Dyzza Lei L. Albarico
Julian Philip A. Soriano
Shaina Mavreen D. Villaroza
What are Prokaryotic Cells?
Prokaryotes are single-celled organisms that are
the earliest and most primitive forms of life on
They have no true nucleus as the DNA is not
contained within a membrane or separated from
the rest of the cell
Prokaryotes do not have a
nucleus, mitochondria, or any other membrane-
bound organelles. In other words, neither their
DNA nor any of their other sites of metabolic
activity are collected together in a discrete
They have a single, circular chromosome.
They have cell walls containing peptidoglycan
Their DNA is not associated with Histones.
Capsule - Found in some bacterial cells, this
additional outer covering protects the cell
when it is engulfed by other organisms, assists
in retaining moisture, and helps the cell
adhere to surfaces and nutrients.
Cell Wall - Outer covering of most cells that
protects the bacterial cell and gives it shape.
Cytoplasm - A gel-like substance composed
mainly of water that also contains
enzymes, salts, cell components, and various
Cell Membrane or Plasma
Membrane - Surrounds the cell's
cytoplasm and regulates the flow of
substances in and out of the cell.
Pili - Hair-like structures on the
surface of the cell that attach to other
bacterial cells. Shorter pili called
fimbriae help bacteria attach to
Flagella - Long, whip-like protrusion
that aids in cellular locomotion.
Ribosomes - Cell structures
responsible for protein production.
Plasmids - Gene carrying, circular
DNA structures that are not involved in
Nucleiod Region - Area of the
Prokaryotes appear in 3 basic shapes:
1. Coccus – Spherical shaped
2. Bacillus – Rod shaped (plural, Bacilli)
3. Spirillium – Spiral known
The cocci are spherical or oval bacteria
having one of several distinct arrangements
based on their planes of division.
a. Division in one plane produces either
a diplococcus or streptococcus
1. diplococcus: cocci arranged in pairs
2.streptococcus: cocci arranged in chains
b. Division in two planes produces
a tetrad arrangement.
1.a tetrad: cocci arranged in squares of 4
c. Division in three planes produces
a sarcina arrangement.
1.sarcina: cocci in arranged cubes of 8
d. Division in random planes produces
a staphylococcus arrangement.
1.staphylococcus: cocci arranged in
irregular, often grape-like clusters
An average coccus is about 0.5-1.0 micrometer
(µm) in diameter.
(A micrometer equals 1/1,000,000 of a meter.)
Spirals come in one of
three forms, a vibrio, a spirillum, or
a) vibrio: a curved or comma-shaped rod
b) spirillum: a thick, rigid spiral
c) spirochete: a thin, flexible spiral
Spirals range in size from 1 µm to over
100 µm in length.
Bacilli are rod-shaped bacteria. Bacilli all
divide in one plane producing
a bacillus, streptobacillus, or coccobacillus ar
a) bacillus: single bacilli
b) streptobacillus: bacilli arranged in chains
c) coccobacillus: oval and similar to a coccus
An average bacillus is 0.5-1.0 µm wide by
1.0-4.0 µm long.
Staining can be performed with basic
dyes such as crystal violet or
methylene blue, positively charged
dyes that are attracted to the
negatively charged materials of the
This differential technique separates bacteria into
two groups, Gram-positive bacteria and Gram-negative
Crystal violet is first applied, followed by the
mordant iodine, which fixes the stain .Then the slide is
washed with alcohol, and the Gram-positive bacteria
retain the crystal-violet iodine stain; however, the Gram-
negative bacteria lose the stain.
The Gram-negative bacteria subsequently stain
with the safranin dye, the counterstain, used next.
These bacteria appear red under the oil-immersion
lens, while Gram-positive bacteria appear blue or
purple, reflecting the crystal violet retained during the
Figure 1. The Gram stain
procedure used for differentiating
bacteria into two groups.
•Acid Fast Stain
This technique differentiates species
of Mycobacterium from other bacteria.
Heat or a lipid solvent is used to carry the first
stain, carbolfuchsin, into the cells. Then the cells are
washed with a dilute acid-alcohol
solution. Mycobacterium species resist the effect of the
acid-alcohol and retain the carbolfuchsin stain (bright
Other bacteria lose the stain and take on the
subsequent methylene blue stain (blue). Thus, the acid-
fast bacteria appear bright red, while the nonacid-fast
bacteria appear blue when observed under oil-
Negative Staining for Capsule
Capsule staining uses a mixture of the bacteria
in a solution containing a fine colloidal
suspension of colored particles to provide a dark
background and then stain the bacteria with a
simple stain such as safranin.
◦ An endospore is a special resistant
dormant structure formed within a cell that
protects a bacterium from adverse
environmental conditions. Endospores
cannot be stained by ordinary methods
such as simple stains and gram staining.
Malachite green the primary stain is
applied to a heat fixed smear and heated
to steaming for about 5 min. Then the
perparation is washed for about 3o sec.
with water to remove the malachite green
from all the cells parts except for the
A tedious and delicate staining
procedure uses a mordant and the stain
carbolfuchsin to build up the diameters of
the flagella until they become visible
under the light microscope