Bacteria are single-celled organisms that come in three main shapes - bacilli (rod-shaped), cocci (spherical), and spirilla (spiral-shaped). A single gram of soil contains over 2.5 billion bacteria, and there are more types of bacteria on Earth than all other living things combined. Bacteria reproduce through binary fission and do not have nuclei like eukaryotic cells. The two main kingdoms of bacteria are Eubacteria and Archaebacteria, which contain the oldest forms of life and inhabit a variety of extreme environments.

2. Guess how manyGuess how many
bacteria are in a singlebacteria are in a single
handful of soil?handful of soil?
A singleA single gramgram of soil (theof soil (the
size of a pencil eraser)size of a pencil eraser)
has 2.5 billion bacteria,has 2.5 billion bacteria,
so a handful wouldso a handful would
containcontain trillionstrillions!!
There are more types ofThere are more types of
bacteria on Earth than allbacteria on Earth than all
other living thingsother living things
combinedcombined

3. Most bacteria are tooMost bacteria are too
small to see without asmall to see without a
microscopemicroscope
The largest knownThe largest known
bacteria are 1,000bacteria are 1,000
times larger than thetimes larger than the
average bacteriumaverage bacterium
One of these giantOne of these giant
bacteria lives inside abacteria lives inside a
surgeonfish—it is 0.6surgeonfish—it is 0.6
mm long and can bemm long and can be
seen with the nakedseen with the naked
eyeeye

4. Characteristics ofCharacteristics of
BacteriaBacteria
Bacteria make up theBacteria make up the
kingdomskingdoms Eubacteria andEubacteria and
ArchaebacteriaArchaebacteria
These two kingdoms containThese two kingdoms contain
the oldest forms of life onthe oldest forms of life on
EarthEarth
All bacteria areAll bacteria are singlesingle-celled-celled
organismsorganisms
Bacteria are usually one ofBacteria are usually one of
threethree main shapes: bacilli,main shapes: bacilli,
cocci, or spirillacocci, or spirilla

5. The Shape of BacteriaThe Shape of Bacteria
Most bacteria have a rigidMost bacteria have a rigid
cell wallcell wall that gives them theirthat gives them their
shapeshape
EachEach shapeshape of bacteriaof bacteria
helps it in a different wayhelps it in a different way
Some bacteria haveSome bacteria have hairlikehairlike
parts, called flagella, whichparts, called flagella, which
spin and help push aspin and help push a
bacterium through water orbacterium through water or
other liquidsother liquids

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

7. BacilliBacilli
– Rod shapedRod shaped
– Large surface area (take in nutrientsLarge surface area (take in nutrients
quickly, but dry out easilyquickly, but dry out easily
CocciCocci
– SphericalSpherical
– Do notDo not dry outdry out as quickly as bacillias quickly as bacilli
SpirillaSpirilla
– Use flagella at both ends to move like aUse flagella at both ends to move like a
corkscrewcorkscrew

8. No Nucleus!No Nucleus!
All bacteria areAll bacteria are
single-celled and dosingle-celled and do
not have anot have a nucleusnucleus
This makes bacteria aThis makes bacteria a
prokaryoteprokaryote
Prokaryotes functionProkaryotes function
asas independentindependent
organismsorganisms
ProkaryotesProkaryotes
reproduce differentlyreproduce differently
than eukaryotes dothan eukaryotes do

9. Bacterial ReproductionBacterial Reproduction
Bacteria reproduce by processBacteria reproduce by process
ofof binary fissionbinary fission
Binary fission: a form ofBinary fission: a form of asexualasexual
reproduction in a single-celledreproduction in a single-celled
organism by which one cellorganism by which one cell
divides into two cells of thedivides into two cells of the
same sizesame size
No nucleus, so DNA is just aNo nucleus, so DNA is just a
circularcircular looploop with no membranewith no membrane

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

11. EndosporesEndospores
Most species of bacteria do well inMost species of bacteria do well in warmwarm,,
moist placesmoist places
In cold or dry surroundings, the bacteriaIn cold or dry surroundings, the bacteria
will eitherwill either diedie or become inactive and formor become inactive and form
endosporesendospores
EndosporesEndospores: contains: contains geneticgenetic materialmaterial
and proteins and is covered by a thick,and proteins and is covered by a thick,
protectiveprotective coatcoat

12. Many endosporesMany endospores
survive in cold, hot,survive in cold, hot,
and very dryand very dry
placesplaces
When conditionsWhen conditions
improve, theimprove, the
endosporesendospores breakbreak
openopen, and the, and the
bacteria becomebacteria become
activeactive againagain

13. Scientists foundScientists found
endospores inside anendospores inside an
insect that wasinsect that was
preserved inpreserved in amberamber
for 30 million yearsfor 30 million years
When the endosporesWhen the endospores
were moistened in awere moistened in a
lab, bacteria began tolab, bacteria began to
grow!grow!

14. Kingdom EubacteriaKingdom Eubacteria
Eubacteria are classified by the way theyEubacteria are classified by the way they
get theirget their foodfood
Most areMost are consumersconsumers, which get food by, which get food by
eating othereating other organismsorganisms
Many bacteria areMany bacteria are decomposersdecomposers, which, which
feed onfeed on deaddead organismsorganisms
Eubacteria that make their food areEubacteria that make their food are
producersproducers (use energy from sunlight to(use energy from sunlight to
make own food, oftenmake own food, often greengreen))

15. CyanobacteriaCyanobacteria
–Are producersAre producers
–Usually live inUsually live in
waterwater
–Contain greenContain green
pigmentpigment
chlorophyllchlorophyll
–Some have aSome have a
blue tint thatblue tint that
helps inhelps in
photosynthesisphotosynthesis

16. OtherOther
cyanobacteriacyanobacteria
have a redhave a red
pigmentpigment
Flamingos getFlamingos get
theirtheir pinkpink colorcolor
from eating redfrom eating red
cyanobacteriacyanobacteria

17. Kingdom ArchaebacteriaKingdom Archaebacteria
Three main types of Archaebacteria: heatThree main types of Archaebacteria: heat
lovers,lovers, saltsalt lovers, andlovers, and methanemethane makersmakers
Heat loversHeat lovers
– Live in oceanLive in ocean ventsvents and hot springsand hot springs
– Live in very hot water, can survive temps of moreLive in very hot water, can survive temps of more
than 250 degrees Celsiusthan 250 degrees Celsius
Salt loversSalt lovers
– Live in environments of high salt, like the Dead SeaLive in environments of high salt, like the Dead Sea
and Great Salt Lakeand Great Salt Lake
Methane makersMethane makers
– Give off methaneGive off methane gasgas and live inand live in swampsswamps and animaland animal
intestinesintestines

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

19. Harsh environmentsHarsh environments
– Archaebacteria oftenArchaebacteria often
live where nothing elselive where nothing else
cancan
– Most preferMost prefer
environment with littleenvironment with little
to noto no oxygenoxygen
– Very different fromVery different from
eubacteriaeubacteria
– Not all archaebacteriaNot all archaebacteria
havehave cell wallscell walls
– When they do, the cellWhen they do, the cell
walls are chemicallywalls are chemically
different fromdifferent from
eubacteriaeubacteria