They Are Everywhere
An introduction to bacteria
Prokaryotes
Prokaryote: Single-celled organism that
lacks a true nucleus (also called bacteria)
DNA is not surrounded by a nuclear
membrane, have no membrane bound
organelles.
 Cover almost every
cm2 of earth!

Size Matters
Prokaryotes = 1-5 micrometers
 Eukaryotes = 10-100 micrometers

Vs.
Prokaryotic cells are much
smaller than eukaryotic
cells.
One to Two
*Until recently all prokaryotes were one
kingdom, Monera
 Monera is now split into 2 kingdoms:
 Eubacteria, Archaebacteria

Now three domains
1)Eubacteria/Bacteria
2)Archaea
3)Eukaryota/Eukarya
Archaebacteria!
A hot springs in Yellowstone National park!
Archaeabacteria
Lack peptidoglycan walls and have
different membrane lipids than Eubacteria
 DNA sequences are closer to Eukaryotes
than Bacteria

Extremophiles –
‘phileo’ in Greek means love

Extremophiles:
– Live in extreme environments!
Halophilic: salt loving
Thermophilic: heat loving
Methanogens – produce methane gas
Live in the gut of
mammals,
sewage disposal
plants and swamps
Eubacteria
Largest of prokaryote groups
 *Have cell walls that contain
peptidoglycan (carbohydrate)
 Find everywhere on earth.

Shapes

Three Shapes
1) Bacilli
3) Spirilla
(rod-shaped)
(spiral or corkscrew)
2) Cocci
(spherical)
“Strep” throat
Shapes
Streptococci
Streptobacilli
Form chains or strings
Staphylococci
Staphylobacilli
Form clumps like grapes
Streptospirilla
SSSS
S
Staphylospirilla
Round = Cocci
Rod shaped =
Bacilli
Spiral shaped = spirilla
Ribosome
Flagella
Pili
Capsule
Cell wall
Cell membrane
DNA
Plasmid
Cytoplasm
Plasmid – piece of DNA ,
plays role during conjugation
Pili Help with
conjugation –
transferring
of genetic
material
p.558,
Stick
to host’s cells
Cytoplasm Contains DNA,
Proteins and
plasmid
Capsule – Protects against
drying out, chemicals and
host’s white blood cells.
Flagella:
Movement
Ribosomes- Making
proteins
Cell wall - Protects, gives
cell shape
Eubacteria–has peptidoglycan
DNA - Carries the
genetic material
Cell membrane –
Regulates the movement of materials
in and out of the cell
Conjugation
Pili – forming conjugation bridge
Cell Walls

Two Types of Eubacteria:
– Gram-Positive
 Thick peptidoglycan walls
 Turn dark purple when stained
– Gram-Negative
 Much thinner walls inside an outer lipid layer
 Appear pink or light red
Energy

Heterotrophs

Parasitic – Cause diseases (pathogens)

Saprophytic – Feed on dead tissues Decomposers
Autotrophs

Photoautotrophs:
– Use light energy to convert CO2 and H2O to
food (like plants)
– Ex: cyanobacteria

Chemoautotrophs:
– Use chemical energy to convert CO2 and H2O
to food
Releasing Energy

Obligate Aerobes:
– Require constant supply of oxygen

Obligate Anaerobes:
– Do not require oxygen . . . It kills them

Facultative Anaerobes:
– Do not require oxygen, but can live with it
– Ex: E. coli
*Growth and Reproduction

Some bacteria can divide every 20
minutes
– If there was unlimited resources 1 bacteria
could grow into a mass 4000 times the mass
of earth in just 48 hours!!!
Reproduction
Binary fission
1) Binary Fission

Binary Fission:
– Asexual reproduction where organism
replicates DNA and divides in half
– Produces two identical daughter cells
2) Conjugation
Conjugation: (“Sexual” reproduction)
A type of sexual reproduction where
organism exchange genetic information
3. Forming Endospores
• Help survive unfavorable conditions.
Anthrax spores
Some are BAD and make us ill
Streptococcus
Strep throat
Pneumonia
Tetanus (lock jaw)
Affects nervous
system
E. coli
Some in our
intestines …
others are
pathogens that
can cause kidney
failure
Bacteria
Can be bad … but can be good
Make vitamins that
we cannot make
ourselves
Decomposers

*Help breakdown sewage treatment water
Feel better with??
Nitrogen Fixation

Converting nitrogen gas into a form plants
can use (nitrates – NO3)
– Plants use the nitrates to make proteins.
For example Rhizobium
living in the roots of
legumes such as soybean
plants.
Other Uses
 Oil
digestion/
Clean up of pollutants
(Bioremediation)
Are living:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Made up of cells
Have DNA
Grow and develop
Use energy
Homeostasis
Reproduction
Respond to stimuli
Evolve/Show adaptations – resistant bacteria
Show some type of organization – Flagella,
pili, ribosomes, cell wall