There are more bacteria on Earth than all other living things combined. Bacteria come in three main shapes - bacilli, cocci, and spirilla - which help them in different ways. All bacteria are single-celled prokaryotes that reproduce through binary fission and do not have nuclei. Some bacteria form protective endospores that allow them to survive in harsh environments. The two kingdoms of bacteria are Eubacteria and Archaebacteria, which contain the oldest and most diverse forms of life and can be found in extreme habitats.

2. Guess how many
bacteria are in a single
handful of soil?
A single gram of soil (the
size of a pencil eraser)
has 2.5 billion bacteria,
so a handful would
contain trillions!
There are more types of
bacteria on Earth than all
other living things
combined

3. Most bacteria are too
small to see without a
microscope
The largest known
bacteria are 1,000
times larger than the
average bacterium
One of these giant
bacteria lives inside a
surgeonfish—it is 0.6
mm long and can be
seen with the naked
eye

4. Characteristics of
Bacteria
Bacteria make up the
kingdoms Eubacteria and
Archaebacteria
These two kingdoms contain
the oldest forms of life on
Earth
All bacteria are single-celled
organisms
Bacteria are usually one of
three main shapes: bacilli,
cocci, or spirilla

5. The Shape of Bacteria
Most bacteria have a rigid
cell wall that gives them their
shape
Each shape of bacteria
helps it in a different way
Some bacteria have hairlike
parts, called flagella, which
spin and help push a
bacterium through water or
other liquids

6. Cocci (spherical)
Bacilli (rod shaped)
Spirilla (long and spiral shaped)

7. Bacilli
– Rod shaped
– Large surface area (take in nutrients
quickly, but dry out easily
Cocci
– Spherical
– Do not dry out as quickly as bacilli
Spirilla
– Use flagella at both ends to move like a
corkscrew

8. No Nucleus!
All bacteria are
single-celled and do
not have a nucleus
This makes bacteria a
prokaryote
Prokaryotes function
as independent
organisms
Prokaryotes
reproduce differently
than eukaryotes do

9. Bacterial Reproduction
Bacteria reproduce by process
of binary fission
Binary fission: a form of asexual
reproduction in a single-celled
organism by which one cell
divides into two cells of the
same size
No nucleus, so DNA is just a
circular loop with no membrane

10. DNA is copied, loops separate
New cell wall forms and
cells separate

11. Endospores
Most species of bacteria do well in warm,
moist places
In cold or dry surroundings, the bacteria
will either die or become inactive and form
endospores
Endospores: contains genetic material
and proteins and is covered by a thick,
protective coat

12. Many endospores
survive in cold, hot,
and very dry
places
When conditions
improve, the
endospores break
open, and the
bacteria become
active again

13. Scientists found
endospores inside an
insect that was
preserved in amber
for 30 million years
When the endospores
were moistened in a
lab, bacteria began to
grow!

14. Kingdom Eubacteria
Eubacteria are classified by the way they
get their food
Most are consumers, which get food by
eating other organisms
Many bacteria are decomposers, which
feed on dead organisms
Eubacteria that make their food are
producers (use energy from sunlight to
make own food, often green)

15. Cyanobacteria
– Are producers
– Usually live in
water
– Contain green
pigment
chlorophyll
– Some have a
blue tint that
helps in
photosynthesis

16. Other
cyanobacteria
have a red
pigment
Flamingos get
their pink color
from eating red
cyanobacteria

17. Kingdom Archaebacteria
Three main types of Archaebacteria: heat
lovers, salt lovers, and methane makers
Heat lovers
– Live in ocean vents and hot springs
– Live in very hot water, can survive temps of more
than 250 degrees Celsius
Salt lovers
– Live in environments of high salt, like the Dead Sea
and Great Salt Lake
Methane makers
– Give off methane gas and live in swamps and animal
intestines

18. Heat lovers in ocean vent
Salt lovers in Dead Sea
Methane makers in swamp

19. Harsh environments
– Archaebacteria often
live where nothing else
can
– Most prefer
environment with little
to no oxygen
– Very different from
eubacteria
– Not all archaebacteria
have cell walls
– When they do, the cell
walls are chemically
different from
eubacteria