Ultra-structuer morphology microorganismes

Morphologg &ultra – structures of microbiology

Lectuer (1)

Dr.Baha,H.AL-Amidi
Ph.D.Microbiology

Microbiology:
It is science that deals with micro – organisms that cannot visible in the naked eyes, encompasses the study of organisms that cause the disease; the host response to infection & the ways in which such infection may be prevented.
dental student study microbiology by basic understanding of general &medical microbiology and detailed knowledge of clinical oral microbiology in order to diagnosis oral microbial infection which are intimately related to the overall treatment plan for their patients. Moreover the two major oral disorders are caries and periodontal disease.
The cellular organisms classified into .
1. Eukaryotes : a- alge , b- fungi c-protozoa
2. Prokaryotes : ( bacteria )
Eukaryotes : organism have true nucleus surrounded by membrane its also contains membrane-bound organelles such as Golgi bodies and chloroplast, there are metabolic function and energy conversion chromosomes present in the nucleus of microorganism there are two types of cell division meiosis & mitosis , DNA is complex with histone proteins, peptidoglycan is not present in the cell wall in these microorganisms :
prokaryotes : organisms related to this group don’t have nucleus; chromosomal DNA is in a circular loop &a plasmid they have few internal structures in the cytoplasm on this group, peptidoglycan present in cell wall of these group,the cell division occur by a process called binary fission













Bacteria : is prokaryotic microorganism can be seen easily by using microscope it is unicellular free living organisms they are capable of performing all essential processes like metabolism and reproduction . they have rigid cell wall containing muramic acid, cytoplasm with no nucleus and contain one chromosomes is present freely in cytoplasm in








aregion called nucloid . bacteria can produce many - enzymes for achieving their metabolic processes and also can
synthesize many factors associated with these pathological called virulence factors also contain number of ribosome s some of these attached to plasma membrane other are free
Bacteria is classified according to their shape into :
1. cocci ( spherical )
2. Rods ( bacilli )
3. spiratum
4. vibrio .
Structure of cytoplasmic bacterial cell
Bacterial cytoplasm is suspension of organic & inorganic solutes in viscous watery solution it contain ribosome s
The cytoplasm is also contain the insoluble cytoplasmic granules which is the reserve material, the cytoplasm granule used as a carbon source so it is storage granule hold excess metabolites, their presence and amount vary with species of bacteria and its metabolic activity .
Many bacteria accumulate in organic phosphate which is called volutin granules which is metachromatic granule e. g (corynebacterium spp ) it is a reserve of energy & phosphate
for cell metabolism &they are characteristically in diphtheria bacilli










Ribosomes: Ribonucleic acid-complex particles, distributed throughout the cytoplasm, They are held together by a strand of ( m RNA )Which are the site of enzymatic concerned with the synthesis of protein.

Bacterial chromosomes: is a single and contain all the genes involved in the growth & survival of bacteria ,Bacteria containes about 1000 genes are located in circular chromos-
ome .Two DNA strands are stabilized by hydrogen bound to form duble helix ,the four nucleotides present in ( DNA) molecule contain nitrogenous base purine(adenine,guanine)
and pyrimidine(Thymine ,Cytosine) are attached to sugar. There is a back bone of alternating deoxyribose and phosphate
However other genetic elements are found with the bacteria these element called ( plasmid & transposons )
Plasmid : the plasmid usually circular DNA present independently for the chromosome and can perform some additional activities to the bacteria, plasmid code for enzymes , toxin or resistance factors and transmit these pathogenic factors in bacteria
Transposons : genetic transferring which can jump from one location to the other in the same or from the plasmids to the chromosome .
The cytoplasm is also contain the insoluble cytoplasmic granules which is the reserve material, the cytoplasm granule used as a carbon source so it is storage granule hold excess metabolites, their presence and amount vary with species of bacteria and its metabolic activity .
Many bacteria accumulate in organic phosphate which is called volutin granules which is metachromatic granule e. g (corynebacterium spp ) it is a reserve of energy & phosphate
for cell metabolism &they are characteristically in diphtheria bacilli
Mesosomes:It is cytoplasmic membrane invaginations of gram-positive bacteria and some gram-negative bacteria,it is
coordinate nuclear and cytoplasmic division during binary fission,Responsible for compartmenting DNA at sporulation.

Baterial cell wall :It is the outermost supporting layer which
Protect the internal structure.cell wall is External to cytoplas-
mic membrane, the structural component of cell wall;composed of mucopeptide(murein).Scaffolding formed by N-acetyl glucosamine & N-acetyl-muramic acid molecule alternating in chain cross linked by peptid chain.
the polysaccharide are covalently bound to peptidoglycan.
It is antigen of Gram negative organisms act as endotoxine.
The Gram positive cell wall is peptidoglycan represent between 40-80% of the total cell wall . The Gram positive cell wall also contain the chemical constituent the techoic acid.
Techoic acid is a polymer of ribitol phosphate and glycerol
Phosphate and is associated with cell wall &cell membrane in gram positive Bacteria.

Functions of Bacterial Cell Wall:
1-protection of internal structure
2-give shape of cell
3-confers rigidity ductility
4-role in division of bacteria
5-offers resistance to harmful effect of environment

Cytoplasmic membrane:It is semipermeable membrane which lies just beneath the cell wall , it is 5-10 nm in width
Electron microscopy shows the presence of three layers
Constituting a unit membrane structure chemically consist of phopholipid with small amount of protein.

Function:
1-It control inflow and outflow of metabolites to and from protoplast.
2-presence in the membrane of specific enzyme which plays important role in passage through membrane
3-It contains some other respiratory enzymes and pigment
(cytochrom system)
4-It provid little mechanical strength to bacterial cell