12A. Which of the following proteins is likely to act as a gene repressor? (a) f
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Question
12A. Which of the following proteins is likely to act as a gene repressor?
(a) factor X
(b) factor Y
(c) factor Z
(d) none of the above
12B. Which of the following proteins are likely to act as gene activators?
(a) factors X and Y
(b) factors X and Z
(c) factors Y and Z
(d) factor X only
12C. Experiment 1 in Figure Q8-21 is the positive control, demonstrating that the region of DNA upstream of the gene for GFP results in a pattern of expression that we normally find for the LKP1 gene. Experiment 2 shows what happens when the sites for binding factors X, Y, and Z are removed. Which experiment above demonstrates that factor X alone is sufficient for expression of LPK1 in the kidney?
(a) experiment 3
(b) experiment 5
(c) experiment 6
(d) experiment 7
12D. In what tissue is factor Z normally present and bound to the DNA?
(a) kidney
(b) liver
(c) heart
(d) none of the above
You are interested in understanding the gene regulation of Lkpl, a protein that is normally produced in liver and kidney cells in mice. Interestingly, you find that the LKPI gene is not expressed in heart cells. You isolate the DNA upstream of the LKPI gene place it upstream of the gene for green fluorescent protein (GFP), and insert this entire piece of recombinant DNA into mice. You find GFP expressed in liver and kidney cells but not in heart cells, an expression pattern similar to the normal expression of the LKPI gene. Further experiments demonstrate that there are three regions in the promoter labeled A, B, and Cin Figure Q8-21, that contribute to this expression pattern. Assume that a single and unique transcription factor binds each site such that protein X binds site A, protein Y binds site B, and protein Z binds site C. You want to determine which region is responsible for tissue-specific expression, and create mutations in the promoter to determine the function of each of these regions In Figure Q8-21, ifthe site is missing it is mutated such that it cannot bind its corresponding transcription factor. expression in experiment promoter region for LKP1 liver? kidney? heart? GFP yes yes no no yes no no yes yes yes yes no no no no yes yes yes no yes no yes no no Figure Q8-21Explanation / Answer
12A)option c -factor Z is gene repressor.Z is a repressor protein and represses transcription in the heart.
12B) option a-factors X and Y
Factors X and Y are activators.Factor X binds to the "A" enhancer element to activate transcription in the kidney and factor Y binds to the "B" element to activate transcription in the liver.
12C)option a-experiment 3
When the "A"element is present,X factor can activate transcription of the LKP in kidney.When it is absent (experiments 5 & 8),transcription in the kidney does not occur.This happens regardless of the presence of the "B"element (experiment 6) or the "C"element (experiment 7).When the "B"element is present,Y factor can activate transcription of the LKP in liver.When it is absent (experiments 3,5 & 7),transcription in the liver does not occur.This happens regardless of the presence of the "A"element(experiment 6) or the"C" element(experiment 8).
12 D)heart
Factor Z is normally present in heart tissue and bound to the "C"DNA element to repress transcription of the LKP gene in the heart.Whenever the “C” element is present (experiments 5,7 & 8),transcription in the heart does not occur.When it is absent,transcription in the heart does occur.
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