One bacteria cell has several copies of plasmids. Bacteria occur in extreme conditions too, so they need defense mechanisms. Plasmids help in the exchange of genes horizontally between bacteria. But, this is not a step of cell division.
Some plasmids can be exchanged between two different species. It helps to spread important trait for survival such as antibiotic resistant gene throughout the bacterial population. Thus, the key difference between genomic and plasmid DNA is that the genomic DNA is essential for the survival of organisms while plasmid DNA is not essential for the survival of organisms. Also, a further difference between genomic and plasmid DNA is their sizes.
Moreover, genomic DNA contains vital genes that produce all structural and functional proteins. But, plasmid DNA contains genes that provide additional advantages for the organisms. Hence, this is also a difference between genomic and plasmid DNA. Below info-graphic presents more information on the difference between genomic and plasmid DNA, comparatively. Both types are circular double-stranded DNA.
Codons are used to call for specific amino acids to be bonded together to form proteins. For instance the codon adenosine-adenosine-guanosine AAG calls for the amino acid lysine lys to be incorporated into a protein molecule. The codon AGG calls for the amino acid arginine arg. There are also codons that, under the right circumstances, call for a protein to begin to be formed start codons , or for a protein chain to be finished stop codons.
As you can see from this simple example, DNA can carry a massive amount of information. Figure 1: Adenine binds to thymine; guanine binds to cytosine. A gene is a set of codons that specify a specific protein chain, along with the associated start and stop codons.
In nature, the process for information to be passed on from DNA can occur through either replication or gene expression. There are some important factors to note:. To isolate high yields of plasmid DNA, use cultures in late log phase or early stationary phase.
Prepare cultures using fresh single colonies and fresh selection antibiotic at the right concentration for plasmid maintenance. It is important not to overgrow bacterial cultures as this may result in gDNA contamination in the plasmid extract. Nowadays, there is a kit for everything, and the internet contains vast information about extracting DNA from plasmids, genomes and everything in between!
Has this helped you? Then please share with your network. Hlo When i compare the methodologies of purification of plasmid and bacterial genomic DNA preparation,who can help me to give me some of the reasons for the differences? Great Article. The genomic DNA isolation you have explained. I have the same question but I want is both genomic and plasmid DNA, So, could we be sure that the extract of genomic DNA extraction procedure contain plasmids?
I think you get both genomic and plasmid DNA. If you would like to have only genomic DNA maybe a curing process to get rid of the plasmid is required before. Hi, It is very nice to read your blog. You must be logged in to post a comment. This site uses Akismet to reduce spam. Learn how your comment data is processed.
Learn more. Genomic DNA Extraction: 1. A few words of advice Chromosomes will break during purification because they are simply too large to stay intact; for most applications this is not an issue. Another interesting difference between plasmid and chromosomal DNA in bacteria is a process called conjugation.
This process transfers plasmids between bacteria, sometimes between different species of bacteria that are only distantly related. The transferred plasmid might remain distinct and separate from the bacterial chromosome or become part of it. Plasmid transfer has been important in the rise of antibiotic resistance. Genes that confer antibiotic resistance are often found on plasmids and appear to have been transferred from one bacterial species or population to another.
In general, bacterial chromosomes typically have a higher coding density. This means that a greater proportion of the chromosome is active and provides instructions for protein production. Some plasmids might carry only a few genes, which means they are much smaller than the chromosome and have only a very limited number of functions.
Chromosomes generally carry core genes, which are involved in metabolism that is essential for the bacterium's survival and growth. Plasmids, on the other hand, tend carry useful functional "extras.
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