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Prokaryotes
• Bacteria were first
discovered in the late 1600’s
by Anton van
Leeuwenhoek, using the
microscope he invented.
• bacteria found in the dental
plaque of two old men who
never cleaned their teeth.
Prokaryote Structure
• Prokaryotes are simple cells.
NO NUCLEUS- The DNA is
loose in the cytoplasm in the
form of a NUCLEOID
-
The RIBOSOMES are found in
the cytoplasm.- NO
ORGANELLES
• Has a CELL MEMBRANE and
CELL WALL (peptidoglycan not
cellulose)
• Some have an outer CAPSULE
which is sometimes called a
SLIME LAYER or PILI which are
tiny stickers
• Bacteria move using FLAGELLA:
may have one or many
Relationship to Oxygen
• For more than half of Earth’s history, oxygen wasn’t
present in the atmosphere. Many bacteria evolved
under anaerobic conditions.
• Classification:
• OBLIGATE AEROBES(need oxygen to survive)
• OBLIGATE ANAEROBES (killed by oxygen)
• AEROTOLERANT(don’t use oxygen, but survive it).
•
FACULTATIVE AEROBES(use oxygen when it is
present, but live anaerobically when oxygen is
absent).
2 Bacteria Kingdoms
• Kingdom Archaebacteria - are ancient
bacteria that live in extreme
environments
• Kingdom Eubacteria - are generally
referred to as bacteria or germs, and are
considered more recent. Most types of
bacteria belong in this kingdom.
• First appeared approximately 3.7 BYA
The Archaebacteria:
• do not have peptidoglycan in
their cell walls
• have ribosomes similar to
eukaryotes
• have unique lipids in their
plasma (cell) membranes
The Archaebacteria also:
• have some genes that resemble
eukaryotic genes
• usually are not pathogenic (they
don’t usually make us sick!)
• live in extreme environments:
–high concentrations of salt
–extremes of pH and temperature
3 Archaebacterial Groups
• Methanogens- turn H2 and CO2 into
methane (CH4)
• Halophiles- organisms that live in
environments with extremely high
salt concentrations
• Thermoacidophiles = live in
extremely hot, acid environments
Methanogens
• anaerobic bacteria that get energy by
turning H2 and CO2 into methane
(CH4)
• live in mud, swamps, and the guts of
cows, humans, termites and other
animals
Halophiles
• are organisms that live in environments
with extremely high salt concentrations
–some extreme halophiles can live in
solutions of 35 % salt. (seawater is only
3% salt!)
• halophile means “salt loving”
• most halophiles are aerobic and
heterotrophic; others are anaerobic and
photosynthetic, containing the pigment
bacteriorhodopsin
Halophile
Environments
solar salterns
Owens Lake,
Great Salt Lake,
coastal splash
zones,
Dead Sea
Thermoacidophiles
• Like temperature and pH extremes
– Hot = up to 110ºC
– Cold = down to 1ºC
– Acid = as low as pH 2
– Alkali = as high as pH 9
• they are chemoautotrophs, using H2S
• the first Extremophile was found about
30 years ago
Thermophile
Environments
Hydrothermal Vents in
the ocean, and
Obsidian Pool in
Yellowstone
National Park
EUBACTERIA--• Germs
• PATHOGENS- an organisms that makes
another organism sick by living inside
• Examples- bacteria, viruses, fungi, parasites
CLASSIFIED BY METABOLISM
AUTOTROPHIC
PHOTOAUTOTROPHIC
CHEMOAUTOTROPHIC
HETEROTROPHIC
AEROBIC
ANAEROBIC
Bacteria are Named by Shape
• Cocci (ball-shaped)
–Streptococcus mutans
• Bacillus (rod-shaped)
–Clostridium botulinum
• Spirilli (spiral-shaped)
–Treponema palladium
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Bacteria are Named by
Arrangement
• Paired: diplo
• Grape-like clusters: staphylo
• Chains: strepto
Examples
• Streptococcus: chains of spheres
• Staphylospirillum: Grapelike clusters
of spirals
• Streptobacillus: Chains of rods
CLASSIFIED BASED ON THEIR CELL
WALL
The Gram stain, which divides most clinically
significant bacteria into two main groups, is
the first step in bacterial identification.
BACTERIA WITH THICK CELL WALLS – are called
GRAM + and will stain purple
BACTERIA WITH THIN CELL WALLS- are called
GRAM – and will stain pink
The Gram stain has four steps:
• 1. crystal violet, the primary stain: followed by
• 2. iodine, which acts as a mordant by forming
a crystal violet-iodine complex, then
• 3. alcohol, which decolorizes, followed by
•
4. safranin, the counterstain.
In Gram-positive bacteria, the purple crystal violet stain is
trapped by the layer of peptidoglycan which forms the outer
layer of the cell. In Gram-negative bacteria, the outer
membrane of lipopolysaccharides prevents the stain from
reaching the peptidoglycan layer. The outer membrane is then
permeabilized by acetone treatment, and the pink safranin
counterstain is trapped by the peptidoglycan layer.
Is this gram stain positive or negative?
Identify the bacteria.
Is this gram stain positive or negative?
Identify the bacteria.
Reproduction of Bacteria
•Binary Fission- the process of one organism
dividing into two organisms
•Fission is a type of asexual reproduction
•Asexual reproduction- reproduction of a living thing from only one parent
How?...
The one main (circular) chromosome makes a
copy of itself
Then it divides into two
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Reproduction of Bacteria
BINARY FISSION
Bacteria dividing
Completed
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Reproduction of Bacteria
•The time of reproduction depends on how
desirable the conditions are. (example- leaving
milk out vs keeping them in the refridgerator)
•Some can reproduce every 20 minutes
(one bacteria could be an ancestor to millions in
less than a day)
“EXPONTENTIAL GROWTH”
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Bacterial Cell & Nucleiod DNA Ring
Step 1
DNA replicates
Step 2
DNA (chromosomes) move to
opposite ends and attach to cell
membrane
Step 3-Cell grows in the
middle
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How do bacteria survive in
inclimate environments?
• CAPSULES-(Gram -) prevent bacteria from
drying out
• GLYCOCALYX- capsule with a sticky substance
that allows the bacteria to stick to a specific
environment
• ENDOSPORES- dormant structure that
surrounds the DNA in Gram + bacteria
ENDOSPORE
How do Bacteria become drug
resistant? (DNA)
• MUTATIONS• PLASMIDS- tiny rings of DNA that can be
transferred from one bacteria to another
• TRANSFORMATION-absorbing DNA from the
environment (example- other bacteria that
have died)
• TRANSDUCTION- Virus carries DNA from one
bacteria to the next
• CONJUGATION- passing of DNA from one
bacteria to the next
TRANSFORMATION
CONJUGATION
STEP 1- Bacteria replicates a PLASMID
STEP 2- Bacteria creates a CONJUGATION
BRIDGE from one bacteria to the next
STEP 3- PLASMID crosses the CONJUGATION
BRIDGE
STEP 4- PLASMID may or may not become part
of the chromosome of the new bacteria
TRANSDUCTION
CONJUGATION
CONJUGATION
BENEFITS OF BACTERIA
1. DECOMPOSERS—Saprophytes- breakdown dead
organisms and place nutrients back into the soil
(important in the carbon cycle, nitrogen cycle)
2. NITROGEN FIXATION- extremely important in the
nitrogen cycle- bacteria called RHIZOBIUM- are
found in the roots of LEGUMES (bean plants). These
rhizobium can turn unusable nitrogen into a type of
nitrogen that plants can use to make proteins.
(examples- crop rotationing)
BENEFITS OF BACTERIA
3. Make foods like- PICKLES, CHEESE, BUTTER,
YOGURT (Lactobacilli and bifidobacterium),
SAUERKRAUT , SAUSAGES, COCOA and COFFEE
BEANS—SOUR DOUGH BREAD
4. Live in our digestive systems (ENTERIC
BACTERIA)- help us breakdown hard to
digest food and produces VITAMIN K
(example- E. coli)
5. Live on our skin– Staphylococcus epidermis
protects us from other bacterial invaders
BIOTECHNOLOGY WITH BACTERIA
6. USING BACTERIA to clean up OIL SPILLSbreak it down and give off carbon dioxide and
water
7. USING BACTERIA to de-thatch you YARD and
in PEST CONTROL
8. USING BACTERIA to produce certain
PROTEINS and INSULIN used in medicine
PROBLEMS WITH BACTERIA
• EUTROPHICATION
“population bloom” of
bacteria (fungi or
plants) that use up all
the nutrients in a lake,
pond- most commonly
OXYGEN that will kill off
all animals in the area
PROBLEMS WITH BACTERIA
PATHOGENS- give off toxins that cause diseases
EXOTOXINS- toxins released by living bacteriausually made by Gram + bacteria- (Exampletetanus)
ENDOTOXINS- toxins that are released when the
cell dies- from the capsule of Gram – bacteria
(Example- E. coli)
ANTIBIOTICS
Defined as drugs that
“combat” bacteria that
interfere with their
cellular functions
ANTI= not or against
BIO= living
Types of ANTIBIOTICS (See list on
pg 479)
• PENICILLIN- interferes with the bacteria’s
ability to make a cell wall (Gram +)
• TETRACYCLINE- interferes with the bacteria’s
ability to make proteins-- BROAD SPECTRUM
ANTIBIOTIC