Answer:
Sex pilus or pilus
Step-by-step explanation:
The donor bacterial cells during conjugation have a fertility plasmid. They are called F+ cells. The F genes present on the F plasmid encode enzymes. Some of the genes of F plasmid also code for the formation of sex pilus which is the long and thread-like structures present on the bacterial cell surface. Sex pili are involved in the process of genetic recombination. During conjugation, the sex pilus serves to recognize the surface of F- cell and forms a cytoplasmic bridge between the F+ and F- cells to facilitate DNA transfer.