Mig1 recruits a “repressing complex” containing the Tup1 protein. This complex is recruited by many yeast DNA-binding proteins that repress transcription, including the alpha2 protein involved in controlling the mating-type specific. Tup1 also has counterparts in mammalian cells, choose correct mechanisms have been proposed to explain the repressing effect of Tup1.

I-Tup1 acts on nucleosomes either through recruiting histone deacetylases and/or by positioning a nucleosome at or near the transcription start site.

II-Tup1 interacts directly with the transcriptional machinery at the promoter and inhibits initiation.

#Question id: 27018

#Unit 10. Ecological Principles

#Question id: 34106

#Unit 2. Cellular Organization

#Question id: 4459

#Unit 3. Fundamental Processes

Give correct explanation, why RNA polymerase can initiate a new RNA chain on a DNA template without any primer?

A. Because RNA polymerase starts most transcripts with an A, and that ribonucleotide binds the template nucleotide (T) with only two hydrogen bonds.

B. The enzyme has to make specific interactions with one or all of the DNA template strand, the initiating ribonucleotide, and the second ribonucleotide—holding one (or all) rigidly in the correct orientation to allow chemical attack on the incoming NTP.

C. The structure of the open complex shows that the s region 3/4 linker interacts with the template strand, organizing it in the correct conformation and location to allow initiation.

D. Consistent with this, in experiments using an RNA polymerase containing a s70 derivative lacking this part of s, initiation requires much lower than normal concentrations of one or both of the first two ribonucleotides.

#Question id: 2147

#Unit 2. Cellular Organization

Movement of water across membranes is facilitated by proteins called:

#Question id: 19039

#Unit 13. Methods in Biology