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44 votes
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How many times has SARS-CoV-2 mutated?

This question makes a number of incorrect assumptions and I don't have time to correct them. The short answer is that the virus has mutated probably hundreds of times since it entered humans in late ...
iayork's user avatar
  • 14.3k
39 votes
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Is it possible to make a vaccine against cancer?

It is not only possible, these vaccines are in active development. Biontech (the company which developed the Comirnaty Corona vaccine) was founded to develop vaccines against cancer, Moderna is ...
Chris's user avatar
  • 51.7k
18 votes
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What stops messenger RNA from binding to itself?

It does fold on to itself. There are secondary structures in RNA and some of these secondary structures also have regulatory functions (for example, riboswitches). Some of these structures can also ...
WYSIWYG's user avatar
  • 35.6k
15 votes
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Does double stranded RNA (dsRNA) exist in eukaryotic cells?

Yes, dsRNAs are present in eukaryotic cells and regulate various biological processes. These nucleic acids are also present in the nucleus and regulate mitosis. Altering this nucleic acid could even ...
Twinkle Sheen's user avatar
15 votes

Is it possible to make a vaccine against cancer?

Might not be the answer you're looking for, but there's already a vaccine for one particular type of cancer - cervical cancer. Cervical cancer is largely caused by a virus though (HPV, Human ...
Allure's user avatar
  • 547
14 votes

Is viral single-stranded RNA in the absence of reverse transcriptase infectious?

In RNA viruses with a single-stranded genome, this RNA can be positive or negative sense. Positive sense RNA is directly translatable by a ribosome, while a negative strand RNA cannot be directly ...
Roger V.'s user avatar
  • 3,862
12 votes
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Why is thymine not incorporated into mRNA?

Nice question! But sadly, it comes under the category of questions about which we don't know everything yet. We don't yet know how RNA Polymerase differentiates between uracil and thymine while adding ...
another 'Homo sapien''s user avatar
9 votes
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Do any RNAs directly inhibit transcription

Yes there are reports of RNA directly inhibiting transcription. RNA induced transcriptional silencing (RITS) is a well known pathway in Schizosaccharomyces pombe (fission yeast). Initial ...
WYSIWYG's user avatar
  • 35.6k
9 votes
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Why is uracil, rather than thymine, used in RNA?

Regardless of the question† of which came first*, RNA or DNA, it is possible to rationalize the absence of thymine in RNA by a cost–benefit analysis. There is a cost to using thymine, so there must be ...
David's user avatar
  • 26.2k
7 votes

Why deoxyribose for DNA and ribose for RNA?

Why DNA for the genetic material? I think the correct and sufficient answer to this is the one so frequently repeated that it is difficult to find the original source. For example, G.F.Joyce wrote in ...
David's user avatar
  • 26.2k
7 votes

Why was not RNA completely replaced by DNA when the RNA world evolved into a DNA and protein world?

A related question is Why do some bad traits evolve, and good ones don't? Basically a strong selection pressure is necessary to filter out a trait. Having said that, there is no strong argument ...
WYSIWYG's user avatar
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7 votes
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Splicing and “the dominance of RNA-world”

This is a badly-worded phrase that means nothing in the context of the paragraph in which it occurs. There is no way the reader could be expected to understand it from this awful book on its own. ...
David's user avatar
  • 26.2k
7 votes
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How do aminoacyl-tRNA synthases distinguish between similar amino acids?

Aminoacyl-tRNA sythetases are highly specific to their corresponding amino acid. First, the activation site, where the amino acid binds, constitutes a complex network of intermolecular interactions. ...
adjan's user avatar
  • 2,106
7 votes

Why is the GenBank entry for the genomes of RNA viruses like coronavirus written as DNA?

It would appear that the current policy at GenBank is to represent all genomic sequences as DNA, even though this is not made explicit in any of the easily retrievable documentation on their website ...
David's user avatar
  • 26.2k
7 votes
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Why can't certain nucleoside analogs be used to label bacterial RNA?

Meng et al. actually give their explanation in the first paragraph of their results section. The main reasons for their claim are that they did not detect any labeling with 4SU or EU and that both ...
GaelC's user avatar
  • 466
7 votes
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Introns and miRNA

The answer to Question 1 is: The ribonucleases responsible for digesting removed intron RNA do not recognize the miRNA as such. They are unable to digest it because (or to the extent that) it assumes ...
David's user avatar
  • 26.2k
7 votes
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Correct description of ALDH7A1 and other genes

It's the second: The RNA transcript of the gene (before editing) has a length of 4964 bases. The use of "base pairs" is wrong in this context since the transcribed RNA has no paired bases. ...
Chris's user avatar
  • 51.7k
6 votes
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Do transcripts always start and end with exons?

Most (almost all, AFAIK) mRNAs and lncRNAs start with exons for the reasons already mentioned by David. In a typical splicing event, the nucleotide that is 5' to the splice donor site (lets call it ...
WYSIWYG's user avatar
  • 35.6k
6 votes
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RNA polymerase and DNA helicase

Disclaimer As I have pointed out in my comment, it is not clear whether the sources mentioned relate to eukaryotes or prokaryotes, assuming they are correct. I am a translation man, rather than a ...
David's user avatar
  • 26.2k
6 votes
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Why do mutations not take place in mRNA of higher eukaryotes?

The premise of the questions suggests that mutations cannot take place in the mRNAs of higher eukaryotes. To answer your question I think it is important to consider two viewpoints: First, from a ...
Dr. H. Lecter's user avatar
5 votes

To what extent is the genetic code more than just a code?

You call it a thought experiment but something like this has actually been done. Not entirely similar as they don't switch 2, but still they replace a codon. An overview: https://en.wikipedia.org/...
VonBeche's user avatar
  • 1,473
5 votes
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How much nucleoside triphosphate is required to form one peptide bond during protein synthesis?

Although the question shows considerable effort to achieve clarity, the way it is phrased as: How many molecules of nucleoside triphosphate… [does] it take to release enough energy still allows ...
David's user avatar
  • 26.2k
5 votes

Why is an initiator tRNA required, distinct from the methionine tRNA used in elongation?

I think the key to understanding this is to appreciate how different the initiation process is from the rest of translation. The 30S ribosomal subunit recognises start codons via an interaction with ...
Alan Boyd's user avatar
  • 22.8k
5 votes

Is there a double helix RNA?

Yes, double-stranded, helical RNA exists. It can occur naturally, a famous example would be Rotavirus, as well as synthetically in the lab. Please note, however, that viruses strictly speaking do ...
Johnny's user avatar
  • 1,509
5 votes
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Ribosomes producing proteins, but need proteins to be produced?

Ribosomes are the only means we know by which cells produce proteins. Consequently, all proteins are made by a ribosome, including the proteins that then become part of a new ribosome. It's never a ...
Armatus's user avatar
  • 7,670
5 votes

What makes/breaks the hydrogen bonds between DNA and RNA during transcription?

I wouldn't really say RNA polymerase is "creating" the hydrogen bonds so much as it's thermodynamics that creates them. When we talk about an enzyme "creating" a bond, what we're generally referring ...
Stephen B.'s user avatar
5 votes

What are the reasons for using oligo-dT instead of oligo-U to isolate mRNAs?

Note - This answer only covers the comparison of rA-dT (RNA:DNA) and rA-rU (RNA:RNA) duplexes, and not more exotic options involving deoxyuridine (dU) and ribothymidine (m5U). I can think of three ...
acvill's user avatar
  • 8,296
5 votes
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Does N1-methyl-pseudouridine occur naturally in any RNA?

N1-methyl-pseudouridine occurs naturally in the tRNAs of most archaea. It replaces the ribothymidine found in the TΨC-loop of eubacterial and eukaryotic tRNAs. Although the enzyme responsible for the ...
David's user avatar
  • 26.2k
5 votes

Were nicotinic acid/amide or flavin nucleotides ever part of primary RNA sequence?

There are naturally occurring RNAs that contain a NAD "cap" at 5' end (Bird et al., 2018; Wang et al., 2019). I could not find any papers on natural RNAs with nicotinamide or flavin as a ...
WYSIWYG's user avatar
  • 35.6k

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