Question

Recently an antibiotic resistant strain of bacteria was found to possess a plasmid containing a unique drug resistance gene. Scientists and physicians are extremely concerned about this discovery since this drug resistance gene is usually only found as a part of the bacterial chromosome (nucleoid). In 1 bullet point --Explain the differences between chromosomal DNA (nucleoid) and plasmids. In 2 bullet points -- Explain why the medical community is so concerned about the the discovery of this particular antibiotic resistant strain of bacteria.

Answer 1

1. The points of difference between plasmid and chromosomal DNA (nucleoid) are as follows:

Chromosomal DNA	Plasmid
The chromosomal DNA contains the information required for vital cellular functions such as cell division.	The plasmid is generally composed of genetic information, which can provide certain ecological benefits such as antibiotic resistance.
Chromosomal DNA is generally associated with histone-like proteins, which help in DNA compaction.	Plasmids are not associated with histone-like proteins.
Chromosomal DNA is physically attached to the cellular plasma membrane.	The plasmids are freely dispersed in the cellular cytoplasm.
The replication of chromosomal DNA occurs only when cell division has to be carried out.	Plasmids replicate independently of the cell division process.

2. In most of the antibiotic-resistant cases, the gene for antibiotic resistance is located on the chromosomal DNA (nucleoid). However, in the given case, the antibiotic resistance gene is located on the plasmids. Plasmids are extrachromosomal genetic materials and can be easily propagated within species through the horizontal gene transfer process. Thus, the given bacterium can spread the antibiotic resistance gene to a large group of microorganisms, thereby, increasing antibiotic-resistant strains. This increase in antibiotic resistance will affect the antibiotic treatment process and will be difficult to manage.