Recombinant DNA technology involves a host and a vector. The host allows the recombinant DNA to propagate and express.

rDNA is formed when a target gene (insert) is combined with a vector and introduced into a host organism.

E. coli reproduces rapidly, doubling its population every 20 minutes, making it efficient for gene cloning.

A good vector should be small, possess an origin of replication, unique restriction sites, and a selectable marker.

Plasmids are circular, double-stranded DNA used as vectors that can replicate independently within a host cell.

High-copy plasmids replicate independently of the host's chromosomal DNA, allowing 10-30 copies per cell. Low-copy plasmids are restricted to 1-2 copies per cell.

Selectable markers, such as antibiotic resistance genes, are used to identify which cells have taken up the vector.

λ phage is a bacteriophage that can efficiently clone large inserts of DNA and is easy to propagate.

Cosmids are hybrid vectors that combine features of plasmids and λ phage, allowing for the cloning of larger DNA inserts (up to 45 kbp).

Yeast Artificial Chromosomes (YACs) are vectors designed for cloning large DNA fragments (200-500 kbp) in yeast.

Expression vectors not only carry DNA inserts but also facilitate their expression in the host, containing promoters and terminators.

Shuttle vectors can replicate in both prokaryotic and eukaryotic cells, allowing for versatile application in gene cloning.

Heterologous gene expression refers to expressing a gene from one organism in a different organism, often requiring specific conditions.

R-plasmids are a type of plasmid that carry antibiotic resistance genes, providing a survival advantage to bacteria.

Episomes are plasmids that can integrate into the chromosomal DNA of the host cell.

Cosmid vectors are plasmids that have been modified to include lambda phage sequences, facilitating the cloning of larger DNA segments.

Plasmid vectors are modified to contain specific sequences, such as multiple cloning sites, to increase functionality for gene cloning.

Phasmids are hybrid vectors that combine properties of both plasmids and phage, retaining the ability to replicate like both.

Cos sequences allow for the efficient packaging of DNA into the lambda phage capsid, crucial for cloning operations.