Three defined steps in a transcription cycle; choose correct one

1a. Closed complex	In this form, the DNA remains double-stranded, and the enzyme is bound to one face of the helix. I
1b. Open complex	In which the DNA strands separate over a distance of 13 bp around the start site to form the transcription bubble. In the next stage of initiation,
2. Promoter escape	Incorporation of the first 10 or so ribonucleotides is a rather inefficient process, and at that stage, the enzyme often releases short transcripts and then begins synthesis again
3. Initial transcribing complex.	Once an enzyme makes a transcript longer than 10 nucleotides, it is said to have

#Question id: 4112

#Unit 3. Fundamental Processes

Which of the following is the structure of the nucleotide at the branch site of a spliced intron?

#Question id: 4113

#Unit 3. Fundamental Processes

Match the transcriptional machinery with their respective RNA Polymerase

#Question id: 4114

#Unit 3. Fundamental Processes

Splice-site recognition is prone to two kinds of errors. First, splice sites can be skipped, with components bound at, for example, a given 5’ splice site pairing with those at a 3’ site beyond the correct one. Ways in which the accuracy of splice-site selection can be enhanced are as

A. The factors that recognize that site are transferred from the polymerase carboxy-terminal “tail” onto the RNA. Once in place, the 5’ splice site components are poised to interact with those other factors that bind to the next 3’ splice site to be synthesized.

B. SR (serine–arginine-rich) proteins bind to sequences called exonic splicing enhancers (ESEs) within the exons. SR proteins bound to these sites recruit the splicing machinery to the nearby splice sites to ensure correct splicing

C. By recruiting splicing factors to each side of a given exon, this process encourages the so-called “exon definition, contribute to correct splicing

D. Alternative splicing is intentional missplicing mechanism

Which of the following is INCORRECT?

#Question id: 4115

#Unit 3. Fundamental Processes

The possible type of splicing outcome of given gene construct will be

#Question id: 4116

#Unit 3. Fundamental Processes

Proteins that regulate splicing bind to specific sites called exonic (or intronic) splicing enhancers (ESE or ISE) or silencers (ESS and ISS). The former enhances, and the latter repress, splicing at nearby splice sites. Examples of splicing activator and repressors are as

#Question id: 4117

#Unit 3. Fundamental Processes

The RNA recognition motif (RRM), also called the RNP motif and the RNA-binding domain (RBD), is the most common RNA-binding domain in hnRNP proteins. Choose important characteristics of RBD

a. RRM domain consists of a four-stranded b sheet flanked on one side by two a helices.

b. To interact with the negatively charged RNA phosphates, the b sheet forms a positively charged surface

c. The 45-residue KH motif is also found in the hnRNP and several other RNA-binding proteins

Which of the following statements are correct?