Chapter 11, Problem 1P

Summary Introduction

To analyze:

Question asked for the description on the structure of bacterial chromosome and plasmid with their properties.

Introduction:

Bacteria mostly contain single, circular chromosomes or linear chromosomes with double stranded DNA sequences. Bacterial genome is haploid in nature and ranges between $\text{0}\text{.5 to 8}$ MB in size containing several thousand structural genes which code various proteins for their activities and metabolism.

Explanation of Solution

Escherichia coli and Bacillus subtilis are widely used bacterial species with single chromosome, among which E. coli is mostly used, and it has $\text{4}\text{.6}$ million base pairs that encode about $\text{4200}$ genes. In case of some bacteria, they show two or more chromosomes, e.g. Borrelia burdgorferi, Agrobacterium tumefacian, s and Methanococcus jannaschii. Some bacteria like Borrelia burdgorferi and Agrobacterium tumefacians shows linear chromosome.

Bacterial chromosome has little amount of repetitive DNA sequences in multiple copies at intergenic regions, though they rarely transcribe, they serve a key role in replication, recombination, or in regulation of transcription. In bacterial chromosome, chromosomes are densely packed in a series of tight loops in association with a number of nucleoid associated proteins (NAP), i.e. they show several loops by supercoiling of DNA. There are two types of associated proteins a) small nucleoid-associated proteins and b) structural maintenance of chromosomes proteins (SMC).

Conclusion

All aspects are determined.