems. Some bacteria are symbiotic and live in
association with other organisms. The bacteria that reside in the human intestinal
tract are mutualistic (both benefit); commensalistic (no harm, no benefit) bacteria reside on our skin; and parasitic (only they benefit, we suffer) bacteria cause a wide variety of diseases.
The cyanobacteria are photosynthetic in the same manner as plants.
Prokaryotes Crucial to the Environment
Importance to Humans Associated with good health – natural part of flora Nitrogen fixation Recycling nutrients
Sewage Treatment Decomposers, breaking down the remains of organic matter in dead
plant and animal waste. Used to help clean up environmental disasters caused by humans, such
as chemical and oil spills Foods and medicines
sour cream, yogurt, cottage cheese, sauerkraut and pickles, wine antibiotics
How bacteria cause disease Some bacteria produce toxins that can damage
cells. Endotoxin - made up of lipids and carbohydrates associated with the
outer membrane of gram-negative bacteria. These toxins are some of the strongest poisons known to man and cause violent reactions in host organisms.
Exotoxin - proteins produced inside gram-positive bacteria cells and secreted into the environment. These toxins usually produce fever, weakness, and capillary damage.
Some bacterial proteins cause hypersensitivity reactions which can result in serious illness.
Antibiotics
Penicillin was the first antibiotic. It is highly effective against Gram+ bacteria, but much less so against Gram- bacteria.
Attacks the sugars that hold the capsule together.
Many bacteria are resistant to antibiotics. High mutation rates and misuse of antibiotics has caused a serious health threat that continues to escalate.
Antibiotic Resistance When a population of bacteria is exposed to an Antibiotic,
the most susceptible DIE.
A Few Mutant bacteria that are resistant to the Antibiotic may continue to grow.
A Resistant Population then grows from these Mutant
Bacteria through reproduction and genetic recombination.
These new Population are Antibiotic-Resistant. This has resulted from the Over Use of Antibiotics. Many diseases that were once easy to treat are becoming more difficult to treat.
Antibiotics
Escherichia coli…bad or good?
E.Coli found in the intestines of most mammals, including humansSynthesizes Vitamin BMost strains harmless
E. Coli 0157:H7 - very toxic, found only in digestive tracts of corn-fed cattle
Believed to have gotten its toxicity by conjugation from Shigella
An estimated 73,000 cases of infection and 61 deaths occur each year in the United States alone
Toxin prevents mRNA production in eukaryotic cells- causes cell death
Adapted to an acidic environment- humans and corn-fed cattle, not grass-fed
Killed at 160 degrees F