The document explores the morphology and classification of bacteria, detailing the differences between prokaryotic and eukaryotic cells, with a focus on their structures, reproduction, and biological functions. It also describes various types of bacteria based on shape and arrangement, microscopy techniques for studying bacteria, and staining methods to enhance visibility under a microscope. Overall, it provides a comprehensive overview of bacteria's biological characteristics and their role in the environment.

1. MORPHOLOGY AND
CLASSIFICATION OF BACTERIA
Prepared by:
Mona Alsadeg Alwash

2. INTRODUCTION
• Microbiology is the study
of the biology of
microscopic organisms -
viruses, bacteria, algae,
fungi, slime molds, and
protozoa. The methods
used to study and
manipulate these minute
and mostly unicellular
organisms differ from
those used in most other
biological investigations.

3. Prokaryotes
• Prokaryotes are organisms whose
cells lack a nucleus and other
organelles. Prokaryotes are
divided into two distinct groups:
the bacteria and the archaea,
which scientists believe have
unique evolutionary lineages.
• Most prokaryotes are small,
single-celled organisms that have
a relatively simple structure.
Prokaryotic cells are surrounded
by a plasma membrane, but they
have no internal membrane-bound
organelles within their cytoplasm.
The absence of a nucleus and
other membrane-bound organelles
differentiates prokaryotes from
another class of organisms called
eukaryotes.

4. A typical prokaryotic cell might contain th
following parts:
• Cell wall: the membrane
surrounding and protecting
the cell
• Cytoplasm: all of the material
inside a cell except the nucleus
• Flagella and pili: protein-based
filaments found on the outside
of some prokaryotic cells
• Nucleoid: a nucleus-like region
of the cell where genetic
material is kept
• Plasmid: a small molecule of
DNA that can reproduce
independently

5. Eukaryotics
• Eukaryotics or
eukarytic cell is acell
that contains
membrane-bound
structures, is the basis
for every multicellular
organism, including
animals, plants, and
humans as well as
some unicellular
organisms (organisms
with a single cell), such
as protozoa.

6. A typical eukaryotic cell
• is surrounded by a plasma membrane and contains many different
structures and organelles with a variety of functions. Examples
include the chromosomes (a structure of nucleic acids and protein
which carry genetic information in the form of genes.
• mitochondria (often described as the "powerhouse of the cell")
• Cell wall
• Ribosomes
• Flagella
• Cytoplasmic membrane
• lipids
• Lysosomes
• Golgi apparatus
• Endoplasmic Reticulum

7. How are prokaryotic and eukaryotic
cells similar?
• All prokaryotic and eukaryotic cells have some
similar features as they both contain ribosomes,
genetic material, a cytoplasm, and plasma
membranes.
• The cytoplasm is made up of cytosol, which is
the intracellular fluid in which the organic
material inside the cell is suspended and the
place where most cellular activity occurs.
• Plasma membranes protect the cell and allow for
transportation of materials in or out of the cells.

8. What is the difference between prokaryotic
and eukaryotic cells?
• nucleus and other membrane-bound
organelles are only present in eukaryotic
cells.
• Prokaryotes are always unicellular, while
eukaryotes are often multi-celled organisms.
Additionally, eukaryotic cells are more than 100
to 10,000 times larger than prokaryotic cells and
are much more complex.
• The DNA in eukaryotes is stored within the
nucleus, while DNA is stored in the cytoplasm of
prokaryotes.

9. • DNA in eukaryotic cells is stored in double-
stranded chromosomes that are condensed by
histones. In contrast, prokaryotic cells have
one primary circular chromosome and various
plasmids, which are small rings of DNA.
• The ribosomes in eukaryotic cells are 80S,
with 40S and 60S subunits, and in prokaryotic
cells: 70S with 30 and 50S subunits.

10. • In eukaryotic cells, flagella are microtubule
bundles composed of dynein and a plasma
membrane that is powered by ATP to make a
blending motion. Prokaryotic locomotive
structures are instead composed of repeated
flagellin, a hook, and a motor complex
attached to the cellular membrane that is
powered by protons to make a rotator motion.

11. • Prokaryotes can undergo binary, All eukaryotes
undergo a similar but more complicated process
called mitosis. In both binary fission and mitosis,
the parent cells have the exact same number of
chromosomes as their daughter cells.
• However, in sexually reproducing eukaryotic
organisms, they can also undergo meiosis during
which re-assortment creates genetically unique
reproductive cells called gametes or sex cells,
which have half the number of chromosomes as
the parent cells, so they are known as haploids.

13. BACTERIA
• Bacteria is unicellular, free-living,
microscopic microorganisms
capable of performing all the
essential functions of life. • They
possess both deoxyribonucleic
acid (DNA) and Ribonucleic acid
(RNA). • Bacteria are prokaryotic
microorganisms that do not
contain chlorophyll. • They occur
in water, soil, air, food, and all
natural environment. • They can
survive extremes of
temperature, pH, oxygen, and
atmospheric pressure.

14. SIZE OF BACTERIA
• Bacteria are very small microorganisms which
are visible under the microscope.
• They are having the size range in microns.
• Bacteria are stained by staining reagents and
then visualised under high power of
magnification (1000X) of compound microscope.
• An electron microscope is used for clear
visualization of internal structure of bacteria.

15. SHAPE OF BACTERIA
• On the basis of shape
bacteria are classified as
• 1. Cocci
• 2. Bacilli
• 3. Vibrios
• 4. Spirilla
• 5. Spirochetes
• 6. Actinomycetes
• 7. Mycoplasma

16. ARRANGEMENT OF BACTERIAL CELLS
• Cocci appears as several
characteristics
arrangement or grouping:
• 1.Diplococci
• 2.Streptococci
• 3.Tetracocci
• 4.Staphylococci
• 5.Sarcinae

17. Microscopy
• The morphological study of
bacteria requires the use of
microscopes. Microscopy has
come a long way since
Leeuwenhoek first observed
bacteria using handground
lenses. The types of
microscope are
• (1) Light or optical microscope
• (2) Phase contrast microscope
• (3) Dark field/ Dark ground
microscope
• (4) Electron microscope

18. Sample Preparation for the Study
through Microscope
• Living bacteria are
difficult to observe under
microscope directly for
the reason that they are
of very small dimensions
and most bacteria are
colorless hence there is
utmost need to prepare
bacterial samples in such
a way so as to make them
visible under microscope.

19. Fixation
• It is the first step in sample preparation
and has the aim of preserving tissue in its
original state. Specimens for light and
electron microscopy are commonly fixed
with a solution containing chemical that
crosslink most proteins and nucleic acid.
Fixatives are acids and aldehydes such as
acetic acid, picric acid, formaldehyde, and
glutaraldehyde. OsO4 vapours used for
preparing samples for SEM analysis

20. Staining
• Most biological materials show little contrast
with their surrounding unless they are strained.
In the case of light microscopy, contrast can be
enhanced by using colored stains which
selectively absorbed certain wavelength.
Specimens for light microscopy are stained to
visualize the structural features. Many chemical
stains bind to specific molecules present in the
specimen. For example, hematoxylin, bind to
basic amino acid (lysine and arginine) of
different proteins, whereas eosin binds to acidic
molecules such as DNA and side chains of
asparatate and glutamate)

21. Types of staining:
• Simple Stains :
Dyes such as methylene blue or basic fuchsin are used for simple
staining. They provide colour contrast, but impart the same colour to
all bacteria.
• Negative Staining :
Bacteria are mixed with dyes such as Indian ink or nigrosin that provide
a uniformly coloured background against which the unstained bacteria
stand out in contrast. Very slender bacteria like spirochetes that
cannot be demonstrated by simple staining methods can be viewed by
negative staining.
• Impregnation Methods:
Cells and structures too thin to be seen under ordinary microscope
may be rendered visible if they are impregnated with silver on the
surface. These are used for demonstration of spirochetes and bacterial
flagella.

22. • Differential Stains:
These stains impart different colours to different bacteria
or bacterial structures, the two most widely used
differential stains are the Gram stain and Acid fast stain.
The gram stain was devised by histologist Christian Gram
as a method of staining bacteria in tissues. Gram positive
cells are simpler chemical structure with a acidic
protoplasm. It has a thick peptidoglycan layer. Teichoic
acids are intertwined among the peptidoglycan and the
teichoic acids are the major surface antigen determinants
• The acid fast stain:
was discovered by Ehrlich, who found that after staining
with aniline dyes, tubercle bacilli resist decolourisation
with acids. The method as modified by Ziehl and Neelsen,
is in common use now.

23. Thank you

24. • “Bacteria and Viruses.” FoodSafety.gov.
Updated 21 Nov. 2019.
• Linares, Daniel M., et al. “Beneficial Microbes:
The Pharmacy in the Gut.” Bioengineered,
Taylor & Francis, 28 Dec. 2015