1 how many bacteria do you have to start with to obtain enou

1) how many bacteria do you have to start with to obtain enough DNA to detect that gene? assume 50% efficiency of extraction.

2) why do people want to \"clone DNA\"?

Solution

1) Number of bacteria depends on which strain of bacteria is used for DNA extraction. Over night incubation of plates at 37⁰ C for E. coli gives around 30-300 colonies per plate which are sufficient for further culturing.

But to detect gene of interest, the DNA obtained from them must be of high purity and quality. About 10⁴ copies of target DNA are required to detect gene of your interest in 25-30 PCR cycles. For this you would need 1ng - 1 ug genomic DNA template which has high purity. Therefore, even if extraction process provides 50% efficiency but purity of DNA is good, proceed with PCR reaction to amplify the targetted gene of interest.

2) Cloning is a process to make copies of DNA which are used for many genetic engineering approaches. Some of them are - a) cloning of desired gene helps in identifying the expression of that gene in various tissues like in plant and animal tissues.b) Cloning of genes also help in sequencing to identify desired gene of interest. c) Organisms which have difficulty or are slow to breed normally can be reproduced quickly by means of cloning.