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What is a glycocalyx?
- The glycocalyx is a sticky substance composed of polypeptides (diff between the ones in our cells and bacterial cells), polysaccharides (same in our cells and bacterial cells) or both.
- It is produced in the cytoplasm and secreted to the outer part of the cell wall.
- It provides a protective element against environmental stress.
It can be used for nutrition.
Bacteria can draw back in sugar for use of energy
What makes the glycocalyx a slime layer/capsule?
If loosely attached to the wall, it is called a slime layer.
- If adhered tightly to the wall, it is called a capsule.
- Both variations give an adherence capability to the organism.
- Capsules and slime layers are more typical of graham positive
Clinical significance of glycocalyx?
- The slime layer form is associated with some forms of dental decay.
- The capsule form:
- - Inhibits phagocytosis
- - Many organisms are not infectious without a capsule
- Capsule genes can be transferred between organisms.
How are fimbriae and pili alike?
Both are involved in adherence.
- Both appear as sticky projections which are shorter than flagella.
- They are found on Gram-negative organisms.
- Both are composed of pilin protein subunits.
- Used for transfer to another cell, sometimes “sex” pilus, allows for sex between 2 bacteria. Bacteria can pick up plama, short pieces of DNA
- Bacteria can produce pili,
- find another bacteria to attach to it,
- replicate DNA, transfer plasma DNA over to the next step, now new cell has the
- DNA and that is the purpose of pili, to move DNA from one bacteria to the
- Axial filaments are little modified flagella or endoflagella that wrap around
- spirochete and allow for movement
- The corkscrew motion gives the bacterium the ability to bore through tissue (staying in).
- They allow organisms to get into the blood as well as other tissues (damage the host).
What are flagella?
- Flagella are used only for motility.
- They are long structures that extend far beyond the cell wall and even beyond the glycocalyx.
- They make it possible for bacteria to move from their point of origin to other places in the body.
- Example: E. coli can move from the large intestine, where it is harmless, to the urinary tract, where it can cause serious infection.
- Not used for attachment
Flagella and their roters
- Basically allows bacteria to swim, gives it a propeller
- Flagella have a roter that is the moving force for the flagella
- Being gram + or gram – will depend on outer region or basil body of the portion of the flagella.
- The roter allows the flagella to rotate and 360 degrees.
- Monotrichous – one flagellum located at the end of the cell
- Amphitrichous – two flagella, one at each end of the cell
- Lophotrichous – two or more flagella located at the same end of the cell
- Peritrichous – flagella surround the entire cell.
Flagella movement allows for
- opportunistic infections
- escape from host defense (defeat of host defense)
- systemic infection ( can create just through movement)
Flagella movement directions
- Clockwise – bacteria tumbles and changes direction
- Counterclockwise- bacteria runs in a single direction
length and number flagella
- - Sometimes pili will be longest and sometimes flagella will, on ave prob the same length
- -Can be monotrichous and can also have a very high amount
Length and number fimbriae
- - Shortest
- - Has the most, are everywhere, are there to coat the bacterial
length and number pili
- - sometimes pili will be longest and sometimes flagella, on ave prob the same length
- -will have least amount