Pseudomonas has a plasmid containing the mer operon, which includes a gene for mercuric reductase. The enzyme catalyzes the reduction of the mercuric ion Hg2+ to the uncharged form of mercury, Hg0 Hg2+ is quite toxic to cells, Hg0 is not.
1. What condition would induce this operon to be transcribed and the transcript to be translated into the proteins including mercuric reductase?
2. The protein encoded by the mer operon binds to Hg2+ outside the cell and brings it into to the cell, why would a cell bring in a toxin?
Two daughter cells are most likely to inherit which one of the following from a parent cell?
3. a change in a nucleotide in mRNA, tRNA or rRNA?
4. Which of the following is NOT a method of horizontal gene transfer? Contrast two methods of horizontal gene transfer.
conjugation, integration of a transposon, transduction or transformtion
5. Amino acid sequences for the viral coat of HIV were sequenced from three HIV patients. Of the amino acid sequences shown which are most closely related?
Patient A Asn Gln Thr Ala Ala Ser Lys Asn Ile Asp Ala Leu
Patient B Asn Leu His Ser Asp Lys Ile Asn Ile Ile Leu Leu
Patient C Asn Gln Thr Ala Asp Ser Ile Val Ile Asp Ala Leu
Lable a-l. Remember, you will be drawing and lableing the DNA replication fork on Lecture Exam III.
9. What is the following region of DNA called and how does it work? Explain the differences between an inducible and a repressible version.
10. Fill in following concept map on types of mutations:
11. Table 8.1 on page 240 gives examples of restriction enzymes. Restriction enzymes cut double stranded DNA at specific sites, or palindromes. Restriction enzymes serve to cut up phage DNA so that bacterial chromosomes are not mixed with phage genes. Restriction enzymes do not cut bacterial DNA because of methylation. There are two groups of restriction enzymes based on the way the two strands of DNA are cut. One type leaves blunt ends and the other sticky ends. Restriction enzymes may be used to make a cut in a plasmid, a vector, and insert a gene and use ligase to connect the gene to the cut ends of the plasmid.
Give an example of one restristion enzyme that makes sticky ends and one that makes blunt ends. Explain the origin of the enzymes' names.
12. For decades researchers at Duke Medical School have worked to engineer a polio virus to treat glioblastoma. The strategy is to remove the genes of the virus that cause disease polio and replace them with genes for a cold virus, leave the genes that allow the virus to enter the glial cell, and the genes that allow the virus to lyse or destroy the cell it enters for replication. LIst and explain two 'tools of recombinant DNA technology' explained in chapter 8 that could be used to create this modified polio virus. Table 8.2 is a summary of t he tools of DNA technology. p 250.
13. A large long term study on the genomic effects of PTSD utlizes DNA microarrays to screen for changes in gene expression of subjects in the study. Some of the preliminary data has identified clusters of genes that change with stress. What about this technique allows for screening of hundreds of genes on a single glass slide? If the microarray uses cDNA, how does cDNA differ from genomic DNA? Why must the DNA on the slide be ssDNA?
14. Explain the function and use of reverse transciptase in synthesizing cDNA? How does HIV use reverse transcriptase? What drug in a cocktail (ART) used to treat AIDS targets reverse transcriptase? p.543
Please label this technique. What is the technique? Explain at least two applications.
16. PCR utilizes taq polymerase, what is the adavantage of this type of DNA polymerase? Why can't DNA polymerase from E. coli be used?
17. Why are mutagens tools of recombinant DNA technology? Give two examples of mutagens and their mode of action.
There is a market for salmon, however salmon takes three years to mature which increases the cost of salmon. AquaBounty first presented a fast growing fish in 1989 by combining a growth hormone gene from the Chinook salmon and a reglatory gene from the ocean pout to create a continouos low level of growth hormone in the Atlantic salmon. The genetically modified salmon grows in 18 months, may be grown in fish tanks near cities thus reducing the need for air transport and tank grown salmon have fever parasites. AquaBounty applied for FDA approval over 25 years ago, and in 2017 meet another hurdle to selling in the US because the FDA requires a GMO labeling, for which a program for which is under development. Canadian customers have bought 4.5 tons of this fish as of August 4, 2017.
18. Speculate about why genetically modified foods should be labled for the consumer?
19. Give at least two examples of recombinant DNA techniques that might be used to introduce genes into fish.
20. Fill in the boxes on the concept map below: