Gene Expression Answers

Answer B. Gene expression is initially low because glucose is present and keeps the cAMP level low. At point A, glucose was depleted (answer not given as option), allowing the cAMP to increase. 

Answer B, Inheritance only from affected females strongly suggests a defect in a mitochondrial gene. Defects in mitochondrial gene expression phenotypkaUy present as problems in nerves and/or muscles, tissues with high aerobic metabolism. 

Van Gelder We are currently making the JLdjBmal mice to answer that question. Rae Silver has some results relating to this. She has looked for clock gene expression in the melanopsin-positive ganglion cells. Remarkably, she does not find Per expression in those cells. 

As effect parameters studied in in vitro assays become more refined, the question becomes more important of how to interpret the findings in terms of toxicity. For example in transcriptomic experiments, very low exposures in the EST which do not affect cellular endpoints of proliferation and differentiation can be shown to affect gene expression (46). The question arises at what level of response the observed effect reaches the level of adversity. Evidently, many physiologic responses are beneficial, neutralizing the hazard by homeostatic control and therefore not all detectable responses should be characterized as toxic or adverse. It may not even be possible to answer this question on the level of an individual test, but this may require a more integrated approach using weight of evidence over a combination of results from different assays. 

I win, B. Chromatin and gene expression constant questions, but changing answers (1994) Cell 79, 397-406... 

Correct answer = E. Microarray analysis allows the determination of mRNA production (thus, gerie expression) from thousands of genes at orice. A northern blot only measures mRNA production from one gene at a time. Western blots and ELISAs measure protein production (also gene expression), but only from one gerie at a time. Southern blots are used to analyze DNA not gene expression. 

Although the genetic and biochemical studies on the action of repressor on the lac operon answered many questions about gene expression of the lac operon, they left equally important questions unanswered. It had been known since the turn of the century that the lac operon expresses at a... 

As we have previously outlined, histones are small nuclear proteins that contribute to pack the DNA within nucleosomes (7,33). Histones are subject to a number of covalent post-translational modifications that collectively influence chromatin remodeling and gene expression. The question now is how to build genome-wide histone-maps. The answer came recently thanks to the combination of ChIP followed by either microarrays (ChIP-chip) or sequencing methods (ChIP-Seq) (31). 

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