Bacteria come in a variety of shapes and sizes. They can be spherical, spiral, or rod-shaped. Bacteria reproduce asexually through binary fission where a single parent cell divides into two identical daughter cells. Some bacteria can also undergo sexual reproduction through conjugation where DNA is transferred between two bacteria through a bridge. Bacteria have different ways of obtaining food including photosynthesis, breaking down chemicals, or consuming other organisms or organic matter. They can survive unfavorable conditions by forming hardy endospores. Bacteria play both helpful and harmful roles in nature such as producing oxygen, recycling nutrients, causing disease, and spoiling food.

1. Types of Microbes
BACTERIA

2. The Cell Structures
• Bacteria are PROKARYOTES = genetic
material is not contained in a nucleus.
• DNA in a bacteria cell is found floating in
the cytoplasm.
• A FLAGELLUM = a long whip-like
structure that helps a cell to move.
FLAGELLA = plural of FLAGELLUM
• A bacteria can have many flagella, one
flagellum, or no flagella.

3. Cell Shapes
The three basic shapes of bacteria are:
Sphere shaped
bacteria
Spiral shaped
bacteria
Rod shaped
bacteria

4. Cell Shapes
• The chemical make-up of the cell wall
determines the shape of a bacterial cell.
The shape helps Scientists identify the
type of bacteria.

5. Cell Sizes
The size of bacteria vary greatly:
The largest bacteria = as big as a period at
the end of a sentence.
Average bacteria = much smaller
They are usually measured in micrometers
(μm) or millionths of a meter.

6. OBTAINING FOOD AND ENERGY
All bacteria need the following to survive:
1. A source of food
2. A way of breaking down the food to
release energy.

7. Obtaining Food
•
•
Some bacteria are AUTOTROPHS
An AUTOTROPH = organisms that make
their own food.
Q: Are humans autotrophs?
• The 2 ways autotrophic bacteria make
food are:
1. Some capture and use the Sun’s energy to
make food
2. Some use the energy from chemicals in their
environment to make their food.

8. Obtaining Food
• A HETEROTROPH = organisms that
cannot make their own food.
Q: Are humans heterotrophs?
• Heterotrophic bacteria must consume
other organisms or the food that other
organisms make.

9. Respiration (remember this?)
• Respiration = the process of breaking
down food with the use of oxygen.
• All bacteria do not need oxygen. Some
use FERMENTATION! Do you
remember???

10. REPRODUCTION
Bacteria reproduce frequently when:
1. They have plenty of food
2. The right temperature
3. Other conditions (water, the right
chemicals)
• Under the best conditions (ideal) bacteria
can reproduce as often as once every 20
minutes.

11. Asexual Reproduction
• BINARY FISSION = the process of
reproduction in bacteria where 1 cell
divides to form 2 identical cells. It is a
type of ASEXUAL REPRODUCTION =
the reproductive process that involves only
1 parent and produces offspring that are
identical to the parent.

12. Asexual Reproduction
• Binary Fission (a type of Asexual
Reproduction) is just like CELL DIVISION,
what we studied not too long ago.
CELL DIVISION
For Animal and
Plant Cells
PARENT
BINARY FISSION
(a type of Asexual
Reproduction)
For Bacteria
2 DAUGHTERS

13. Sexual Reproduction
• SEXUAL REPRODUCTION = involves 2
parents who combine their DNA to
produce a new organism. The new
organism is different from both of the
parents.
• CONJUGATION = the process where 1
bacterium gives some of its DNA into
another bacterium through a thread-like
bridge

14. CONJUGATION
Bacteria 1
THREAD-LIKE
BRIDGE
Bacteria 2
DNA
BEFORE

15. CONJUGATION
Bacteria 1
Bacteria 2
AFTER

16. Sexual Reproduction
1.Conjugation results in bacteria with new
combinations of DNA.
• Then, when the bacteria reproduce by
Binary Fission, the resulting daughter
bacteria have the new DNA in them.

17. Sexual Reproduction
2. Conjugation results in genetically different
bacteria cells, not an increase in the
number of bacteria cells.
• These NEW bacteria may be more fit to
survive than the parent bacteria.

18. Endospore Formation
Unfavorable conditions for bacteria growth
are:
1. No food
2. No water
3. A huge change in temperature

19. Endospore Formation
• An ENDOSPORE = a small, rounded,
thick-walled resting cell that forms inside a
bacterial cell. It contains the DNA and
some cytoplasm
Endospore

20. Endospore Formation
• The formation of an Endospore allows the
bacterium to stay alive in terrible
conditions for years. Once the terrible
conditions get better, the bacterium can
begin to grow and reproduce again.
• Its kind of like HIBERNATION.

21. THE ROLE OF BACTERIA IN
NATURE
GOOD THINGS BACTERIA DO:
1. Make Oxygen
2. Make Food
3. Environmental recycling & clean-up
4. Health & Medicine

22. THE ROLE OF BACTERIA IN
NATURE
BAD THINGS BACTERIA DO:
1. Cause disease
2. Spoil Food – waste money