Download Bacteria

Bacteria
Prokaryotes
– Unicellular, organisms that lack a nucleus
– Much smaller than most eukaryotic cells
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Kingdoms
• Kingdoms
– Eubacteria
– Archaebacteria
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Eubacteria
• Larger of the two
• Live almost everywhere
– Water, land, and within the human body
Anabaena
E. coli
Streptomyces griseus
Soil bacteria
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Cell-Surface Structures
• One of the most important features of nearly all
prokaryotic cells is their cell wall.
– Functions
• Maintains cell shape
• Provides protection
• Prevents cell from bursting in hypotonic
environment
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• Within the cell wall is a cell membrane
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HONORS External structures - Peptidoglycan
• Carbohydrate in the cell wall of eubacteria only.
peptidoglycan
Plasma membrane
Some eubacteria have a second membrane outside the cell membrane
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Archaebacteria – survive in extreme environments
•
Their membrane lipids are different from those of
eubacteria
• They lack peptidoglycan
• They look very similar to eubacteria
Morning Glory Pool – Yellowstone
Thermoacidophiles
230 degrees farenheit
Figure 27.1
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Significance of DNA sequences of key archaebacterial genes
• They are more like those of eukaryotes than
those of eubacteria
• Scientists reason that archaebacteria may be
the ancestors of eukaryotes
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Example of archaebacteria
• Extreme halophiles
– Live in high saline environments
Figure 27.14
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Example of archaebacteria
• Methanogens
– Produce methane as a waste product
– Live in oxygen free environments, such as
thick mud and the digestive tracts of animals.
Bacteria in
digestive tract
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Four Characteristics Used to identify Prokaryotes
• Shape
• Chemical nature of cell wall
• Way they move (motility)
• Way they obtain energy
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The shapes of Prokaryotes
• Prokaryotic cells have a variety of shapes
– Rod – called bacilli
– Spherical – called cocci
–
Corkscrew – called spiral
Figure 27.2a–c
1 m
(a) Spherical (cocci)
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2 m
(b) Rod-shaped (bacilli)
(c) Spiral
5 m
Motility
• Most motile bacteria propel themselves by flagella
– Which are structurally and functionally different
from eukaryotic flagella
– Some do not move at all
Flagellum
Filament
50 nm
Cell wall
Hook
Basal apparatus
Figure 27.6
Plasma
membrane
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Metabolic Diversity (modes of nutrition)
• Photoautotroph – carries out photosynthesis
(light and inorganic molecules) like plants
• Chemoautotroph – energy from chemical
reactions involving inorganic molecules
(sulfur, iron,)
• Heterotroph – take in organic molecules and
breaks them down
• Photoheterotroph- captures sunlight for
energy and also needs organic molecules as
a carbon source
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Photoautotroph
• The cyanobacterium
–
The cells
exchange,
nitrogen for
carbohydrates
contain a bluish pigment and chlorophyll a
Photosynthetic
cells
Heterocyst
Figure 27.10
perform nitrogen fixation – convert nitrogen from
20 Heterocysts
m
atmosphere into ammonia
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Chemoautotrophs
• Live near hydrothermal vents
• Obtain energy from hydrogen sulfide gas that
flows from the vents
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The way Prokaryotes release energy. Oxygen requirements
• Obligate aerobes
– Require a constant supply of oxygen
• Obligate anaerobes
– Must live in the absence of oxygen
– Are poisoned by oxygen
• Facultative anaerobes
– Can survive with or without oxygen
– Switch between cellular respiration and
fermentation
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Growth and Reproduction
• Prokaryotes reproduce quickly by binary fission
• A form of asexual reproduction
– A cell grows to nearly double its size
– Replicates its DNA
– Divides in half producing two identical “daughter” cells
Can divide every 1–3 hours
• Some can reproduce every 20 min.
• How do they stay in control?
– Use up food supply, poison themselves with waste,
consumed by other organisms
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Binary Fission – most bacteria reproduce this way.
•
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Conjugation
• A bacterial mating process
• A hollow bridge forms between two cell and
genes move from one cell to another.
Transfer takes place
through sex pili
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What most bacteria need to live.
• Moisture
• A certain temperature
• Nutrition
• darkness
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adaptation
• Many prokaryotes form endospores – an
internal wall that encloses DNA and cytoplasm.
– Which can remain viable in harsh conditions for
centuries
– When conditions are favorable again, it absorbs water
and resumes growth
Boiling doesn’t kill
endospores.
Endospore
Autoclaving does.
(High tem. And
pressure.)
Figure 27.9
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0.3 m
Importance of Bacteria
• Decomposers
– Attack and digest dead tissue
• Break it down into simpler material
• This material is released into the soil
•
Without decomposers life would not continue
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Nitrogen Metabolism
• Prokaryotes can metabolize nitrogen
– Plants and animals need nitrogen to make
amino acids, which help build proteins.
• Nitrogen fixation
– Some prokaryotes convert atmospheric
nitrogen to ammonia, which is the form that
plants can use.
– Plants use the nitrogen to build amino acids
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Nitrogen Fixation
•
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Symbiotic Relationships
• Many prokaryotes
– Live with other organisms in symbiotic
relationships such as mutualism and
commensalisms
Figure 27.15
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Uses in technology
• Prokaryotes are the principal agents in
bioremediation
– The use of organisms to remove pollutants
from the environment
Digest
petroleum
Figure 27.17
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Bacteria adapted to extreme environments
• May be a rich source of heat-stable enzymes.
• Can be used
– In medicine
– Food production
– And industrial chemistry
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Bacteria
• Some bacteria are pathogens
– A pathogen is a disease-causing agent
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How can bacteria cause disease?
• Some damage the tissues of the infected
organism directly by breaking them down for
food.
– For example, the bacteria that cause
tuberculosis break down lung tissue
• Others release toxins that harm the body
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Bacterial diseases
•
Prokaryotes cause about half of all human diseases
–
Examples
•
Lyme disease
•
Tetnus
•
Syphilis
•
Gonorrhea
•
Tuberculosis (TB)
•
Legionnaire's disease
•
Anthrax
•
Meningitis
•
Pertussis
•
Escherichia coli and Salmonella
–
Food poisoining
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Controlling bacteria
• Antibiotics
– Compounds that block the growth and
reproduction of bacteria
• Our life expectancy has increased due to an
increased understanding of how to prevent and
cure bacterial infections.
• Vaccinations
– Usually a shot that contains some of the
bacteria to build up ones immunity
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Antibiotics
• Some inhibit the enzymes that allow DNA replication
• Some inhibit the synthesis of the cell wall
• Some inhibit protein synthesis
• Cipro
• Amoxicillin
• Z pack
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Vaccines
• Examples
– TB vaccine
• Tuberculosis
• Meningococcal
• Anthrax
• Tetanus
• Pneumococcal
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Controlling Bacteria
• Sterilization – destroying bacteria by subjecting
them to either great heat or chemical action
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Controlling Bacteria
• Chemical Action
Antiseptics-kill bacteria on living things.
-alcohol, hydrogen peroxide, iodine
Other (not an antiseptic)
soap, toothpaste, mouthwash
Disinfectants-kill bacteria on non-living things
-Mr. Clean, bleach
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Heat Killing
• Dry heat
– Open flame
• Moist heat
– Autoclave
• 15 lb/in2 at 121 degree Celsius
• Pasteurization
– Heating (kills, does not sterilize)
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At Low temperatures, bacteria in the food will take much longer to multiply
• Refrigeration
– Keeping foods cold
• Freezing
• Drying
– No water inhibits growth
• Freeze drying
– For long term storage
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Change the pH
• More acidic
Mustard, and
tomato
products
have a higher
acid content
and
therefore,
help prevent
bacterial
growth.
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Other means of controlling bacteria
• Radiation
– UV light
• Filtration
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Human Uses of Bacteria
• Used in the production of a variety of foods
– Cheese, yogurt, buttermilk, and sour cream.
– Pickles, sauerkraut
•
http://www.bacteriamuseum.org/cms/Food-And-Water-Safety/good-bacteria-in-food.html
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Human uses of bacteria (they’re not all bad)
• Experiments using prokaryotes
– Have led to important advances in DNA
technology
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Human Uses
• Experiments using prokaryotes
– Have led to important advances in DNA technology
– Genetic Engineering
• Ex. Cloning
• Used in industry
– Oil eating bacteria
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Useful
• Prokaryotes are also major tools in
– Mining
– The synthesis of vitamins
– Production of antibiotics, hormones, and other
products
Poor quality copper ore, which is bound up in a sulfide matrix, is dumped outside a
mine and treated with sulfuric acid to encourage the growth of T. ferooxidans. As the
bacteria chew up the ore, copper is released and collected in solution. The sulfuric
acid is recycled.
Microbes may be used to elaborate precursors in the making of
Vitamins A, C, and the B family. Using sugarbeet molasses as a
growth medium, Pseudomonas denitrificans is made to produce
Vitamin B12. Members of the genus Propionibacterium are also
used to make this vitamin.
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Useful Bacteria
• Used in sewage treatment
• Live in the intestine of animals
– Make vitamins
– Help digest food.
Research suggests that the relationship between gut flora and
humans is not merely commensal (a non-harmful coexistence),
but rather a symbiotic relationship.[3] Though people can survive
without gut flora,[4] the microorganisms perform a host of useful
functions, such as fermenting unused energy substrates, training
the immune system, preventing growth of harmful, pathogenic
bacteria,[2] regulating the development of the gut, producing
vitamins for the host (such as biotin and vitamin K), and
producing hormones to direct the host to store fats.
Bacteria make up most of the flora in the colon[7] and up to 60%
of the dry mass of feces.[2] Somewhere between 300[2] and 1000
different species live in the gut,[3] with most estimates at about
500.[4][5][8] However, it is probable that 99% of the bacteria come
from about 30 or 40 species.[9
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