Eng.Abdulrahman Mohamud Dirie Education BSc in Marine and Environmental Science from Hudeida University in Yemen 2014. MSc in Water policy from Pan African university institute of water and energy science inc. climate change – PAUWES. Work Executive Director of Somalia Water Partnership (SWP) Head of Marine Biotic Resources at Somali Marine Resource Research Center (SMRRC). He is a senior lecturer at Somalia Marine Academy and former senior lecturer at Benadir University and Darul Hikma University.

1. Introduction to Bacteria
Definition , Structure and Function
Prepared by : Adulrahman Mohamud Dirie
For year : 2020 - 2021
Federal Republic of Somalia
Ministry of Education, Culture and Higher Education
Somali Marine Academy
Faculty of Marine Science
General Microbiology

2. Shirt Bio ofthe Author:
Eng.AbdulrahmanMohamudDirie
Education
BScin Marine andEnvironmentalScience from HudeidaUniversity in Yemen
2014.
MScin Waterpolicy fromPanAfricanuniversityinstituteofwaterandenergy
science inc. climatechange–PAUWES.
Work
ExecutiveDirectorof SomaliaWaterPartnership(SWP)
Head ofMarine Biotic ResourcesatSomaliMarine ResourceResearchCenter
(SMRRC).
He is a seniorlecturer atSomaliaMarine Academyandformersenior lecturerat
BenadirUniversity andDarulHikma University.

3. Definition of Bacteria

4. Definition of Bacteria
Bacteria prokaryotic microorganisms a single-celled
microscopic organisms that lack nuclei and other
organized cell structures."Bacteria" is the plural form
of "bacterium.“
While several bacterial species are pathogenic (capable
of causing disease), most are non-infectious, and
many have critical roles in
decay, fermentation, nutrient recycling, and nitrogen
fixation. Bacteria are usually classified as gram-
positive or gram-negative based on a basic
microbiological staining procedure called the gram
stain. They come in a variety of shapes and sizes.

6. Shapes of Bacteria

7. Shapes of Bacteria

8. Size of Bacteria

9. Size of Bacteria
Cocci are true spheres with diameter ranging between
0.75 to 1.25 µm (and average of 1 µm).
Bacilli varyin length from 2-10 times their width.
Coccobacilli are very short bacilli.
Filaments are long threads of bacilli which have not
separated into single cells.

10. Were are Bacteria
found?!

11. Environment bacteria
Found everywhere under the earth to a distance
of 400 meters - in the air at high altitudes, at
high temperatures around the craters - in
the polar regions, objects within objects
(animals in the digestive and respiratory
systems), their diet is the carbon dioxide and
produce oxygen.

12. Structure of Bacteria and Function

14. Flagella
 The flagella (singular flagellum) are made up of a
class of linear proteins called flagellins. The basal body
traverses the cell wall and cytoplasmic membrane to
anchor the flagellum and enables it to whirl about its
axis like a propeller.
 Flagel lated bacteria are described as
 monotrichous, lophotrichous or peritrichous,depending
on how the flagella are arranged .
 Function: Flagella give bacteria the
ability to move about activity.

16. Capsule
The capsule of most bacteria consists of a
polysaccharide. The bacteria of a single species
can be classified in different capsular serovars (or
serotypes) based on the fine chemical structure
of this polysaccharide.
Function: 1-Attachment to surfaces
2-protection against phagocytic
engulfment, occasionally killing or digestion
3- reserve of nutrients or protection
against desiccation

18. Plasma
membrane
Plasma membranes in bacteria
are composed of
Phospholipids contain a
polar group attached to a 3
carbon glycerol back bone.
There are also two fatty acid
chains dangling from the
other carbons of glycerol.
The phosphate end of the
molecule is hydrophilic and
is attracted to water. The
fatty acids are hydrophobic .

19. Membranes also contain proteins. Typically 20-30% of
membrane ,Most of them are placed in the
membranes so that the hydrophobic amino acids
associate with the lipids in the membrane and the
hydrophilic amino acids are outside the membrane
interacting with either the cytoplasm.
Function: The plasma membrane is selectively
permeable in that it helps control what moves
into and out of its cell

21. Plasmid or
Chromosome
The “cellular nucleus” in prokaryotes consists of
a tangle of double-stranded DNA, not
surrounded by a membrane and localized in the
cytoplasm .
-the formed, long DNA/protein fibers are
called chromatin;
- each fiber builds a so-called chromosome
-The plasmids of human pathogen bacteria
often bear important genes determining the
phenotype of their cells(resistance
genes, virulence genes).

22. Function:
Protein production
The single most important purpose of the genetic
material of any cell is that it holds all the information
necessary for a cell to carry out its many functions. The
sequence of bases in the DNA contain this information
or genetic code. Generally, this is translated into
messanger RNA and then into protein that then carry
out the many necessary functions of the cell.
DNA is transcribed into RNA that is
then translated into protein by the
ribosome.

23. Examples of advantages
plasmids bestow on the host
-Antibiotic resistance - Some
plasmids code for proteins that
degrade antibiotics-a big
advantage for pathogens.
-Some encode for proteins which
confer virulence factors on the
host. For example- E. coli plasmid
Ent P307 codes for an
enterotoxin which makes E.
coli pathogenic.
-Conjugative plasmids - These
allow exchange of DNA between
bacterial cells.
Additional function:
As Antigen – producing enzyme

24. Cytoplasm and
Ribosomes
- The cytoplasm contains a large number of
solute low- and high-molecular weigh
substances.
- RNA and approximately 20 000
Ribosomescell. Bacteria have 70S Ribosomes
comprising 30S and 50S subunits.
Function: Ribosomes as the organelles for
protein synthesis.

25. Figure 6.29 The 30S ribosomal subunit
is a ribonucleoprotein particle
Figure 6.30 The 70S ribosome consists of
the 50S subunit (blue) and the 30S
subunit (purple) with three tRNAs

26. Cell Wall
Murein(syn.peptidoglycan)
The most important structural element of the
wall is murein, a netlike polymer material
surrounding the entire cell
(sacculus). It is made up of polysaccharide
chains cross linked by peptides.

27. The Structure
of Murein
The Murein
Building Block

28. The cell wall of Gram-positive bacteria:
The murein sacculus may consist of as many as 40 layers (15–80 nm
thick). The membrane lipoteichoic acids are anchored in the
cytoplasmic membrane, whereas the cell wall teichoic acids are
covalently coupled to the murein. The physiological role of the
teichoic acids is possibly they regulate the activity of the autolysins
that steer growth and transverse fission processes in the cell.
teichoic acids can activate the alternative complement pathway and
stimulate macrophages to secrete cytokines.Cell wall-associated
proteins frequently function as pathogenicity determinants (specific
adherence; phagocyte protection).

29. The cellwall of Gram-negative bacteria:
Here, the murein is only about 2 nm thick . The outer membrane is
the salient structural element. It contains numerous proteins
(50% by mass) as well as the medically critical
lipopolysaccharide.
— OmpA (outer membrane protein A) and the murein lipoprotein
form a bond between outer membrane and murein.
— Outer membrane-associated proteins constitute specific
structures that enable bacteria to attach to host cell receptors.

30. Lipopolysaccharide
(LPS):
This molecular
complex, also known as
Endotoxin,is comprised of
the lipoid A, the core
polysaccharide .
Lipoid A:
is responsible for the toxic
effect.

31. Functio
n:
1 the cell wall maintains the overall shape of a bacterial
cell.
2 The cell wall is an essential structure that protects the
cell protoplast from mechanical damage and from
osmotic rupture orlysis.

32. Mahadsanidiin
For your attention