7. A. You are studying the transcription of a set of genes that produce a protei

Question

7. A. You are studying the transcription of a set of genes that produce a protein that darkens fur. So far you have been looking at mRNA levels in the cell, but now you're interested in the levels of the DNA binding to nucleosomes. Would you expect the nucleosome packing to be higher or lower in genes that are being transcribed?. B. You notice that some of your mice are born with very pale fur. Would this be caused by increased or decreased expression of your gene? List two changes in your gene that could be causing this. C. How could you determine if this change in gene expression was genetic or epigenetic?

Explanation / Answer

7A. Given information,

A gene is responsible for dark fur in mice. Chromatin has to be in loosely condensed state for a gene to be expressed so that RNA polymerase can bind and transcribe the gene. Since the gene is expressed, the chromatin must be in the euchromatin state.

B. WT gene is responsible for dark fur. i.e. expression of the gene causes black fur.

If mice show pale fur, it means that they are not expressing the gene.

C. Epigenetic modifications: These modifications alter the recruitment of RNA polymerase to the gene locus by changing the compactness of the chromatin. Ex: Histone modifications and DNA methylation.

If the change in gene expression is due to a mutation in the DNA sequence, we can find it by DNA sequencing.

Epigenetic changes do not alter the gene sequence. So, if we do not find changes in DNA sequence and the mice still show pale fur, it could be due to epigenetic changes.

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