Question

The following is TRUE for Mycoplasma EXCEPT:

• A. Multiply by binary fission
• B. Are sensitive to the beta-lactam group of antibiotics
• C. Can grow in cell-free culture media
• D. Require sterols for growth

Hint:

Mycoplasma has no cell wall, so beta-lactam antibiotics, which target cell wall synthesis, cannot act on it.

Answer 1

The Correct Option is B

Mycoplasma stands out among bacteria for one reason above all: it has no cell wall. Almost every unusual fact about it traces back to that single feature. Let's test each option against this.

1. Multiply by binary fission: true. Mycoplasma reproduces the same way most bacteria do, by simple splitting into two cells.
2. Sensitive to the beta-lactam group of antibiotics: false. Beta-lactams work only by stopping the building of peptidoglycan, the material of a bacterial cell wall. Mycoplasma has no cell wall and no peptidoglycan, so these drugs have nothing to act on. It is naturally resistant to the entire beta-lactam class.
3. Can grow in cell-free culture media: true. Unlike obligate intracellular organisms, Mycoplasma grows on enriched artificial media such as PPLO agar, without needing to be inside a host cell.
4. Require sterols for growth: true. With no rigid wall to protect it, Mycoplasma strengthens its membrane using cholesterol taken from the growth medium, usually supplied as serum.

Three of the four statements follow directly from the lack of a cell wall. Beta-lactam sensitivity is the one exception, since a drug that targets wall building cannot work on an organism that has no wall.

Let's summarize:

• No cell wall is the single feature that explains Mycoplasma's biology.
• It grows on cell-free media and needs sterols for its membrane.
• Beta-lactams fail against it because there is no peptidoglycan to attack.

The false statement is that Mycoplasma is sensitive to beta-lactam antibiotics.