Download BACTERIA CLASSIFICATION DOMAIN ARCHAEA DOMAIN

CLASSIFICATION
BACTERIA
The Oldest Living Structures
on The Earth
DOMAIN ARCHAEA
• Most inhabit extreme environments on the
earth. There are THREE main groupings.
• Methanogens – are anaerobic and live in
swamps, marshes, the gut of animals and
sewage treatment ponds
• Extreme Halophiles – live in high salt areas
such as the Dead Sea and Great Salt Lake
• Extreme Thermophiles – live in hot springs
with temperatures of 60 to 80 celsius.
• Living things can be
grouped in THREE
domains.
• Prokaryotes account
for two of the
domains.
• Eukaryota are all
eukaryotic organisms
DOMAIN BACTERIA
• Bacteria account for most prokaryotes.
• Includes the spirochetes, gram-positive
bacteria and cyanobacteria.
• These are the bacteria that we will
concentrate upon this year.
1
Size Relationships
DOMAIN COMPARISON
Micron
BACTERIA ARCHAEA EUKARYA
Nuclear
Envelope
Membrane
Organelles
Peptoglycan
Cell Wall
Ribosomes
Virus (.05 – 1 micron)
Absent
Absent
Present
Absent
Absent
Present
Red blood cell (5 microns)
Present
Absent
Absent
White blood cell (5 – 8
Present
Present
Present
Bacteria (.5 – 1.5 microns)
microns)
Sperm (60 microns)
Bacterial Shapes
• Bacillus bacteria are rod shaped.
• Cocci bacteria are round.
Identification
Gram Stain
The Gram stain differentiates bacteria on the basis of
structure and composition of the layers of the cell wall.
Upon completing the stain, Gram positive bacteria appear
purple and Gram negative bacteria appear pink. Gram
positive cell walls have a simpler structure than Gram
negative cell walls. Also note the shapes of bacteria
represented here.
•Spirillum are spiral shaped
2
General Structure
• Nearly all prokaryotes
have cell walls
• Bacteria have one major
chromosome and rings
of DNA called plasmids.
• Ribosomes are present to
help in protein
formation.
• Many disease causing
bacteria have a thick
outer slime capsule for
protection.
• Many bacteria have
small hair-like pili to
attach to other cells.
Bacterial Motility
Bacterial Cell Structure
• The CELLS ALIVE site will teach you about bacterial
cell structure. At the site click on Cell Models on the right
and when the page appears click on Bacteria to learn
more about the structures.
Bacterial Reproduction
• Prokaryotes reproduce asexually by binary
A motile E. coli propels itself from place to place by rotating its flagella.
To move forward,the flagella rotate counterclockwise and the organism
"swims". But when flagellar rotation abruptly changes to clockwise, the
bacterium "tumbles" in place and seems incapable of going anywhere.
Then the bacterium begins swimming again in some new, random
direction. Swimming is more frequent as the bacterium approaches a
chemoattractant (food). Tumbling, hence direction change, is more
frequent as the bacterium moves away from the chemoattractant. So it is
a complex combination of swimming and tumbling that keeps them in
areas of higher food concentrations.
fission thus making new DNA almost
continually .
• They can exchange genetic material in three
ways: transformation where genes are taken up
from the surrounding environment,
conjugation where genes are transferred from
cell to cell and transduction where genes are
transferred between prokaryotes by viruses.
3
Bacterial Population Growth
Bacterial Nutrition
• Photoautotrophs use
Click on the Cells Alive! icon and when you
reach that page scroll down to DIVIDING
BACTERIA. On viewing the dividing
bacteria take note of the FOUR stages of the
population growth curve.
the sun’s energy and
manufacture sugars.
• Chemoautotrophs
need only carbon
dioxide to obtain
energy from inorganic
substances.
Aerobic vs Anaerobic
• Obligate aerobes must
live where there is
oxygen present.
• Obligate anaerobes
must live where there
is no oxygen. They get
there energy through
fermentation.
• Facultative anaerobes
can live where there is
oxygen or no oxygen.
• Photoheterotrophs are
unique and use light to
generate energy but
must obtain but must
obtain carbon in
organic forms.
• Chemoheterotrophs
use organic molecules
such as sugar for
energy.
Not all bacteria are bad!!
• Many bacteria aid in the decomposition dead
•
•
•
•
•
•
organisms and waste.
Bacteria control the nitrogen cycle.
Bacteria is used to make cheese and yogurt.
Bacteria can be used to make antibiotics.
Bacteria are used to make sauerkraut.
Bacteria are used to clean up oil spills.
Bacteria are very useful in genetic engineering.
4
Food Bourne Bacteria
Can Harm You
Some of our more notorious food bourne
bacteria are botulinum, salmonella,
staphylococcus and E. coli. Clicking the icon
above will lead you to a site with information on
these bacteria.
Methods of Food Preservation
•
•
•
•
•
•
Freezing
Refrigeration
Pasteruization
Canning
Salting
Lactic acid
(sauerkraut)
• Vinegar
5