Which of the following statements is true about bacterial genomes and plasmids?

• A. Plasmids contain all the essential genes required for bacterial survival.
• B. Plasmids are extrachromosomal DNA molecules that can replicate independently of the bacterial chromosome.
• C. The bacterial genome is always circular and located outside the cell membrane.
• D. Bacterial chromosomes and plasmids are both inherited exclusively through vertical gene transfer.

Answer: (B)

Verified step by step guidance

1. Understand the difference between bacterial chromosomes and plasmids: Bacterial chromosomes contain the essential genes required for survival, while plasmids are smaller, extrachromosomal DNA molecules that often carry non-essential but beneficial genes.
2. Recall that plasmids can replicate independently of the bacterial chromosome, meaning they have their own origin of replication and do not rely on the chromosome for replication.
3. Recognize that bacterial genomes are typically circular and located inside the cell, specifically in the nucleoid region, which is within the cytoplasm but not outside the cell membrane.
4. Consider the modes of gene transfer: vertical gene transfer is from parent to offspring, but plasmids can also be transferred horizontally between bacteria through processes like conjugation.
5. Evaluate each statement based on these concepts to determine which one accurately describes plasmids and bacterial genomes.