MT1 Spring 2011

MT1 Spring 2011 - PLANT BIOLOGY 113 SPRING 2011 NAME NUMBER...

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P LANT B IOLOGY 113, S PRING 2011 M IDTERM #1 P AGE 1 A PRIL 21, 2011 NAME & NUMBER KEY HARD COPY OF ANSWERS IS DUE BY 5 PM, FRIDAY, APRIL 22 IN THE PLANT BIOLOGY OFFICE, 1002 LS (note - the office is closed between noon and 1 pm and promptly at 5 pm). You can use your notes, the course website, and text only - no Wikipedia or other sources. YOU MAY NOT CONSULT WITH ANYONE OTHER THAN THE INSTRUCTOR AND TAs ABOUT THIS EXAM - you are operating under the UC Davis Code of Academic Conduct. Please be sure that you have 6 pages. Some of the examples are hypothetical. Please write your name and number (on the website and sent to you by e-mail) on each page. 275,000 POINTS TOTAL. QUESTION 1 (18,000 POINTS) : Why must plants be able to respond to changes in their environment? Name three environmental stimuli to which plants respond. 1. Plants are sessile organisms and unable to move to escape environmental conditions. Therefore, they must adapt to environmental stress (12000 points). 2. Light, temperature, drought, gravity, touch (6000 points). QUESTION 2 (18,000 POINTS) : How do you define a gene? Based on your definition, are the promoter and introns part of a gene? Briefly, explain your answer. 1. (a) A heritable unit located in a particular region of a chromosome that determines a particular characteristic of an organism OR (b) transcribed region of the genome between DNA sequences corresponding to the 5’ and 3’ ends of the mRNA 12000 points). Other definitions are possible. 2. (a) Promoters and introns would be considered part of a gene because mutations in regions of both could lead to mutant phenotypes OR (b) promoters would not be part of a gene but introns would be part of a gene (6000 points). Question 3. You are interested in characterizing the organization of the genome of the sugar cane plant and do the following experiments. E XPERIMENT A: First, you prepare a genomic library that consists of 15 kb fragments of the sugar cane genome. You pick 100 clones at random, isolate the 15 kb genomic DNA fragments from these clones, label the fragments with radioactivity, and hybridize each fragment individually with a gel blot of sugar cane genomic DNA. The following results are obtained. H YBRIDIZATION WITH 15 KB G ENOMIC DNA F RAGMENTS 10 clones with pattern A 80 clones with pattern B 10 clones with pattern C QUESTION 3A (18,000 POINTS) : On the basis of this experiment alone, what can you conclude about the fraction of the sugar cane genome that consists of highly repeated, moderately repeated and single (or low) copy DNA? Explain and qualify your answer. 1. 10 of the clones contain at least some highly repetitive DNA, and 80 of the clones contain at least some moderately repetitive DNA, although it is not clear if these clones also contain single copy DNA. Therefore, <10% of the genome contains highly repetitive DNA and <80% of the genome contains moderately repetitive DNA (12000 points).
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  • Spring '12
  • Harada
  • DNA, single copy DNA