E19 - E1 The human gene that encodes the hormone is...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
E1. The human gene that encodes the hormone is manipulated in vitro and then transformed into a bacterium. In many cases, the coding sequence of the human hormone gene is fused with a bacterial gene to prevent the rapid degradation of the human hormone. The bacteria then express the fusion protein and the hormone is separated by cyanogen bromide cleavage. E2. The plasmid with the wrong orientation would not work because the coding sequence would be in the wrong direction relative to the promoter sequence. Therefore, the region containing the somatostatin sequence would not be transcribed into RNA. E3. One possibility is to clone the toxin-producing genes from B. thuringiensis and introduce them into P. syringae. This bacterial strain would have the advantage of not needing repeated applications. However, it would be a recombinant strain and might be viewed in a negative light by people who are hesitant to use recombinant organisms in the field. By comparison, B. thuringiensis is a naturally occurring species. E4. To construct the coding sequence for somatostatin, the researchers synthesized eight oligonucleotides, labeled A–H. When these oligonucleotides were mixed together, they would hydrogen bond to each other due to their complementary sequences. The addition of ligase would covalently link the DNA backbones. The left side of the coding sequence had an Eco RI site and the right side had a Bam HI site; these sites made it possible to insert this sequence at the end of the ß -galactosidase gene. You may also notice that an ATG codon (AUG in the mRNA) precedes the first alanine codon in somatostatin. This AUG codon specifies methionine, which allows the somatostatin to be cleaved from ß -galactosidase using cyanogen bromide. This was necessary because somatostatin, by itself, is rapidly degraded in E. coli, whereas the fusion protein is not. E5. Basically, one can follow the strategy described in Figure 19.6. If homologous recombination occurs, only the Neo R gene is incorporated into the genome. The cells will be neomycin resistant and also resistant to gancyclovir. If gene addition occurs, the cells will be sensitive to gancyclovir. By growing the cells in the presence of neomycin and gancyclovir, one can select for homologous recombinants. The chimeras are identified by the observation that they have a mixture of light and dark fur. E6. A kanamycin-resistance gene is contained within the T DNA. Exposure to kanamycin selects for the growth of plant cells that have incorporated the T DNA into their genome. The carbenicillin kills the A. tumefaciens. The phytohormones promote the regeneration of an entire plant from somatic cells. If kanamycin were left out, it would not be possible to select for the growth of cells that had taken up the T DNA. E7. 1.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/07/2009 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas.

Page1 / 4

E19 - E1 The human gene that encodes the hormone is...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online