Final answer:
In reviewing the statements related to DNA repair and homologous recombination, it's determined that statement A is false because homologous recombination can occur in prokaryotic cells. Statements B and C are true, while statement D is false as the template is not always the homologous chromosome from another parent.
Step-by-step explanation:
The statements A through D refer to aspects of DNA repair and homologous recombination. Each statement has been evaluated for its accuracy:
- A. Homologous recombination cannot occur in prokaryotic cells, because they are haploid, and therefore have no extra copy of the chromosome to use as a template for repair. False. Although prokaryotic cells are typically haploid, homologous recombination can still occur using the identical regions of DNA present within the same chromosome or plasmids within the cell.
- B. The first step in repair requires a nuclease to remove a stretch of base pairs from the 5′ end of each strand at the site of the break. True. A nuclease, often in conjunction with other enzymes, initiates repair by removing damaged DNA.
- The 3′ overhang "invades" the homologous DNA duplex, which can be used as a primer for the repair DNA polymerase. True. This is part of the homologous recombination process where the 3′ overhang uses the homologous sequence as a template for repair.
- The DNA template used to repair the broken strand is the homologous chromosome inherited from the other parent. False. In the context of eukaryotic somatic cells, the template is usually the sister chromatid, not necessarily the homologous chromosome from the other parent. However, in meiosis, homologous chromosomes can serve as templates for each other.