Final answer:
The starting point and direction of DNA transfer in bacterial conjugation are determined by the origin of transfer (oriT) within the F factor or fertility factor.
Step-by-step explanation:
During conjugation, the starting point and direction of DNA transfer are determined by a DNA sequence within the F factor called the origin of transfer (oriT). Conjugation is a process where DNA is directly transferred from one bacterium to another. In Escherichia coli (E. coli), the genes that enable a cell to initiate conjugation are located on a plasmid known as the F plasmid or fertility factor. Cells with the F plasmid (F+ cells) can form a conjugation pilus and act as donors, while cells without the plasmid (F- cells) are recipients. The F plasmid can also integrate into the bacterial chromosome forming an Hfr cell which can transfer chromosomal DNA to an F- cell using a similar process.