A Power point presentation on General Features of Prokaryotes. This ppt covers brief information of "General Features of Prokaryotes" useful for introduction lecture as well as for seminar purpose.

1. A POWERPOINT PRESENTATION ON
GENERAL FEATURES OF PROKARYOTES
PRESENTED BY
AQUIB RAZA
M.Sc. I SEMESTER
DEPARTMENT OF MICROBIOLOGY
KNIPSS (SULTANPUR)

2. INTRODUCTION
•All living organisms on earth are composed of one or the other
of two types of cells; prokaryotic cells and eukaryotic cells based
on differences in cellular organization and biochemistry.
•Prokaryotic cells (pro or primitive) do not have a membrane-
bound nucleus. Prokaryotes includes Bacteria and Archaea. All
bacteria and blue green algae are prokaryotes.
•Most prokaryotes are small, single-celled organisms that have a
relatively simple structure.

3. GENERAL FEATURES
• They lack nuclear membrane.
• Mitochondria, golgi bodies, chloroplast and
lysosomes are absent.
• The genetic material is present on a single
chromosome.
• The cell wall is made up of carbohydrates and
amino acids.
• They divide asexually by binary fission.
• The sexual mode of reproduction involves
conjugation.

4. PROKARYOTIC CELL

5. SHAPE
• Depending on their shape, bacteria are classified into several
varieties:
• Cocci: Cocci (s., coccus) are spherical, Eg., Streptococci etc.
• Bacilli: Bacilli (from baculus meaning rod) are related straight,
rod shaped. Eg., Mycobacterium tuberculosis etc.
• Spirilla: They are rigid, spiral shaped cells that usually tufts of
flagella at one or both ends. Example: Helicobacter pylori etc.
• Spirochetes: They are flexible, spiral-shaped bacteria that
have a unique, internal flagellar arrangement. Eg., Treponema
pallidium etc.
• Vibrios: They are curved or comma-shaped rods and derive
from their characteristic motility. Eg., Vibrio cholerae etc.

7. PROKARYOTIC
CELL ORGANIZATION
• Plasma membrane
• Cell wall
• Inclusion bodies
• Gas vacuole
• Ribosomes
• Nucleoid
• Plasmids
• Capsules and slime
layers
• Fimbriae and pili
• Flagella

8. PLASMA MEMBRANE
• Every prokaryote has a cell membrane, also known as
the plasma membrane. It is a double layer of lipid,
(Phospholipid) that separates the cell from the
outside environment.
• Functions:
• Retaining the cytoplasm.
• Control permeability.
• Transport electrons and protons for cellular
metabolism.
• Contain enzymes to synthesise and transport cell wall
substance.

9. FLUID MOSAIC MODEL OF PLASMA MEMBRANE

10. • The cell wall of prokaryotes is composed of
peptidoglycan.
• Functions :
• Maintain the cell’s shape.
• Protect the cell interior.
• Prevent the cell from bursting when cell takes
up water.
CELL WALL

11. GRAM POSITIVE AND GRAM NEGATIVE
CELL WALL
• Gram-positive bacteria lack an outer
membrane but are surrounded by layers of
peptidoglycan many times thicker than is
found in the Gram-negatives. Eg.,
Mycobacterium tuberculosis
• Gram-negative bacteria are surrounded by a
thin peptidoglycan cell wall, which itself is
surrounded by an outer membrane containing
lipopolysaccharide. Eg., E.coli

12. GRAM POSITIVE AND GRAM NEGATIVE CELL WALL

13. CAPSULE
• Many prokaryotes have a sticky outermost
layer called the capsule, which is usually
made of polysaccharides.
• The capsule helps pathogenic bacteria to
resist phagocytosis . Eg., Streptococcus
pneumoniae.
• They prevent the cell from drying out.
• They aid in attachment to solid surfaces.

14. PROKARYOTIC CYTOSKELETONS
INCLUSION BODIES AND GAS VACUOLE
1. Inclusion bodies are non-living granules of
organic and inorganic materials. These bodies
are used for storage.
2. Gas vacuole, a structure that provides
buoyancy to some aquatic prokaryotes.
• Gas vacuoles, are present in many
photosynthetic bacteria and a few other
aquatic prokaryotes such as halobacterium (a
salt loving archaeon).

15. INCLUSION BODY AND GAS VACUOLE

16. RIBOSOMES
• Ribosomes are very complex structures made of
both protein and ribonucleic acid (RNA). They are
the site of protein synthesis.
• Bacterial and archaeal ribosomes are called 70S
ribosome and are constructed of a 50S and a 30S
subunit.

17. PROKARYOTIC RIBOSOME
(30S SUBUUNIT AND 50S SUBUNIT)

18. NUCLEOID AND PLASMIDS
• The nucleoid is an irregularly shaped region that
contains the cell’s chromosome and numerous
proteins.
• Nucleoid is also known as nuclear region, the
nuclear body, and chromatin body.
• Plasmids are small, double-stranded DNA
molecules that can exist independently of the
chromosome. Both circular and linear plasmids
have been documented, but most known
plasmids are circular.

19. NUCLEOID AND PLASMID

20. EXTERNAL STRUCTURES
FIMBRIAE AND FLAGELLA
• Many bacteria and archaea have structures that
extend beyond the cell envelope. These structure can
function in protection, attachment to the surfaces, etc.
• FIMBRIAE- Many bacteria and archaea have short,
fine, harelike appendages known as Fimbriae.
• FLAGELLA- They are hairlike structure that acts
primarily as an organelle of locomotion in the cells of
many living organisms. Most motile prokaryotes move
by use of flagella.

21. FIMBRIAE AND FLAGELLA

22. 𝓣𝓱𝓪𝓷𝓴 𝔂𝓸𝓾