Question

1. What are the three major differences between a cloning vector and expression vector?

Answer 1

The three major differences between cloning vector and expression vectors are as follows:

Cloning vector	Expression vector
1. These are DNA molecules which serveas vector to carry transport of foreign insert or DNA insert to a host cell. Cloning vector can be a genetically engineered DNA molecules from viruses or plasmids of bacterium etc.	Expression vectors are generally plasmids which not only carry foreign insert but also translate it into protein product.
2. Cloning vectors have elements which are necessary for their propagation and this elements are: ​​​​​​Ori - Origin of replication, from where replication of DNA would start. Multiple Cloning Sites- these are restriction sites carry DNA sequences of multiple restriction enzymes for treatment to insert a foreign DNA at this site. Hence known as Cloning site. Selectable Markers genes- These genes generally encodes for enzymes, antibiotics, or can be reported genes of a protein to select the recombinants from culture. For eg. If a cloning vector carrying a Ampicillin resistance gene but a host is ampicillin sensitive, therefore on successful transport of cloning vector the bacteria would become ampicillin resistant and hence would easily grow on ampicillin containing media. In this way you would able select the recombinants.	Expression vectors have regulatory elements essential for protein expression including Ori, selectable markers, and multiple Cloning Sites are as follows: Promoter - is a gene sequence from where transcription is initiated. Enhancer - is a gene sequence at which regulatory elements binds to change the rate of transcription. Ribosomal binding site at which ribosomes subunits binds to mRNA during translation. Start and stop codon, or ORF Transcription terminating sequence. Protein tags for recognition of target protein expression.
3. Cloning vectors are used for in-vivo amplification of DNA inserts using the host machinery. eg. Plasmid, cosmids, bacteriophages, BACs, YACs etc	Expression vectors are majorly used for protein expression study.