Gene expression is controlled by a number of features：练习题

Which statement best describes the difference between totipotent and pluripotent stem cells in mammals?

Which of the following best explains how induced pluripotent stem cells (iPS cells) are created from adult somatic cells?

Epigenetic changes can inhibit the transcription of genes. Which combination of chemical modifications to DNA and histones would most likely lead to the silencing of a gene?

Oestrogen is a steroid hormone that regulates gene expression. Which of the following best describes its mechanism of action in initiating transcription?

Epigenetic regulation involves changes in gene function without altering the DNA base sequence. Which of the following environmental factors would most likely lead to the inhibition of transcription?

In some eukaryotic organisms, the translation of mRNA can be inhibited by a process known as RNA interference (RNAi).
What is the specific role of the enzyme complex in this process once it has bound to a target mRNA molecule?

Oestrogen is a steroid hormone that can initiate the transcription of specific target genes in eukaryotes.
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}Describe the sequence of events that occurs after oestrogen enters the cell, explaining how it leads to the initiation of transcription.

The methylation of DNA is a key epigenetic mechanism.
Describe the specific mechanism by which increased methylation of cytosine bases in a promoter region inhibits the transcription of a gene.

The control of gene expression in eukaryotes is complex and occurs at multiple levels.

a) Explain how transcriptional factors and oestrogen initiate the transcription of specific target genes.
b) Describe the mechanism of RNA interference (RNAi) in inhibiting the translation of mRNA.
c) Define epigenetics and explain how increased methylation of DNA leads to the silencing of a gene.

Gene expression can be regulated at the level of transcription through various mechanisms.

(a) Describe the role of transcriptional factors and oestrogen in initiating the transcription of a target gene. (3 points)
(b) Explain how epigenetic changes, specifically DNA methylation and histone acetylation, can lead to the silencing of a gene. (3 points)
(c) Distinguish between totipotent and pluripotent stem cells in terms of their origin and differentiation potential. (2 points)