Question

Do Bacteria have circular DNA?

Answer 1

Hint: Circular DNA forms a closed loop and has no ends and is found in the cytoplasm of the prokaryotes, mitochondria and chloroplasts. It acts as a vector to transfer genes of interest within the cells.

Complete answer:
Bacteria have a circular chromosome that is located in the cytoplasm and is known as plasmid. Several proteins and RNA molecules and the chromosome together form an irregular shaped structure called the nucleoid which is the region where most of the genetic material is found.
Keeping a plasmid is hard work for a bacterial cell because replicating DNA uses up energy. However by protecting its bacterial host from stress related death, a plasmid maximizes it's chances of being kept around. Bacteria with plasmid under stressful conditions will live longer and have more opportunity to pass on the plasmid to daughter cells. Without plasmid, bacteria are less likely to survive and reproduce. Plasmid contains genes responsible for antibiotic resistance.

Plasmid acts as a delivery vehicle to introduce foreign DNA into bacteria. All the Plasmids that are used to deliver DNA contain genes for antibiotic resistance. They can be copied numerous times. They are well suited to incorporate extra DNA sequences. That's because it can be cut open without falling apart, then snap back together once new DNA has been incorporated.

Note:
Plasmids are separate from the bacterial chromosome and replicate independently of it. They generally carry only a small number of genes, notably some associated with antibiotic resistance.