Transcript Bacteria - robertschem

Bacteria
pp. 108 to 112
EUKARYOTES (TRUE NUCLEUS)
(PLANT AND ANIMAL CELLS)
PROKARYOTES (PRE-NUCLEUS)
(BACTERIA)
Nucleus
No nucleus
Lots of chromosomes
Usually one chromosome + some plasmids
Mitochondria
No mitochondria
Chloroplasts in plant cells
No chloroplasts
Larger
Smaller
Mitotic cell division
Simple binary fission (split into two)
Flagellum in animal cells (some)
Simple flagellum
Bacteria: General Info
• Two kingdoms: Archaebacteria
(early bacteria) and Eubacteria
• Unicellular (organism is singlecelled); can be grouped into
colonies
• Do well in damp environments,
will become inactive in dry
environments
• No nucleus but has single
chromosome and small
plasmids, which is also genetic
information
Archaebacteria – 3 groups
Most live without O2 in extreme environments
• Thermophiles
– live in envs hotter than 45°C (eg. Hot springs)
• Methanogens
– No O2, but abundant CO2/H2; produce methane gas
– Swamps, marshes, volcanoes, intestines of mammals
• Halophiles
– Live in salty environments (eg. Salt lakes, salt flats)
Thermophiles in hot springs of Yellowstone Nat. Park
Methanogens in cow
intestines is a source of
fossil fuel emission.
However, methane gas
can be used as a source
of electricity since it is
a natural gas!
Halophiles love salt.
Middle picture is the
Dead Sea!
Eubacteria & Structure
• Most bacteria fall into this kingdom
• Flagella – act as a propeller to
move cell
• Capsule – sticky coat, protective
layer (protects from host’s
immune system), seen in
disease-causing bacteria
• Pili – help bacteria attach to each
other and surface, also helps
with movement
• Genetic material – floats in
cytoplasm, no nucleus, 1
chromosome and several
plasmids
• Ribosomes, cell membrane, cell
wall, cytoplasm – see Unit 1
Classifying Bacteria
1.
2.
3.
4.
By Shape
By Gram Staining
By whether they need O2 to live or not
By the type of food they need
Classification: Shape
• Most bacteria are found in
groups rather than individual
cells. Large groups are called
colonies.
• Spherical (cocci, sin: coccus)
• Rod-shaped (bacilli, sin:
bacillus)
• Spiral (spirilla, sing: spirillus)
Classification: Gram Staining
• Bacteria have a polymer called peptidoglycan
in cell wall.
• Bacterial cell walls may react with a chemical
stain called Gram stain. If they do react, then
they are called “Gram-positive bacteria” (more
polymers = thick wall) and will be purple.
• If they don’t react, then they are called “Gramnegative bacteria” (less polymers = thin wall)
and will be pink.
Classification: Oxygen
• Aerobic bacteria need oxygen to live
– Eg. Tuberculosis bacteria
• Anaerobic bacteria do not need oxygen to live
– Eg. Gangrene, botulism, tetanus bacteria
• Most bacteria can live with or without oxygen,
such as E. coli.
Classification: Food
• Autotrophs – make own food using sunlight
(like plants)
• Chemosynthetic – make own food from
chemicals in their env. like methane)
• Heterotrophs – get food from consuming
other organisms, either living or dead  most
common type
Reproduction
• Reproduce asexually by
binary fission
– Parent cell begins to divide
– Cell doubles its cytoplasm & cell
wall making enough for 2 cells. It
replicates its DNA (exact copy)
– When cell has doubled all of its
components, a cross-wall is
formed. Parent cell begins to
pinch into two.
– Two daughter cells are formed.
They are exact copies of each
other and the parent cell.
Reproduction
• Some bacteria can reproduce sexually by conjugation
– Two different bacteria cells (one donor and one recipient) make
contact
– A sex pilus (tube) is formed
– One strand of a plasmid moves through pilus to the other cell.
– Recipient cell makes complimentary strand of plasmid, as well as
donor cell.
– Bacteria separate