Scelta multipla
Which two types of acids are characteristic components of the Gram-positive cell wall, in addition to peptidoglycan?
160
views
7. Prokaryotic Cell Structures & Functions
Gram-Positive Cell Walls
Scelta multipla
Upon completion of the Gram stain, Gram-positive cells will appear:
A
green
B
purple
C
pink
D
colorless
Guida verificata passo dopo passo1
Understand the principle behind the Gram stain: it differentiates bacteria based on the structure of their cell walls, specifically the thickness of the peptidoglycan layer.
Recall that Gram-positive bacteria have a thick peptidoglycan layer which retains the crystal violet-iodine complex during the staining process.
Recognize that after the decolorization step with alcohol or acetone, Gram-positive cells remain purple because the thick peptidoglycan traps the crystal violet dye.
Contrast this with Gram-negative bacteria, which have a thinner peptidoglycan layer and do not retain the crystal violet, instead taking up the counterstain (usually safranin) and appearing pink.
Therefore, conclude that upon completion of the Gram stain, Gram-positive cells will appear purple.
Video correlati
Pratica correlata
