PROKARYOTES
I. Characteristics of Prokaryotes
1.NO NUCLEUS
2.Organized by their need for oxygen.
a) Obligate anaerobe -dies in the presence of
oxygen
b) Obligate aerobes -need oxygen
c) Facultative aerobes- doesn’t need oxygen,
but oxygen wont kill it.
I. Characteristics of Prokaryotes
3. Prokaryotes are classified by their shape.
Bacillus- rod shaped
Coccus- sphere
shaped
Spirillius- spiral
shape
I. Characteristics of Prokaryotes
4. Prokaryotes may group together
a) diplo- groups of 2
b) strepto- chains
c) staphylo- grapelike clusters.
Names are based on shape & grouping
•What is this prokaryotes name?
Names are based on shape & grouping
•What is this prokaryotes name?
Streptococcus
II. Structure of Prokaryotes
1. Microscopic b/c unicellular
2. No Nucleus, No membrane bound organelles
3. Contains protein making ribosomes.
4. Single, circular chromosome in ‘nucleoid
region’
II. Structure of Prokaryotes
5. Plasmids- DNA fragments in cytoplasm
6. Cell wall –protection/support, made of
peptidoglycan
7. flagella/cilia- movement (1 many flagella)
8. May have a sticky coating called a capsule for
attachment to host cells or other bacteria.
III. Types of Prokaryotes
1. Archaea
a)
b)
c)
d)
Most ancient/primitive type of bacteria.
Live in very harsh environments
Have NO peptidoglycan in it’s cell wall
Gram negative
2. Eubacteria
a) Most numerous bacteria on earth.
b) Most likely to encounter eubacteria
c) LOTS of peptidoglycan in cell wall
d) Gram positive
IV. Variety in Prokaryotes
• Photoautotroph-near surface to receive sunlight
• chemoautotroph- make food from chemicals; found in oceans around
hydrothermal vents
• Nitrogen fixing- converts N gas into nitrates, a form of N plants can
use.
• Halophiles – live in extremely salty environments
• Thermophiles- live in extremely hot or cold environments
• Decomposers-break down dead stuff
• Methanogens- digestive tract of animals.
IV. Variety in Prokaryotes
Chemoautotrophs-A
Halophiles-A
IV. Variety in Prokaryotes
Thermoacidophiles-A
Nitrogen Fixing-E
IV. Variety in
Prokaryotes
Methanogens(Archaea):
create
methane as a
byproduct.
V. Reproduction/Survival Methods
• Binary fission- asexual reproduction, 2 identical
cells.
• Conjugation- DNA is exchanged through a pili
connecting bridge.
• Endospore- protective coat that allows for their
survival in unfavorable conditions (lies dormant
until conditions are favorable again.)
Binary
Fission
VI. How do Bacteria help us?
1. Symbiotic relationships: E coli in intestinal tract makes vitamin k for
us.
2. Fermentaion: produces yogurt, cheese, pickles, soy sauce.
3. Decomposers: putting N, c, H, H back into the soil for use by
another organism.
4. Bioremediation-using bacteria to clean oil spills and other
pollutants.
5. Making of drugs- insulin is produced in a lab via manipulating the
DNA of common bacterium.
VII. How do bacteria harm us?
•Some prokaryotes release toxins
that destroy cells. As prokaryotes
reproduce quickly, the toxin builds
up in the body until the organism
becomes sick overall.
VIII. How to prevent bacteria infections?
•Antibiotics: break down bacterial cell walls.
•Store and cook meats correctly.
•Keeps hands clean and away from your face.
(eyes, nose and mouth are easy places for
bacteria to enter you.)
Note about antibiotics:
• Overuse of antibiotics leads to bacterial resistance of
the antibiotic.
• Plasmids are easily mutated then shared via conjugation.
• Leads to generations of bacteria which are no longer killed
by the antibiotic.
• Only use antibiotics when absolutely necessary.
IX. How do you know which bacteria has made
you sick and what treatment to pursue?
• Gram Staining will help identify which type of
bacteria has infected you and what course of
treatment will rid you of them.
• Bacteria are treated with purple Crystal Violet and red
Safranin stains.
• Cell walls will either stain purple or reddish pink
depending on the composition of the cell wall.
Gram Staining and Cell Walls
Gram Positive (+) bacterium
Gram Negative (-) bacterium
Gram
Positive (+)
•Have a THICK layer of
peptidoglycan in cell
wall.
•Peptidoglycan absorbs
the purple dye easily.
•CAN be treated with
antibiotics.
Gram
Negative (-)
• Have THIN layer of
peptidoglycan in cell wall.
• Purple stain is not
absorbed, red Safranin is.
• Cell wall with turn pink.
• Much harder to treat with
antibiotics.