5 Questions
The identification of bacteria by serologic tests is based on the presence of specific antigens. Which of the following bacterial components is least likely to contain useful antigens?
Ribosomes
Which of the following statements concerning the Gram stain is incorrect?
Mycobacterium tuberculosis stains blue because it has a thick lipid layer
Why does Escherichia coli stain pink in the Gram stain?
Because it has a thin peptidoglycan layer
Why is Mycoplasma pneumoniae not visible in the Gram's stain?
Because it does not have a cell wall
What is the primary reason Streptococcus pyogens stains blue in the Gram stain?
It has a thick peptidoglycan layer
Study Notes
Serologic Tests for Bacteria Identification
- Serologic tests identify bacteria based on the presence of specific antigens.
- Ribosomes, cell wall, capsule, and flagella are bacterial components that typically contain useful antigens.
- However, ribosomes are least likely to contain useful antigens.
Gram Staining
- The Gram stain is used to differentiate bacteria based on their cell wall composition.
- Bacteria with a thin peptidoglycan layer, such as Escherichia coli, stain pink.
- Bacteria with a thick peptidoglycan layer, such as Streptococcus pyogenes, stain blue.
- Mycoplasma pneumoniae lacks a cell wall, making it invisible in the Gram stain.
- Mycobacterium tuberculosis stains blue due to its thick lipid layer, not its peptidoglycan layer.
Test your knowledge on the identification of bacteria using serologic tests and the principles of the Gram stain. Practice with these microbiology questions.
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