10

Consider that: RNA polymerase (RNAP) is a large complex (~400 kDa in bacteria); inertia and drag would hinder its rotation. RNAP is attached to its RNA transcript, which becomes increasingly large as transcription proceeds thus increasing inertia and drag. Additionally, if RNAP were to begin to rotate around DNA, the transcript could begin to wrap around ...


9

In complex eukaryotes like humans, alternative splicing is the rule, rather than the exception. Eukaryotic splicing is managed by a complex regulatory system, including more than 100 different elements, some of which are enhancers and regulators. Thus, while one form will often be dominant, one should generally expect at least some alternatives to be present ...


6

I prefer a conceptual distinction rather than a mnemonic in this case. I've always thought of a transcript as an exact copy of record - that's the meaning of the word in English, and an RNA transcript is effectively an exact copy of the DNA message. Sure, there are complications like the uracil in RNA, and that the strand that is actually copied from has the ...


2

Provirus of HIV makes a 9kb pre-mRNA which can go under alternative splicing to produce a variety of different mRNAs. Therefore alternative splicing in this infected cell can happen at the same time. I do not recall any cases of such behaviour for normal cells, off the top of my head but it must exist. Probably, alternative splicing in the same normal cell ...


2

No, it is a completely different thing, which has to do with splicing and alternative splicing. I refer you to some genetics text for details on splicing and alternative splicing, but I will give here a very brief and incomplete explanation fo what they are and how they fint into DTU. Genes are composed of introns and exons. Exons are the only parts of genes ...


2

In attempting to answer questions about protein structure, the first port of call (which one might expect the questioner to have also visited) is the Protein Data Bank — the global repository of such structures. There one can search for RNA Polymerase II CTD, look for complexes with other proteins, find recent publications in which they are reported, and ...


2

A repressor inhibits transcription, thus one expects low transcription when the repressor is present. Thus, if a protein acts as a repressor when it binds arabinose, then when arabinose is present the protein will inhibit transcription. In the typical synthetic case of AraC and pBAD, AraC+arabinose does not act like a repressor, but an activator of pBAD. ...


1

Your question is a good one, and has given rise to decades of intensive research, which continues today. The short answer is that many factors are involved, ranging from sequences within the gene up to chromatin-level changes. De Conti et al. in their review "Exon and intron definition in pre-mRNA splicing" (2012 DOI: 10.1002/wrna.1140) note: Most ...


1

If I understand your question correctly, you want to know if gene copy number can have an indirect effect on transcription, i.e. an effect that does not arise from the dosage effects of the copied sequence or the direct disruption of proximal genes? I think the answer is yes, insomuch that CNVs can change chromatin architecture. In many eukaryotes, the ...


1

The authors of The omnistat: A flexible continuous‐culture system for prolonged experimental evolution report on an experiment where they evolved Lactococcus lactis to have an anticipatory response to their environment. A culture was set up in their bioreactor, and periodically one of two weak bases was introduced: either lactate or acetate, and then, ...


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