A cosmid is a type of plasmid (often used as a cloning vector) constructed by the insertion of cos sequences, DNA-Sequences of the Phage Lambda Virus. Figure 1: Schematic drawing of a bacterium with plasmids enclosed. ... The pGEX-3x plasmid is a popular cloning vector. ... A phage (short for bacteriophage, from bacteria and Greek phagein, meaning to eat) is a virus that infects bacteria. ...

Cos sequences are single stranded sequences of DNA, which have been split from the parent molecule by a specific restriction enzyme in such a way that the ends have specific affinity for each other, and hence are known as cohesive ends. A restriction enzyme (or restriction endonuclease) is an enzyme that cuts double-stranded DNA. The enzyme makes two incisions, one through each of the phosphate backbones of the double helix without damaging the bases. ...

These DNA-Sequences make it possible to pack genes with up to 40K base pairs, while normal plasmids are able to carry only 10-15K base pairs. Cosmids are packeted in phagestructures consisting of proteins, which allows the foreign genes to be inserted into the bacteria. If the Cosmids contain, for example, genes for resistance against antibiotics, the transfected bacteria are then able to survive and to spawn in a nutrient solution containing the antibiotic. Cosmids can be used to build genomic libraries. Headline text this website sucks your mothers dickIn molecular biology, two nucleotides on opposite complementary DNA or RNA strands that are connected via hydrogen bonds are called a base pair (often abbreviated bp). ... Headline text this website sucks your mothers dickIn molecular biology, two nucleotides on opposite complementary DNA or RNA strands that are connected via hydrogen bonds are called a base pair (often abbreviated bp). ... In molecular biology, a library is a collection of molecules in a stable form that represents some aspect of an organism. ...

References

• Bruce A. Voyles (2002) The biology of viruses 2nd ed. ISBN 0-07-237031-9
• Stryer, Lubert (1995) Biochemistry 4th ed. ISBN 0-7167-2009-4