Difference Between Plasmid and Cosmid

Thekey difference在质粒和宇宙之间the plasmid is a double-stranded, circular and closed extra-chromosomal DNA present in bacteria and archaea while the cosmid is a hybrid vector system formed due to combining of thecos细菌的lambda噬菌体和质粒DNA的序列。

基因工程is an advanced study under Biotechnology. Genetic engineering technique can change or alter the genome of living organisms. Furthermore, genetic engineering is helpful in基因治疗and treating genetic disorders. Before inserting genes into another organism’s genome, it is necessary to make a recombinant DNA molecule that can carry the desired DNA fragment and deliver into the host organism. Therefore, during the重组DNA技术, it is done by a vector system. Hence, a vector works as a vehicle or a mediator between donor and host organism. Plasmid and cosmid are two types of vectors commonly use in recombinant DNA technology and genetic engineering. Some are natural vectors while some are artificial vectors. The plasmid is a natural vector while cosmid is an artificially constructed vector. Both types have pros and cons.

内容

1.Overview and Key Difference
2.What is Plasmid
3.什么是宇宙
4.Similarities Between Plasmid and Cosmid
5.Side by Side Comparison – Plasmid vs Cosmid in Tabular Form
6。概括

What is Plasmid?

质粒小,圆形,双链DNA present in prokaryotic organisms mainly in bacteria and archaea. They exist as closed circles inside the bacteria. Also, plasmids are not genomic DNA. Hence, the presence or absence of plasmids in prokaryotic cells does not affect the survival of those cells. Plasmids are extrachromosomal DNA. However, plasmids provide additional advantages to bacteria and archaea. They contain special genes such as antibiotic resistance, resistance to various heavy metals, macromolecule degradation etc.

此外，质粒能够自我复制而无需与染色体联系。它具有基因或自身复制和维护所需的信息。此外，它们是独立的DNA。由于这些特殊特征，质粒在分子生物学中具有巨大使用作为载体。

DNA，抗生素抗性基因，自我复制能力和特殊限制位点的双链性质是重要的特征，它使质粒更适合作为重组DNA技术中的载体分子。而且质粒也很容易分离并转化为宿主细菌。

什么是宇宙?

Cosmid is a hybrid vector system. It is an artificial vector constructed by combining thecoslambda噬菌体颗粒和质粒的序列。这些cossites or sequences are long DNA fragments that comprise of 200 base pairs. They have cohesive or sticky ends that allow the plasmid to fit into the viral DNA. Therefore, the cos sites are vital for packaging of the DNA. There are three cos sites namely cosN site, cosB site and cosQ site. These sites involve in nicking the DNA strand by terminase activity, in holding the terminase and in preventing the degradation of the DNA by DNases respectively.

Cosmids can either replicate single-stranded DNA or double-stranded DNA using a suitable origin of replication. They also contain antibiotic resistance genes that can be useful as markers in selecting transformed cells. Thus, similar to plasmids, cosmids are also good vectors in recombinant DNA technology.

What are the Similarities Between Plasmid and Cosmid?

• Plasmid and cosmid are vectors commonly used in recombinant DNA technology.
• Both are able to self-replicate.
• They have the origin of replication.
• Furthermore, they possess multiple cloning sites.
• 此外，它们包含有用的抗生素耐药基因。
• 外国DNA可以插入两种类型并制成重组分子。
• 两个向量都可以轻松筛选方法。
• 两者都对构建基因组库有用。

What is the Difference Between Plasmid and Cosmid?

质粒和宇宙是基因工程中使用的两种克隆矢量。质粒是细菌和古细菌中存在的小的，圆形的双链牙外DNA分子。另一方面，Cosmid是由Lambda噬菌体DNA和质粒DNA的COS序列构建的杂化载体。这是质粒和宇宙之间的关键区别。此外，质粒最多可以携带25 kb的DNA片段，而COMSID可以含有多达45 kb的片段。因此，这是质粒和宇宙之间的另一个区别。

在质粒和宇宙之间差异的信息图中给出了更多细节。

概括– Plasmid vs Cosmid

The plasmid is a naturally occurring extrachromosomal DNA while cosmid is a hybrid vector of phage DNA and plasmid DNA. Both are cloning vectors used in recombinant DNA technology. Cosmids contain special sticky ends known as cos sites required for体外packaging. On the other hand, plasmids contain several features that make them ideal vectors in genetic engineering. Both can undergo independent replication or体外包装到细菌细胞上。质粒能够包含25 kb长度的外源DNA片段，而宇宙含量能够包含45 kb的外源DNA片段。因此，由于质粒载体无法克隆较大的片段，因此宇宙可用于克隆的目的来克隆较大的DNA片段。因此，这总结了质粒和宇宙之间的差异。

Reference:

1.Nature News, Nature Publishing Group.Available here
2.“Cosmid.” NeuroImage, Academic Press.Available here

Image Courtesy:

1. Spaully的“质粒（英语）” - 自己的工作，(CC BY-SA 2.5)viaCommons Wikimedia
2.”Cosmid (English)”By Zlir’a (CC0) viaCommons Wikimedia