Final answer:
Plasmids are key tools in biotechnology owing to their extrachromosomal nature and ability to carry antibiotic resistance genes. Features such as multiple cloning sites and compatibility with restriction endonucleases facilitate the insertion of DNA fragments, making them ideal for producing recombinant DNA molecules and subsequent products like insulin.
Step-by-step explanation:
Plasmids are extrachromosomal DNA molecules used in biotechnology for molecular cloning. They replicate independently within a bacterial cell and often carry antibiotic resistance genes. The key features that make plasmids valuable in biotech include a multiple cloning site (MCS), which is a sequence containing multiple sites for restriction endonucleases. These enzymes recognize specific DNA sequences, creating cuts that result in 'sticky ends' that can bind with complementary sequences. The subsequent addition of DNA ligase seals the introduced DNA fragments into the plasmid, creating recombinant DNA molecules. Some commonly used plasmids include pBR322 and pBR325. Their ability to promote horizontal gene transfer is leveraged in biotechnology to produce important compounds like insulin.