This document summarizes the ultrastructure and morphological classification of bacteria. It describes the three main layers that make up the bacterial cell - the capsule/glycocalyx, cell wall, and cytoplasm. The cell wall provides structure and protection, while the capsule aids in nutrient absorption and adherence. Inside the cell are genetic material, ribosomes, flagella, and other structures. Bacteria can be classified morphologically based on their shape, including cocci (spherical), bacilli (rod-shaped), spirilla (spiral), and others. Plasmids may also be present, containing non-essential genes.
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Ultra structure of bacteria.pdf
1. Ultra structure And Marphological
Classification of Bacteria
Abhishek Yadav
Seiko college of pharmacy, Lucknow
B.Pharm 2nd year
2. Ultra-structureof Bacteriacell
There are three layer in bacterial cell.
• Capsule/Glycocalyx
• Cell wall
• Cytoplasm
Capsule/Glycocalyx :-
A gelatinous substance,usually composed of polysaccharides or polypeptide,
surrounds some bacteria. Glycocalyx forms a tightly bound layer on the cell wall, and
this layer called a capsule. This layer protects the cell from desiccation and antibiotic
exposure.Theystick to surfaces such as root surfaces, human teeth, and tissues
because of their sticky nature. It also keep bacterial cells nourished.
3. Cell wall :-
Bacteria have granular and rigid cell walls. It provide protection and gives the cell
its shape.Chemically, the cell wall consists of a complex compound called
peptidoglycan or mucopeptide (N-acetylglucosamine, N-acetylmuramic acid, and
peptide chains containing four or five amino acids). The porin polypeptide is among
the most abundant polypeptides present and is crucial for solute diffusion.
4. Lipoproteins are found in the plasma membrane. Molecular and ion traffic is
controlled by the plasma membrane. In addition to enzymes that take partin
oxidation of metabolites (the respiratory chain) and photosystemsinvolved in
photosynthesis, the plasma membrane houses enzymes in charge of
photosynthesis.
Plasmamembrane:-
Cytoplasm :-
The cytoplasm is semitransparent and thick. Several cell components can
be found within it, including ribosomes. Included in cytoplasm are
glycogen, Sulphur granules, poly-?hydroxybutyrate crystals, and
polymerized glycerol molecules.
5. BacterialChromosome :-
Eukaryotes have a membrane enclosing the chromosomes, whereas bacteria have a
single circular DNA molecule tightly coiled. Nucleoid or Genophore is the name of
this genetic material. E. coli's DNA measures approximately 1mm when uncoiled,
yet contains all its genetic information, which is mind-boggling. There is no histone
protein binding to the DNA. The circular DNA molecule that makes up each
chromosome is attached to the plasma membrane at one point, and it is thought
that this attachmentmay aid in separating two chromosomes after DNA replication
occurs.
6. Plasmids :-
Plasmids are self-replicating, circular, doublestranded elements that are
extrachromosomal. Genes related to fertility, antibiotic resistance, and heavy
metals can be found in them. The enzymes assist in producing bacteriocins and
toxins thatare not present in bacteria's chromosomes. Most plasmids are
between 1 and 500 kb in size, and contribute between 0.5 and 5.0% of the total
DNA of bacteria. Each cell may contain one or more plasmids. Depending on their
function, plasmids can be classified into various types. They are among others F
(Fertility) factor, R (Resistance) plasmids, Col (Colicin) plasmids, Ri (Root-inducing)
plasmids, and Ti (Tumour-inducing)plasmids.
Mesosomes :-
Plasma membranes are folded into lamellae, tubules, and vesicles, which are
found inside the cell. By clumping them and folding them together, they
maximize their surface area, helping to respire and allowing binary fission.
7. Polysomes/Ployribosomes:-
Proteins are synthesized by ribosomes. There are between 10,000 and 15,000
ribosomes per cell. There are two subunits to ribosomes: the 50S and the 30S
subunits. Polyribosomes or polysomes are formed when ribosomes are linked by
mRNA.
Flagella :-
Flagella are thin hair-like processes that emerge from the cell wall of many
motile bacteria. A diameter of 20 to 30 um and a length of 15 um can be
measured. Eukaryotic flagella contain 9+2 microtubules, while bacteria have a
single fibril for each flagellum. A flagellum acts as a locomotor. Bacteria differ
according to how many flagella they have and where they are located.
8. Fimbriae/Pilli :-
Gram-negative bacteria (such as Enterobacterium) have hair-like appendages on
the surface of their cell walls called pili or fimbriae. Pili range in size from 0.2 to 20
m in length and have a diameter of about 0.025 m. Pili are not the only type of pili
found in the body. There are also sex pili that assist in conjugation.
9. Marphological Classification of Bacteria
There are several types of bacteria, dependingon their shape.
• Cells with a ball or ovalshape (from the Greek word kokkos meaning berry) are calledcocci.
• It is a rod-shaped cell (which comes from the word baculusmeaning rod).
• Its name derives from its characteristicvibratory motilityand resembles a comma shaped rod.
• The spiral is a rigid form.
• The spirochete is a spiral form (from speira meaning coil and chaite meaning hair) that is flexiblyarranged.
• From the Greek words actis, meaning ray, and mykes, meaning fungus, actinomycetesappearas ray-like
spots on tissue lesions.
• The morphology of mycoplasmasis not stable because they lack a cell wall.
• They come in the form of curved bodies and filamentousstructures.