Final answer:
Plasmids primarily carry genes that offer advantageous traits like antibiotic resistance and can contribute to bacterial virulence, making them critical for survival under specific conditions and useful in genetic engineering.
Step-by-step explanation:
If plasmids do not carry essential genes for the basic life processes of a bacterium, they primarily carry genes that confer advantageous traits to the bacteria which aids in their survival and adaptation to various conditions.
The genes found on plasmids can offer antibiotic resistance, produce enzymes to degrade atypical compounds, functionalities for producing antibiotics, and sometimes contribute to the virulence of pathogenic bacteria.
Plasmids are involved in horizontal gene transfer and are valuable tools in genetic engineering and biotechnology, making them significant in the context of microbial genetics and modern applications thereof.