Multiple Choice
Why are penicillins often more effective against gram-positive bacteria than gram-negative bacteria?
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7. Prokaryotic Cell Structures & Functions
Gram-Positive vs. Gram-Negative Cell Walls
Multiple Choice
The outcome of the Gram stain is based on differences in the cell's _______.
A
cell wall structure
B
plasma membrane composition
C
flagellar arrangement
D
ribosomal RNA sequences
Verified step by step guidance1
Understand that the Gram stain is a differential staining technique used to classify bacteria into two major groups: Gram-positive and Gram-negative.
Recall that the key difference between Gram-positive and Gram-negative bacteria lies in their cell wall structure, specifically the thickness of the peptidoglycan layer and the presence or absence of an outer membrane.
Recognize that Gram-positive bacteria have a thick peptidoglycan layer that retains the crystal violet stain, appearing purple under a microscope, while Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, causing them to lose the crystal violet stain and take up the counterstain (safranin), appearing pink or red.
Note that other options such as plasma membrane composition, flagellar arrangement, and ribosomal RNA sequences do not directly affect the outcome of the Gram stain.
Conclude that the outcome of the Gram stain is based on differences in the cell's cell wall structure.
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