Bacteria are microscopic single-celled organisms that lack a nucleus and organelles. They reproduce through binary fission and have a cell wall, cell membrane, and cytoplasm. Bacteria come in various shapes (cocci, bacilli, spirals) and sizes from 0.5-5.0 μm. Structures include flagella, pili, spores and inclusions. Bacteria can be helpful in digestion and decomposition or harmful as pathogens. Overall, bacteria are simple prokaryotic cells that are found nearly everywhere and impact many life processes.

1. General Microbiology
Structure & Function

2.  Morphology (in biology) - study of the size, shape,
and structure of microorganisms and of the
relationships of the parts comprising them.
 Aerobic bacteria: those that need oxygen in order
to live and grow.
 Anaerobic bacteria: those that don’t require
oxygen in order to live.
 Pasteurization: A process by which bacteria in
food are killed by heating the food to a particular
temperature for some given period of time.
 Decomposers: Bacteria that break down dead
organic matter.

3.  Binary Fission – is the primary method of a
procaryotic organism. It is the separation of the
body into two new bodies. In the process, an
organism duplicates its genetic material (DNA), and
then divides into two parts (cytokinesis), with each
new organism receives 1 copy of DNA.

4. INTERESTING FACTS

5. All of bacteria in our body collectively weighs about 4 lbs.
There are more bacteria in mouth than people in the world
The “smell of rain” is caused by a bacteria called
ACTINOMYCETES
Sweat itself is odorless. It’s the bacteria that
mingles with it that causes body odor.
Chocolate has anti-bacterial effect on the mouth and
protects against tooth decay.
Most antibiotics are made from bacteria
Tap water has a shelf-life of 6months, after chlorine
dissipates, bacteria starts to grow

6. The strongest creatures on earth are gonorrhea bacteria.
They can pull 100,000 time their own body weight.
Earwax has antimicrobial properties that reduce the
viability of bacteria & fungus in the human ear.
Honey is a natural reservoir for Botulism bacteria. Adults
can normally process it and infants can’t and this is why
you shouldn’t give babies honey.
Unwashed eggs still have their protective coating, the bloom, and are safe
to store on the counter. Many modern countries wash eggs before sale
so they ‘look’ cleaner and safer, but this opens the pores of the shell for
infection from bacteria during storage time.
Human poop, by weight, is mostly bacteria that are
both dead and alive.

7. Human bites are one of the most dangerous animal bites
in the world due to the bacteria in our mouths
A group of scientists transcribed the song “It’s a Small World After All”
into the DNA of a bacteria that is resistant to radioactivity, so that in
the event of a nuclear catastrophe, we could pass a message on to
future intelligent life
A specie called Deinococcus radiodurans, can survive
almost 10,000 x the dose of radiation lethal to humans
E. coli an travel 25 times their own length in 1 second,
equivalent to a horse running 135 miles per hour.
Australian scientists found that a bacterium called Ralstonia
metallidurans can turn dissolved gold into solid nuggets.

8.  much smaller and simpler
than eukaryotes
 they lack a true nucleus and
don’t have membrane bound
organelles.
 It’s DNA is found in it’s
central part called nucleoid.
 It’s cell wall acts as an extra
layer of protection, helps
maintain cell shape, and
prevents dehydration.

9.  Cell division by bacteria
 Asexual reproduction
 Fission- the act of cleaving or
splitting into parts.
 Binary fission results in two identical
daughter cells.

10. The cell wall prepares for replication.
The cell wall starts to rupture.

11. The cell makes a copy of its single,
circular chromosome.

12. The cell grows larger and the chromosomes
separate and move to opposite poles of the cell.
The cell membrane begins to pinch inward,
separating the two identical chromosomes.

13. Cytokinesis occurs and two identical
bacterium exist.

15.  Singular 'bacterium.‘
 Microscopic single-cell (unicellular) life form that exists
practically everywhere
 The smallest prokaryotic cell
 Visible only with the aid of a microscope
 It has peptidoglycan cell wall which protects it from
environtment with extreme temperatures.

16.  Bacteria are measured in units of length called
micrometers, or microns.
1 mm = 1,000 microns
 The small size of prokaryotes allows quick entry in an
organism.
 Coccus = 0.5 to 1.0 µm
 Bacilli = 0.5 to 1.0 µm in breadth; 1.0 to 4.0 µm in length.
 Spiral bacteria - 1.0 µm to over 100.0 µm in length
 Star-shaped, filamentous, and lobed commonly fall into a size range
of 1.0 µm

17.  Cocci – spherical/ oval shaped (major groups)
 Bacilli – rod shaped
 Spiral – rigid curved/coiled forms
 Filamentous – flexible slender forms
 Appendages – there is a part that is link/adjoin
 Box-shaped
 Star-shaped
 Vibrio – curved rodlike; motile
 Spirochete - spiral-shaped, most are serious
pathogens for humans

18. Spherical Rod-shaped Spiral shaped
“COCCI” are round
cells, sometimes
slightly flattened when
they are adjacent to
one another.
are curved bacteria
which can range from
a gently curved shape
to a corkscrew-like
spiral.
“BACILLI”

19. Filamentous Appendage Box-shaped
This allow bacteria to
have more surface
area for long-term
attachments and can
link themselves with
porous surfaces.
sensing environment,
defense against predators,
swimming, walking,
grasping, transferring
sperm, generating water
movement, and in gas
exchange.

20. Vibrio
Spirochetes
Star-shaped

22. COCCI
Staphylococci StreptococciDiplococci
The cocci are
arranged in
cluster
The cocci are
arranged in
pairs.
The cocci are
arranged in chains
Micrococcus are single

23. COCCI
SarcinaeTetrads
groups of four groups of eight

24. BACILLI
Square-ends
Diplobacilli Coccobacilli Streptobacilli
Club-shaped

25. BACILLI
Rounded-ends Fusiform

27. Outer layer - two components:
1. Rigid cell wall
2. Cytoplasmic (Cell/
Plasma) membrane –
present beneath cell
wall
Cytoplasm - gel-like substance enclosed within the cell
membrane. It contains cytoplasmic inclusions,
ribosomes, mesosomes and nucleoid.
Additional structures - plasmid, slime layer, capsule,
flagella, fimbriae (pili), spores

29. Appendages - flagella, pili or fimbriae
Surface layers - capsule, cell wall, cell membrane
Cytoplasm - nuclear material, ribosome, mesosome,
inclusions etc.
Special structure - endospore

31. Essential structures
cell wall
cell membrane
cytoplasm
nucleoid
Particular structures
capsule
flagella
pili

32. Cell wall
a rigid cell wall composed of
peptidoglycan, a protein-
sugar (polysaccharide)
molecule
Composed of : N-acetyl glucosamine
(NAG) & N-acetyl muramic acid (NAM)
alternating in chains, held by peptide
chains.
Chemical nature of the cell wall helps to divide bacteria into
two broad groups – Gram positive & Gram negative
Gram +ve bacteria have simpler chemical nature than Gram –
ve bacteria.

34.  The wall gives the cell its shape and surrounds the
cytoplasmic membrane, protecting it from the environment.
 Countering the effects of osmotic pressure
The strength of the wall is responsible for keeping the cell from bursting when there are
large differences in osmotic pressure between the cytoplasm and the environment.
 Providing attachment sites for bacteriophages. bacteriophages -
a virus that is parasitic (reproduces itself) in bacteria
 Providing a rigid platform for surface appendages- flagella,
fimbriae, and pili
 control permeability

35.  When bacteria are treated with antibiotics that interfere with
biosynthesis of peptidoglycan, wall-less bacteria are often
produced.
 Usually these treatments generate non-viable organisms. Wall-
less bacteria that can not replicate are referred to as spheroplast.

36.  Thin layer that separates cell wall
from cytoplasm
 Acts as a semipermeable
membrane: controls the inflow and
outflow of metabolites
 Composed of lipoproteins with
small amounts of carbohydrates
 Membranes are also dynamic,
constantly adapting to different
conditions.

37. Cytoplasmic membrane

38.  Colloidal system of variety of
organic & inorganic solutes in
viscous watery solution
• Contains:
ribosomes,
mesosomes,
inclusions
vacuoles
 Composed of lipoproteins with
small amounts of carbohydrates
 Membranes are also dynamic,
constantly adapting to different
conditions.

39. It is where the functions for cell growth, metabolism, and
replication are carried out
It is a gel-like matrix composed of water, enzymes,
nutrients, wastes, and gases and contains cell structures such as
ribosomes, a chromosome, and plasmids.

40.  Ribosomes - are
microscopic "factories“.
It is where protein synthesis
occur.
They translate the genetic code from
the molecular language of nucleic acid
to that of amino acids—the building
blocks of proteins.)
 Proteins are the molecules that
perform all the functions of cells
and living organisms.

41.  Mesosomes –
1. Principal sites of respiratory
enzymes.
The major function is to
increase the surface area of
the plasma membrane to
mainly help the cell to carry out
cellular respiration more
efficiently.

42.  Intracytoplasmic
inclusions
normally involved in storing
energy reserves or building
blocks for the cell.

43. These are structures surrounding the outside of the
cell envelope. They usually consist of polysaccharide; but
in certain bacilli they are composed of a polypeptide
(polyglutamic acid).
For:
 Attachment
 Protection from phagocytic
engulfment.
 Resistance to drying.
 Depot for waste products.
 Reservoir for certain
nutrients.

44.  The nucleoid is the region in
the prokaryotic cell that contains
the main DNA material.

45.  Extrachromosomal genetic material that also has DNA
 molecules。They are capable of self-replication and
contain genes that confer some properties，such as
antibiotic resistance.

46. are pigment-containing and light-reflecting cells
Only in photosynthetic bacteria and blue green algae.

47. For:
 Locomotion
 Rapid swimming or
movement caused by the
rotation
• attach to the cell by hook and
basal body which consists of
sets of rings and rods

48. Functions:
Chemotaxis: movement of bacteria toward or away from chemical
stimuli
Magnetotaxis: movement along the Earth's magnetic field.
Phototaxis: response to differences in light
density. Bacteria swim to areas of particular light intensities.

49. Types of distribution:
Monotrichous flagella: one flagellum, if it originates from one end
of the cell, it is called polar flagellum. Rapid swimming caused by the
rotation of flagella.
Peritrichous flagella: flagella surround the cell. Bundled
peritrichous flagella give rise to slower forward motion than polar flagella.

51.  Short, thin, straight, hairlike
projections form surface of some
bacteria. Composed of protein pilin,
carbohydrate and phosphate.
 They are known to be receptors for
certain bacterial viruses.
 Take part in adhesion of pathogen
to specific host tissues. Sex pili are
involved in genetic material
exchange between mating bacterial
cells.

52. 5. Spores :
• Highly resistant
resting stages formed
during adverse
environment (depletion of
nutrients)
• Formed inside the parent
cell, hence called
Endospores
• Very resistant to heat,
radiation and drying and
can remain dormant for
hundreds of years.

54.  Helpful bacteria.
Bacteria make possible the
digestion of foods in many
kinds of animals.
- In humans, bacteria known as Escherichia coli (E.
coli ) occur everywhere in the digestive system,
aiding in the breakdown of many kinds of foods.
Bacteria are also responsible
for the production of vitamin
K and certain B vitamins.
Certain kinds of bacteria are
also essential in the decay and
decomposition of waste
materials.
Some bacteria are involved in
the production of many foods
eaten humans.

55.  Harmful bacteria.
Pathogenic bacteria cause great diseases to animal and plant
life. Examples are: cholera, typhoid, pneumonia, dysentery,
tuberculosis, tetanus, etc.,
Bacteria also attack organisms by releasing
chemicals that are poisonous to plants and
animals. Such poisons are known as toxins.
Some saprophytic bacteria
grow on unprotected
foodstuffs and results to food
spoilage
Denitrifying bacteria affects the
fertility of the soil by reducing
nitrogen which goes to the
atmosphere.