Download Bacteria

Prokaryotes
Kingdoms Eubacteria &
Archaebacteria
Prokaryote
“Before nucleus”
Characteristics:
• Unicellular
• 1-5 μm diameter
• Cell walls
-Maintains shape
-Provides protection
-Prevents lysis in a
hypotonic environment
PROKARYOTES
EUKARYOTES
Size
1-10 microns
10-100 microns
Complexity
unicellular, rarely sometimes
small colonies
unicellular more
often
multicellular
Membrane
bound
organelles
none
nuclei,
mitochondria,
chloroplasts,
lysosomes,
endoplasmic
reticulum, golgi,
& vacuoles
Prokaryotes
Nucleus
Eukaryotes
no
yes
Chromosomes
single & circular
usually several &
linear
Introns
Rarely
frequent
no
yes
Histones
Prokaryotes
Eukaryotes
Ploidy
haploid
diploid
Mitosis &
Meiosis
absent
present
Sexual
reproduction
none, or
unidirectional
from donor to
recipient
usually, involves
fusion of haploid
gametes
Bacteria
Single-celled prokaryotes
Two kingdoms of bacteria:
• Archaebacteria
• Eubacteria
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 that use salt
to generate ATP for energy.
• Thermoacidophiles: Live in extremely acidic environments
(pH less than 2) that have extremely high temperatures
(up to 110o C). e.g. geothermal springs at Yellowstone
National Park.
Archaebacteria
Eubacteria
• Contains the bacteria commonly referred to as germs.
• This kingdom contains most of the world's bacteria
Eubacteria are classified by:
• Shape
• Clustering
• Respiration
Eubacteria Shape
• 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
Streptococcal (Group A)
Infections
Susceptibility & Resistance
Eubacteria Respiration
• Obligate anaerobes - cannot survive in the presence of
atmospheric oxygen.
• Facultative anaerobes - can live with or without
atmospheric oxygen.
• Obligate aerobes - cannot survive without atmospheric
oxygen.
MRSA
Staphylococcus aureus
The acronym MRSA stands for methicillinresistant Staphylococcus aureus
Maggots Rid Patients Of Antibiotic-resistant Infection, MRSA
— University of Manchester researchers are ridding
diabetic patients of the superbug MRSA - by treating their foot ulcers
with maggots.
ScienceDaily (May 5, 2007)
Gangrene
Tetanus
Necrotizing Fasciitis
Leprosy
Helicobacter pylori
Lyme Disease
Many
antibiotics have
no effect on
gram-negative
bacteria
Gram Staining
•Using a technique called the Gram stain
–Scientists can classify many bacterial species into two
groups based on cell wall composition, Gram-positive
and Gram-negative
Lipopolysaccharide
Cell wall
Peptidoglycan
layer
Cell wall
Outer
membrane
Peptidoglycan
layer
Plasma membrane
Plasma membrane
Protein
Protein
Grampositive
bacteria
Gramnegative
bacteria
20 m
(a) Gram-positive. Gram-positive bacteria have
a cell wall with a large amount of peptidoglycan
that traps the violet dye in the cytoplasm. The
alcohol rinse does not remove the violet dye,
which masks the added red dye.
Figure 27.3a, b
(b) Gram-negative. Gram-negative bacteria have less
peptidoglycan, and it is located in a layer between the
plasma membrane and an outer membrane. The
violet dye is easily rinsed from the cytoplasm, and the
cell appears pink or red after the red dye is added.
Bad bacteria - toxic
Toxins
Substances that disrupts the metabolism of other organisms.
• 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.
Parts of a bacteria cell
• Cell wall - some rigid and others flexible.
• Cell membrane - same as other cells.
• Cytoplasm - same as other cells.
• DNA - a single, circular chromosome (Plasmid) located in the
cytoplasm. Bacteria do not have a nucleus.
• Capsule - a thick, gel-like, protective coating on some bacteria
cells.
• Pili - short, hairlike protein structures on the surface of some
bacteria that help them stick to host cells.
• Flagella - long protein structures that turn to propel some
bacteria cells.
•The cell wall of many prokaryotes
–Is covered by a capsule, a sticky layer of
polysaccharide or protein
200 nm
Capsule
Figure 27.4
Fimbriae and pili
–allow bacteria to stick to their substrate or
other individuals in a colony
Fimbriae
200 nm
Figure 27.5
Taxis – movement toward or
away from a stimulus
+ chemotaxis = movement
toward chemical
- chemotaxis = movement
away from chemical
Flagellum
Filament
50 nm
Cell wall
Hook
Basal apparatus
Plasma
membrane
Reproduction
• Asexual, by binary fission - the DNA replicates and
then the cell pinches inward and splits in two.
• Conjugation - two cells exchange a portion of their DNA
across a bridge formed between the cells. New material
replaces old material in the cell. While this increases
the genetic variability in the organisms, it is not true
sexual reproduction.
• Endospores - during adverse conditions, the DNA is
encased in a protective envelope. This endospore can lie
dormant for years or until favorable conditions return.
Binary
Fission
Conjugation
Endospores
Can remain viable in harsh conditions for centuries
Endospore
0.3 m
Figure 27.9
Prokaryotic Metabolism
Antibiotics
Drugs that fight bacteria by interfering with their
cellular functions.
• PENICILLIN interferes with cell wall synthesis.
• TETRACYCLINE interferes with protein synthesis.
• Many antibiotics are derived from chemicals that bacteria or
fungi produce.
•
• SULFA DRUGS - antibiotics that are synthesized in
laboratories
• Many Antibiotics are able to affect a wide variety of
organisms; they are called BROAD SPECTRUM
ANTIBIOTICS.
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.
USEFUL BACTERIA
• Used in Sewage Treatment, and as Decomposers,
breaking down the remains of organic matter in dead
plant and animal waste. Recyclers, returning nutrients
back to the environment.
• Food production. Bacteria help us make buttermilk, sour
cream, yogurt, cottage cheese, sauerkraut and pickles.
• Used in industrial chemical production. They produce
organic chemicals and fuels. They’re used in the mining of
minerals and their products are used as insecticides.
• Used to help clean up environmental disasters caused by
humans, such as chemical and oil spills.
•Prokaryotes are the principal agents in
bioremediation
–The use of organisms to remove pollutants from
the environment