Midterm2Key.y12 - PLANT BIOLOGY 113 SPRING 2012 MIDTERM#2...

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P LANT B IOLOGY 113, S PRING 2012 M IDTERM #2 P AGE 1 M AY 24, 2012 NAME KEY MIDTERM #2 - 250,000 POINTS TOTAL. Closed book exam due at the end of class. You may use notes handwritten on one side of a 4" x 6" card. Put your name on the card and turn it in with your exam. Please be sure that you have 6 pages. Some examples are hypothetical. Good luck! Please write your name and number on each page and sign the statement below. I did not consult with anyone or use any resource other than the notecard described above to complete this exam. I can and will explain my answers to exam questions if asked to do so. I understand that I am operating under the UC Davis Academic Code of Conduct. Signature________________________________________________________________________ QUESTION 1A (14,000 POINTS) : What genes in a wild type Agrobacterium tumefaciens Ti plasmid are expressed in a plant cell of a crown gall tumor. Briefly state how expression of each gene in a crown gall tumor benefits Agrobacterium. 1. TMS genes, tryptophan monooxygenase and indole acetamide hydrolase, TMR gene, DMA transferase, and opine synthase gene (6,000 points). 2. Opine synthase produces opines which serve as “food” for Agrobacterium. Opines also induce recombination and conjugation which increases the genetic diversity of the population. TMS and TMR genes encode hormone biosynthetic enzymes. Altering hormone concentrations induces proliferation and increases the number of plant cells producing opines (6,000 points & 2,000 points for no extra genes). 3. Agrobacteria love it! QUESTION 1B (14,000 POINTS) : Where is the (mature) T-complex formed? What proteins are part of the T- complex? What is the function of these proteins? 1. In the cytoplasm of the plant cell (4,000 points). 2. VirD2 and VirE2 (6,000 points). 3. VirD2 is part of the T-strand, covalently attached at the 5' end of the single stranded DNA. VirE2 is a single stranded binding protein that coats the single stranded DNA, possibly protecting the DNA from degradation. Both VirD2 and VirE2 have nuclear localization sequences that targets the T-complex to the nucleus (4,000 points). QUESTION 1C (14,000 POINTS) : Why is the NPT II gene often inserted into the T-DNA to generate transgenic plants? How is this bacterial gene expressed in plant cells? 1. NPTII (neomycin phosphotransferase II) is a gene that confers resistance to the bacterial protein synthesis inhibitor, kanamycin. A chimeric gene encoding NPTII is included in the T-DNA of plant transformation vectors so that transgenic plants can be selected on the basis of their resistance to kanamycin (7,000 points). 2. The protein coding region of the bacterial NPTII gene must be fused with a promoter and a terminator from a plant gene in order for it to be expressed in plants (7,000 points).
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