Suppose the experiment of Meselson and Stahl was performed on a sample of 8 cells, each containing one copy of its circular double-stranded DNA genome, and that had been growing on normal   14N medium. You then grew the cells for 3 generations in medium containing   15N. The outcome would be             A)   8 cells with single-stranded DNA molecules with   14N, and 24 cells with single-stranded DNA molecules with   15N.                 B)   16 cells with double-stranded DNA molecules with equal amounts of   14N and   15N, and 48 cells with double-stranded DNA molecules with   15N.             C)   8 cells with double-stranded DNA molecules with equal amounts of   14N and   15N, and 24 cells with double-stranded DNA molecules with   15N.             D)   8 cells with double-stranded DNA molecules with equal amounts of   14N and   15N, and 32 cells with double-stranded DNA molecules with   15N.             E)   65 cells with single-stranded DNA molecules with   15N.

You have ligated a foreign DNA fragment into the EcoRI site in multiple cloning site of pUCI18. You then transform how E.coli with the ligation mixture. Some of the bacterial colonies growing on the nutrient agar plate that contains ampicillin and Xgal are white and some are blue. Bacterial colonies that are white a) contain recombinant plasmid DNA b) have hydrolyzed ampicillin to form a colored compound c) are untransformed bacteria d) contain non recombinant plasmid DNA

When cloning a piece of DNA, the purpose of using the LacZ blue-white colony method is to A) Remove bacteria that do not have recombinant vectors B) Remove bacteria that do not have the DNA insert of interest Remove linear DNA Distinguish colonies that have recombinant vectors from those with non-recombinant vectors. E) Remove bacteria that have not taken up the vector

What is the role of the liquid detergent used in the experiment?  a) It allows the DNA to unwind. b) It aids filtration. c) It helps break down the cell membrane. d) It helps keep the DNA soluble in solution.

You isolated two bacteria from soil that you assumed were different species since they have different properties - for example, one is resistant to several antibiotics and the other is not. However, upon sequencing the 16S rRNA genes of the isolates, you have discovered that they are the same genus and species. When you extract the total DNA from each and run a gel, you discover the resistant strain has a plasmid in addition to the primary Chromosome. a. How might this strain have acquired the plasmid? b. What is definitely encoded on the plasmid given the information provided? c. How could you use fluorescence microscopy to determine if other bacteria in your soil suspension are carrying the same plasmid? Be sure to comment on the type of fluorescent probe, how it will interact with your sample, and how you will distinguish cells harboring the plasmid from the rest of the population (what will it look like).

We transformed E coli cells with a plasmid modified to contain a ‘virulence factor’ which would allow growth on media containing the antibiotic kanamycin (Kan). The plasmid confers constitutive resistance to ampicillin (Amp). Assume you were given competent cells of known transformation efficiency (TE).  Assume TE= 1x10[7] (note 10[7] means 10 to the power of 7). You want to have about 1000 colonies on the P-200 plate. How many nanograms of plasmid should you use in the transformation reaction? Select only one answer.   1. 0.05   2. 20.00   3. 0.50   4. 50.00   5. 200.00   6. 5.00

Answer part C of the following: A) E. coli DNA and binturong DNA are both 50% G-C. If you randomly shear E. coli DNA into 1000 bp fragments and put it through density gradient equilibrium centrifugation, you will find that all the DNA bands at the same place in the gradient, and if you graph the distribution of DNA fragments in the gradient you will get a single peak (see below). If you perform the same experiment with binturong DNA, you will find that a small fraction of the DNA fragments band separately in the gradient (at a different density) and give rise to a small "satellite" peak on a graph of the distribution of DNA fragments in the gradient (see below). Why do these two DNA samples give different results, when they're both 50% G-C? See graph B.    B) If you denatured the random 1000 bp fragments of binturong DNA that you produced in question 1a by heating them to 95ºC, and then cooled them down to 60ºC and allowed them to reanneal, you would find that approximately 15% of the…

If you use the pUC18 vector  to clone in the MCS region, predict the following: a) Do bacteria that are blue in color have a cloned insert? b)Do bacteria that are white in color have a cloned insert?  c) If you were to grow these cells on Chloramphenicol (an antibiotic), would the bacteria with the pUC plasmid grow? Why or Why not?

An Hfr strain that is leuA+ and thiL+ was mixed with a strain thatis leuA− and thiL−. In the data points shown in the following graph,the conjugation was interrupted at different time points, and thepercentage of recombinants for each gene was determined bystreaking on a medium that lacked either leucine or thiamine.What information do you know based on the question and your understanding of the topic?

In transformation, a bacterial cell takes up DNA fragments from its surroundings. The figure shows the process of natural transformation. Position the labels below with the correct images. (A) Donor and recipient genomes The donor strand is integrated into the recipient chromosome and the displaced bacterial DNA is degraded. A wild-type donor cell is in the vicinity of a double auxotroph. If the wild-type cell lyses, it releases DNA into the environment. One cell is identical to the original recipient, while the other carries the wild-type genes. A competent recipient cells a receptor site on its surface. One strand of donor DNA enters the cell and pairs with a homologous region of the bacterial chromosome The remaining DNA strand is degraded. A donor DNA strand binds to the receptor site. Reset trpC1 Wild-type donor cell Mechanism of natural transformation Donor DNA hal Receptor site- trpc/his double auxotroph Recipient cell Competent cell recipient -Bacterial chromosome (had.bpC") Ma…