A bacterial culture contains 108 cells/ml in the beginning. Two hours later, it was found to contain 10¹² cells/ml. Calculate the doubling time.

A. Neomycin selects for the survival of embryonic stem cells (ES) that have incorporated the mutant gene X anywhere in the genome B. Neomycin selects for the survival of ES cell that have incorporated the mutant gene in the place of the wild-type gene C. Neomycin prevents Candida infection during ES cell culture that does not have gene X D. Neomycin makes the gene X knock-out mice resistant to Candida infection

A. Remove large proteins B. Remove collagen only C. Remove mycoplasma and microorganisms D. Remove foaming agents

A. Hold the pH at 5.6 B. Hold the pH at 7.5 C. Add calcium salt first and then phosphate source D. None of the above

A. Introduce foreign DNA into a gamete or fertilized ovum B. Inject a gene of interest into a somatic cell C. Inject a gene of interest into several somatic cells D. Introduce foreign DNA into somatic cells in culture and transplant them