Discuss the distinction between gram-negative and gram-positive bacteria. In the laboratory, how is this determined?
What are differences between these two groups of bacteria? What will be an ideal response?
Concepts to Consider: Gram-positive bacteria are those that absorb and retain crystal violet,
a violet pigment that shows under a microscope. Gram-negative do not retain this pigment
and, therefore, appear red. This effect is due to the fact that gram-positive bacteria have very
thick peptidoglycan cell walls, which absorb and retain the crystal violet pigment. Gramnegative
bacteria do not have thick cell walls and, therefore, do not retain the pigment very
well. The differences in the cell walls between gram-positive and gram-negative bacteria
have a bearing on how certain drugs affects these two bacterial types. Gram-positive bacteria
are very susceptible to penicillin because their cell walls are weakened by the drug. Gramnegative
bacteria are not easily harmed by penicillin. As a result, gram-negative bacteria are
much harder to control.
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The best explanation for why gene control is better understood in prokaryotes than in eukaryotes is
Some tropical rain forests are the source of a plant that proved to be useful in fighting:
a. malaria b. influenza c. HIV d. heart disease e. cancer
Gene expression requires the participation of the
following three types of RNA: __________, __________and __________. Fill in the blank(s) with the appropriate word(s).
Evidence in support of the endosymbiotic theory includes
A) linear DNA in mitochondria and chloroplasts. B) a single membrane enclosing the mitochondria and chloroplasts. C) the presence of 70S ribosomes in mitochondria and chloroplasts. D) the presence of 70S ribosomes in mitochondria and chloroplasts and a single membrane enclosing the mitochondria and chloroplasts linear DNA in mitochondria and chloroplasts. E) the presence of 70S ribosomes in mitochondria and chloroplasts and a single membrane enclosing the mitochondria and chloroplasts.