Is an F’ cell always a merodiploid? Choose the answer (yes,no) and the best explanation that defends the correct answer. A. Yes, F’ cells have bacterial genes on their fertility factor plasmids so they are always a merodiploid. B. No, F’ cells have bacterial genes on their fertility factor plasmids so they cannot be a merodiploid. C. Yes, F’ cells are created from Hfr cells where some of the bacterial genome is pulled into the fertility factor when it recircularizes- so there will always be two copies of the bacterial gene in the cell. D. No, F’ cells are created from Hfr cells where some of the bacterial genome is pulled into the fertility factor when it recircularizes- so there is still only one copy of the bacterial genes in the cell.
The Correct Answer and Explanation is :
The correct answer is A. Yes, F’ cells have bacterial genes on their fertility factor plasmids so they are always a merodiploid.
Explanation:
To understand why this is the correct answer, let’s first define what an F’ cell is and what merodiploidy means.
An F’ cell is a bacterial cell that contains an F’ plasmid, which is a fertility factor plasmid (F factor) that carries not only the fertility genes required for conjugation but also a segment of the bacterial chromosome. This F’ plasmid results from a process in which an Hfr cell (a cell with the F factor integrated into the chromosome) excises the F factor from the chromosome, taking with it a portion of the bacterial genome. When the F factor excises, it may carry along with it some chromosomal genes. This excision event results in an F’ plasmid that can now transfer not only the fertility factor but also some of the bacterial genes to other cells.
Merodiploidy refers to a condition where a bacterial cell has two copies of a specific gene or genomic region: one copy on its chromosomal DNA and one on the plasmid. Since F’ cells carry an F’ plasmid with bacterial chromosomal genes, they are indeed merodiploid for the genes on the plasmid. They have one copy of these genes on their chromosome and an additional copy on the F’ plasmid, making them “partially diploid” for these genes.
Thus, F’ cells are always merodiploid because they possess two copies of certain bacterial genes: one copy on the bacterial chromosome and another on the F’ plasmid. Therefore, answer choice A is correct.
In contrast, the other answer choices are incorrect because they misunderstand the process of F’ plasmid formation or the concept of merodiploidy. For example, choice C is partly true but misleading, as not all F’ cells are guaranteed to be merodiploid for every gene; they are only merodiploid for the genes carried on the F’ plasmid.