Plasmid DNA and Chromosomal DNA

A plasmid is a small extrachromosomal DNA molecule that may reproduce independently of chromosomal DNA while remaining physically separate from it. Plasmids are small circular double-stranded DNA molecules that are present in bacteria, archaea, and eukaryotic cells. Plasmids usually carry genes that help an organism survive and provide a selection advantage, such as antibiotic resistance, in nature.

Plasmids are replicons, or DNA units that may self-replicate in the presence of a compatible host. Plasmids, like viruses, are classified as non-living entities. Conjugation is the most common method of passing plasmids from one bacteria to another (even between species).

A chromosome is a long DNA molecule that contains part or all of the genetic material of an organism. Most eukaryotic chromosomes contain histones, which adhere to and condense the DNA molecule with the help of chaperone proteins to keep it intact. The three-dimensional structure of these chromosomes has an impact on transcriptional regulation. Chromosomes are only visible under a light microscope during the metaphase of cell division.

Chromosome recombination during meiosis and subsequent sexual reproduction determine the majority of genetic variation. If these structures are altered improperly by mechanisms such as chromosomal instability and translocation, the cell may undergo mitotic catastrophe.

DIFFERENCE BETWEEN PLASMID & CHROMOSOMAL DNA

What is plasmid DNA?

During reproduction, essential genetic information is passed on to the next individual as part of the inheritance process. Plasmid DNA is a type of extrachromosomal DNA distinct from genomic DNA. It has a round shape and is found mostly inside bacterial cells. It’s a smaller molecule with a variable number of copies in each cell as compared to chromosomes. By definition, it is self-replicative because it has a replication origin.

As a result, they are self-replicating and do not require genomic DNA. This DNA codes for genes that produce effects that aren’t essential for cell function, such as nitrogen fixation and antibiotic resistance. As a result, new genes can be introduced through genetic engineering.

• Some of the functional advantages of plasmid DNA to its host include degradative activities, antibiotic resistance, and virulence
• Natural plasmid DNA has a replication origin and a gene, such as an antibiotic resistance gene. Artificial plasmid DNA, on the other hand, is employed in laboratories to transfer foreign DNA into another cell. The latter type of plasmid DNA contains a replication origin, cloning site, and selection marker
• Plasmid DNA is a valuable tool for scientists and bioengineers since it is easily changeable and has the potential to self-replicate within a cell, making it easier to examine and experiment with

Chromosomal DNA

Chromosomal DNA is the genomic DNA found in prokaryotic and eukaryotic organisms. Eukaryotic genomes have linear chromosomes, whereas prokaryotic genomes have a single circular chromosome. They are double-stranded and contain a replication origin; eukaryotes have several replication origins due to their enormous size. The number of chromosomes in each kind varies depending on the species.

• The majority of eukaryotic chromosomal DNA is made up of packaging and chaperone proteins that bind to the DNA molecule and condense it to prevent it from tangling and creating an unorganized structure
• The carrying of genetic information, the functional unit of heredity, is a crucial function of chromosomal DNA. A gene, as we all know, is a fragment of DNA that contains instructions for making a specific protein or a family of related proteins, and it is carried by chromosomes. The nucleus and mitochondria of the cell include chromosomes, which carry many genes

Construction of Plasmid DNA

Plasmid construction is critical in current genetic manipulation. Currently, the most popular way for creating plasmids is to use restriction enzymes to digest certain DNA sequences and then ligate the resultant DNA fragments with DNA ligase. Another effective method for plasmid construction is gap-repair cloning (GRC), which is extensively utilised in the budding yeast Saccharomyces cerevisiae. GRC takes advantage of the homologous recombination activity found in yeast cells. GRC has been widely employed for the construction of plasmids with complicated structures as well as genome-wide plasmid collections due to its flexible design and efficiency.

GRC is observed in the budding yeast Saccharomyces cerevisiae, which has been utilised to generate large-scale systematic plasmid collections due to its high homologous recombination activity. The target genes are directly cloned into S. cerevisiae cells to explore their function in these circumstances. As a result, GRC is ideal for quick gene function analysis.

Significance of Plasmid 

Plasmids have a wide range of applications, and humans have developed software to store their DNA sequences for use in a variety of procedures.

• Plasmids are used to amplify or copy certain genes in genetic engineering
• In molecular cloning, a plasmid is a type of vector. A vector is a DNA sequence that allows foreign genetic material to be transported from one cell to another, where the genes can be expressed and multiplied
• Small segments of DNA can be cloned using plasmids
• Plasmids can also be used to create large amounts of proteins, such as the insulin-coding protein
• Plasmids are also being investigated as a technique of delivering genes into human cells for gene therapy
• If the patient has a hereditary ailment caused by a gene mutation, cells may be lacking in a certain protein. Cells would be able to express a protein that they now lack by inserting a plasmid into DNA

Significance of Chromosomal DNA

The information that specifies all the proteins that make up an organism, including information about when, in what kinds of cells, and in what quantities each protein is to be generated, is carried by genes, which is the most crucial function of DNA. We examine how genes are normally organized on each chromosome in this section. Eukaryotes have chromosomes that make up their genomes. We also explain the specific DNA sequences that enable correct chromosome duplication and transmission from one generation to the next.

We also face the significant problem of DNA packing. If the DNA in each human cell were stretched end to end, it would measure roughly 2 meters. However, the nucleus, which houses the DNA, is only about 6 micrometers in diameter.

CONCLUSION

As part of the inheritance, vital genetic information is passed on to the new individual throughout the reproduction process. Plasmid DNA is a subset of extrachromosomal DNA that is distinct from genomic DNA. It is circular in form and often occurs inside bacterial cells. As a result, they do not rely on genomic DNA and can self-replicate. This DNA encodes for genes whose results are not required for cell activity, such as metal resistance, nitrogen fixation, antibiotic resistance, and so on. As a result, plasmid DNA is absorbed by both prokaryotic and eukaryotic cells under experimentally generated or natural settings. 

In contrast, chromosomal DNA is the genomic DNA found in prokaryotic and eukaryotic organisms. Eukaryotic genomes have several linear chromosomes, whereas prokaryotic genomes only have one circular chromosome. They are double-stranded and contain a replication origin; the existence of several replication origins in eukaryotes is attributed to their huge size.