staining process and the pertinent cellular components that cause cells to stain

Question

staining process and the pertinent cellular components that cause cells to stain a particular color. On the other What color would the E. coli cell be following a Gram stain? Explain why with a clear explanation of the Gram hand, what color should Cyanobacteria stain (you were given the answer above, don't mess this up)? Exp why, once again drawing from your knowledge of how the Gram staining procedure works to cells, might it be challenging to accurately stain Cyanobacteria. (6 points) Don Outer membrane, PURP GRM stain negative...you are now focused on the External Layer (EL) of P. uncinatum. Turns out that the EL is the junctional pore location of electron-dense "slime" extrusion, as well as the location of fibril attachment (both the slime and active fibril activity allow for "gliding" locomotion). Non-motile strains of P. uncinatum have locations for fibrils along the EL, but empty pore channels (meaning no "slime" production). This is contrasted with highly motile, gliding strains that have BOTH the production of "slime" as well as active fibrils. Which is STAIN PRO . Now expanding on the thought process that the more cellular layers involved, th e less likely the Gram stain will more likely to stain gram negative, a motile or non-motile strain? Why? (3 points) ram +) more layer

Explanation / Answer

3.E.coli would stain pink in gram staining and hence would be gram negative.E.coli cells cannot retain the primary stain (crystal violet )i.e they tend to lose the crystal violet stain after the decolourization step.The reason behind this is that E.coli possesses an outer membrane that is made up of lipopolysaccharide.In the 3rd step of gram staining i.e decolorisation step addition of 95% alcohol increases the porosity of lipopolysachride layer and they are lost exposing the inner thin peptidoglycan layer which under action of 95% alcohol tend to leak away all of the crystal violet stain.Therefore when counterstain i.e saffranin is added ,the now decolorised cells take up safranin and stain pink.In Cyanobacteria there are many layers present outside the cell membrane with the outermost layer being the slime coat, next being capsule,then mucoid sheath, then outer membrane and then at last comes the peptidoglycan layer.It is known that peptidoglycan layer is thick in cyanobacteria which means it should be gram positive but it actually is gram negative.The reason might be that the capsule layer might be having low affinity for stains. So when primary stain, crystal violet and mordant are added the cells dont take up the stain.In the decolorisation step,on adding 95% alcohol the porosity of outer membranes increase which therefore take up the counter stain i.e. saffranine and appear pink.

4.The non motile strain is more likely to stain gram negative. This is because the non-motile strains have empty pore channels that do not produce slime such that decolorisation step can take way the primary stain and stain the cells with counterstain i.e saffranin ;making them appear pink and hence gram negative.

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