Transcription of eukaryotic genes can be repressed in various ways. These include the four mechanisms

1. Competition	a-Repression is caused by recruiting histone modifiers that alter nucleosomes in ways that inhibit transcript
2. Inhibition	b-A repressor binds to a site on DNA beside an activator and interacts with that activator, occluding its activating region
3. Direct repression	c-By binding to a site on DNA that overlaps the binding site of an activator, a repressor can inhibit binding of the activator to a gene and thus block activation of that gene.
4. Indirect repression	d-A repressor binds to a site upstream of a gene and, by interacting with the transcriptional machinery at the promoter in some specific way, inhibits transcription initiation.

#Question id: 2788

#Unit 2. Cellular Organization

DNA that is transcriptionally active

#Question id: 5583

#Unit 5. Developmental Biology

In mammals, dosage compensation is carried out by:

#Question id: 2903

#Unit 2. Cellular Organization

There are five known families of enzyme complexes that actively move or displace nucleosomes, hydrolyzing ATP in the process, three of which are particularly important in transcriptional activation. Which of the following statement is/are correct regarding these nucleosome remodeling complexes?

I. SWI/SNF remodels chromatin so that nucleosomes become more irregularly spaced, and stimulate the binding of transcription factors. It includes a bromodomain near the C-terminus of the active ATPase subunit, which interacts with acetylated histone tails.

II. Some members of a family, SWR1, are involved in deposition of the H2A.Z histone variant in transcriptionally inactive chromatin. 

III. NURF, a member of the ISW1 family, remodels chromatin in ways that complement and overlap the activity of SWI/SNF. These two enzyme complexes are crucial in preparing a region of chromatin for active transcription.

#Question id: 18942

#Unit 13. Methods in Biology

#Question id: 16318

#Unit 7. System Physiology – Animal