(show all your works and measure that you answer all questions for part a to par
ID: 178130 • Letter: #
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(show all your works and measure that you answer all questions for part a to part b below. Sorry for long questions, but I give thanks to anyone who can help me)
You are a medical doctor and two of your patients are a pair of identical twins. One of twins has type 2 diabetes, while other doesn't. You believe that this may be due to differences in the gene PPARG, which is necessary in order for the pancreas to release insulin. Patients with type 2 diabetes often have reduced expression of the PPARG gene. Since your patients are identical twins, with the same genes, how can they have different expressions of the PPARG gene? b. Will the twin with diabetes have more euchromatin or heterochromatin in the region with the PPARG gene? What type of chemical tag can use this?Explanation / Answer
Answer a. Since twins share all of their DNA, any allele-specific differences in expression between them can't be explained by genetic sequences and must be due to environmental factors. Environmental factors, including smoking habits, physical activity levels and diet, can influence epigenetic patterns and may help explain how the same genotype can be translated in different ways. In the given case, the different expression levels of PPARG gene in the identical twins is due to epigenetic differences. In particular, variation in methylation pattern is well known to play a key role in modulating gene expression levels. Chromatin with high levels of DNA methylation is known as heterochromatin and is conducive for gene silencing. In contrast, Euchromatin exhibits lower levels of DNA methylation, relative to heterochromatin and contains most actively transcribed genes.
Answer b. The variation in gene expression in diabetic twin is due to higher level of heterochromatin as compared to normal twin. The chemical tag is DNA methylation.
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