Molecular Biology-מעבדה רפואית
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Shown here are the regulatory regions of genes encoding Y and ΔY (top). You have cells which express the steroid hormone (X) receptor (Xrec) under the control of a constitutive promoter. Hormone-bound Xrec is a transcription activator binding to its recognition sequence XrecBS. The transcription factor Y contains a DNA-binding domain at the amino terminus that recognizes the sequence YBS and a c-terminus polyglutamine sequence. The transcription factor ΔY is the same as Y, but is missing the c-terminus polyglutamine sequence. The relative half-lives of X, Y, and ΔY are as follows t½X = 5, t½Y = 5, t½ΔY = 15. Which of the graphs best describes the rate of transcription from the Y promoter after the addition of hormone X at the time indicated?
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מיין לפי
The TAF1 subunit of TFIID is a histone acetylase. Which of the following is the most likely consequence?
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Which of the following is directed by transcription activators in eukaryotic cells such as to make DNA more accessible for the transcription machinery.
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DNA methylation-induced repression of the Dapk (Death associated protein kinase) gene has been observed in 80% of colorectal carcinomas. Increased methylation of the Dapk gene most likely occurs at which of the following?
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Which of the following is the most frequent DNA damage induced by ultraviolet light?
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During DNA replication, C sits on the template strand in the active site of the polymerase. An A is accidentally added to the 3' end of the new strand being synthesized. Which of the following repair functions will most likely remove it?
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מיין לפי
(USMLoid) A 55 year old woman comes to the clinic complaining of fatigue. Physical examination shows no abnormalities. A test for occult blood in the stool is positive. Her hematocrit is 30%. Her family history indicates that her mother her maternal grandfather, and a maternal aunt all died of colon cancer, each before the age of 60. Colonoscopy showed a mass in the proximal colon and a subsequent biopsy identified mucinous carcinoma. Karyotypes were normal. In which genes encoding components of the following functions is she most likely to bear an inherited mutation?
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You transfer wildtype E.coli from petri plates containing glucose to petri plates containing lactose. What sequence of events will occur at the lac operon promoter.?
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מיין לפי
(USMLoid) 5 different variably sized fragments of DNA upstream (5') of Human Gene Y, between +1 and -1500, were fused to the 5' end of a fragment of DNA encoding the Luciferase enzyme. The start of transcription is at +1, the root of the bent arrow. A scale is shown at top left. These reporter constructs were then transfected into a human cell line. Cytosol extracts were prepared 24 hours later and luciferase activity measured. The results are shown to the right for each construct. Which of the following segments of the 5' upstream sequence is most likely to contain an enhancer element.
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מיין לפי
(USMLoid) 5 different variably sized fragments of DNA upstream (5') of Human Gene Y, between +1 and -1500, were fused to the 5' end of a fragment of DNA encoding the Luciferase enzyme. The start of transcription is at +1, the root of the bent arrow. A scale is shown at top left. These reporter constructs were then transfected into a human cell line. Cytosol extracts were prepared 24 hours later and luciferase activity measured. The results are shown to the right for each construct. Which of the following segments of the 5' upstream sequence is most likely to contain an enhancer element.
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מיין לפי