Final answer:
A plasmid carries genes from one organism into a bacterial cell and can transfer antibiotic resistance or other advantageous traits. Plasmids replicate independently and are used in genetic engineering.
Step-by-step explanation:
The component that carries a gene from one organism into a bacterial cell is a plasmid. Plasmids are small, circular, double-stranded DNA molecules that exist in the cytoplasm of bacteria separately from the bacterial chromosome. They are capable of independent replication and can carry genes that provide advantageous traits to the bacteria, such as antibiotic resistance. Plasmids can be transferred between bacteria via processes such as conjugation, transformation, or transduction. In the context of genetic engineering, plasmids are often used as vectors to transfer genes into bacteria, which can then express the gene of interest.