Bacterial Properties Flashcards
what is the resolution limit of light microscopes?
200nm
what are some types of light microscopy techniques?
brightfield and darkfield, phase contrast, fluorescence, DIC, two-photon
What are the types of electron microscopy?
Transmission - views things in 1D
Scanning - views things in 3D
what is the process of gram staining?
Crystal violet - dark purple
Iodine - lighter purple
Alcohol - neg = clear and positive = stays purple
Safranin = neg goes pink, positive stays purple.
what is the colour of gram +ve and -ve once stained?
Positive: purple
Negative: pink
what is the purpose of the cell wall?
It protects the bacteria against osmotic and environmental pressure. It defines shape and allows for uniform cell division. It does not exist on eukaryotic cells, meaning prokaryotic cells can be identified by the body. Targeted by penicillin.
what is the purpose of a biofilm?
Form around multiple species of bacteria and allow it to stick to a surface and grown and divide in optimum conditions, together. Biofilms allow adhesion and resistance. E.g. dental plaque.
what is a bacterial capsule?
it is a polysaccharide that can be covalently attached to the cell wall - it surrounds the cell wall. They can be immunogenic to help against immune responses.
what is the Proteinaceous S-layer?
It is the outermost layer of the cell envelope. it is a crystalline lattice of a single protein taht provides extra protective layer.
what are the surface appendages?
Pili and fimbriae. Fimbriae are smaller. they are attachment and adhesion proteins that are important in pathogenesis. they can also support gene transfer by conjugation - bacteria come in close proximity and the pili from each will connect and exchange DNA. this helps the spread of microbial resistance.
what are endospores?
provide resistance to heat, solvents and lysozymes and are triggered by bacterial starvation. they allow bacteria to lie dormant. it adds several outer layers, the toughest being the cortex.
what is the flagella?
Rotary motor helping the cell become motile. they give directionality - they may sense food and direct the bacteria there. This is done by chemotaxis. they have a rotation and helical structure.
what is green fluorescence protein (GFP)? and how does it work in fluorescence microscopy?
Scientists isolated the GFP and found that it could be tagged to other proteins to create a ‘hybrid protein’. This allows proteins to be tracked.
