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Structure of bacteria.
Structure of a typical bacterium. The numbered parts are: (1) pilus, (2) plasmid, (3) ribosome, (4) cytoplasm, (5) cytoplasmic membrane, (6) cell wall, (7) capsule, (8) nucleoid, and (9) flagellum (Source: LadyofHats [Public domain
Pili - hair-like structures that help bacteria attach to surfaces and other bacteria
Plasmids - genetic material (DNA)
Ribosomes - structures that make proteins
Cytoplasm - a gel-like material in which the ribosomes and genetic material are suspended
Cytoplasmic Membrane - a thin layer of phospholipids and proteins that controls the movement of nutrients in and out of the cell
Cell Wall - a rigid wall that gives the cell its structure and protects the plasma membrane
Capsule - a third layer that helps prevent the bacteria from drying out or being engulfed by larger microorganisms (only present in some types of bacteria)
Nucleoid - a mass of genetic material (DNA)
Flagellum - structure that helps the bacteria move around and sense their environment
One of the most important structures of a bacterial cell is the cell wall. Bacterial cell walls have quite a few functions. They protect bacteria from bursting. They also help bacteria maintain their shape. Finally, they control molecules going in and out of the cell. Scientists can use the thickness of the cell wall to identify and categorize different types of bacteria.
Classification of bacteria.
Bacteria Shapes
Bacteria can be assigned to three major groups based on shape. These include bacteria that are spherical (cocci), rod-shaped (bacilli) and spirals and others.
Bacteria can be grouped according to their shape. Bacteria are typically either spherical, rod-shaped or have a spiral shape
We often think of bacteria as being ‘bad’. That’s because many bacteria are pathogenic, which means that they can make us sick. There are lots of diseases and conditions caused by bacteria. Examples of diseases or conditions that are caused by pathogenic bacteria include:
tetanus
typhoid fever
tuberculosis
strep throat
anthrax
various forms of food poisoning
Cell wall of bacteria ( Peptidoglycan layer
• Peptidoglycan layer made up two part (Glycan+ peptide)
• Glycan part made up two acids
• NAM (N- Acetylmuramic acid)
• NAG ( N Acetylglucosamine acid)
• This two different acid are attended to each other’s by Beta 1,4 glycoside bond
• Two different chain are attended to each other by 4 carbonic group
• This peptide chain are attached to each other by peptide Bridge.
Note:-
• main function of the peptidoglycan layer is that it prevent a bacteria from osmotic burst
•
Teichoic acid in gram positive bacteria cell wall
• Teichoic acid are only found in gram positive bacteria it is absence in gram negative bacteria
• Some teichoic acid are present on the surface of cell wall which is called wall teichoic acids
• Some teichoic acid are attended to the cytoplasmic members which is called a Lipoteichoic acid
Outer membrane of gram negative bacteria
Outer membrane of gram negative bacteria made up Phospholipid and some other important components as
• Protein ( Bruno’s lipoprotein and porins )
• Endotoxin
• Exotoxin
A
Endotoxin in gram negative bacteria
•
• This lipid part is very pathogenic but not immunogenic and polysaccharide is very immunogenic but not pathogenic
Exotoxin in both type of bacteria
• Exotoxin may be present in gram negative bacteria and gram positive bacteria this Exotoxin is highly immunogenic as well as highly pathogenic and they are found in protein forms
• Some special types of bacteria are produce special tube like structure this mechanism of bacteria are called a injectisome
Bacteremia:- means bacteria only present in body
Septicaemia:- means bacteria are division
Toxemia:- bacteria Producing a disease
4. Structure of capsule
•
•
• If are combined to each other and the form a
• Capsule prevent the bact
• It prevent a bacteria cell for lysis
• Prevent a bacteria for Bacteriophages
• Protect a bacteria for drying up
Demonstration of capsule of bacteria
• Bacteria capsule demonstrates by two methods of bacteria capsule
• Serological method is Quellung reaction use for demonstration of ca
Spores and it’s formation
• Spore are highly resistance structure of bacteria this
• Bacteria spore can only kill by the autoclaving method (121°C for 10 to 20 minutes)
Structure of spores
Spores made up many layers as [ core-cortex-coat -exosporium ]
Sporulation
Sporulation is a process of formation of spore from the ve of spores
• Cortex formation:- immature spores attach a special spore
Demonstration of spores
Plasma membrane
• Plasma membrane
24 сен 2024
