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43 votes
Accepted

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 ...
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38 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 ...
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17 votes
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Why deoxyribose for DNA and ribose for RNA?

Nice question which leads to the fundamentals of DNA and RNA. DNA (Deoxyribonucleic acid) is the core of life in Earth, every known living organism is using DNA as their genetic backbone. DNA is so ...
  • 1,874
17 votes
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What is the explanation for the smaller number of tRNA than codons?

Th reason for this is that for the third base of the tRNA non-Watson-Crick pairing is allowed. This phenomenon is called "Wobble base pairing". See the figure (from here) for illustration (from here): ...
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17 votes

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 ...
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15 votes
Accepted

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 ...
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 ...
  • 537
14 votes

First RNA polymerase-mRNA

The RNA world hypothesis states that self-replicating RNA (that is, an autocatalytic RNA polymerase) was the first form or precursor of life. So, in that context, your question is basically asking how ...
  • 17.5k
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 ...
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12 votes
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Are codons that map to the same amino acids interchangeable?

I think given that you're just getting started with genetics, you can say that the codons are interchangeable. This is generally true, though not technically correct. Here are a few reasons for why ...
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12 votes
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Can DNA & RNA be considered as nature's programming language?

This question can't be answered with a simple yes/no, but I would say that the analogy of DNA being the "code" used by cells is a reasonable one, if taken with a number of other considerations. DNA ...
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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 ...
11 votes
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How many RNA-binding proteins can simultaneously bind on a single mRNA?

See this paper. They have studied RBP-protected sites in the entire human transcriptome by RNA-protein crosslinking followed by RNAse digestion and sequencing: PIPseq. Figure 1 of the paper shows ...
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9 votes
Accepted

What's the longest transcript known?

Top 10 long processed transcripts in humans (with multiple isoforms), from gencode 19 annotations: ...
  • 35.1k
9 votes

Why deoxyribose for DNA and ribose for RNA?

Addition to Jvrek's answer based on the comments. Most RNA degradation mechanisms catalysed by different RNAses (RNAse-A and RNAse-S, for example), involve the 2'-OH. Therefore the repertoire of ...
  • 35.1k
9 votes
Accepted

Where do amino acids get attached to tRNA and where is it synthesized?

A pre-tRNA is transcribed from tRNA genes in DNA by RNA polymerase III. Processing occurs in the nucleus, where a 5' sequence is cleaved by RNase P, the 3's CCA motif is added, and ~10% of the ...
  • 8,051
9 votes

Why is DNA double stranded and RNA single stranded?

Though this is a basic question (a few google searches will provide all answers) and you have asked a lot of questions, I shall answer them one-by-one. Why is RNA single stranded (and not double ...
9 votes
Accepted

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 ...
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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 ...
  • 22.7k
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 ...
  • 22.7k
7 votes
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Mutation That Loses Stop Codon

No, this will not happen. mRNAs are inspected in the nucleus before they are exported into the cytoplasm (at least in eukaryotes), where transcription and translation don't happen at the same place. ...
  • 49.4k
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. ...
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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. ...
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7 votes

Who created the codon wheel chart (not as a table)?

It is very difficult to answer this one for certain but I think the codon wheel representation is sometimes attributed to Rosemarie Swanson who represented the amino acid code using Gray code (or ...
  • 1,469
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 ...
  • 22.7k
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 ...
  • 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 ...
  • 22.7k
6 votes

What's the longest transcript known?

I think a good candidate is the human titin gene. The gene itself has 363 exons, depending on the isoform it has between 27.000 and 34.000 residues. This makes up a processed mRNA length of up to ...
  • 49.4k
6 votes

How many water molecules will be generated when single nucleotides are used to make this RNA: 5’-UUAACCGUCAG-3’?

It's one for every phosphodiester bond formed. 11 nucleotides, but only 10 bonds needed to join them into an oligonucleotide: ...
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6 votes
Accepted

How to find miRNA binding sites on a specific gene?

There are some tools for predicting the binding: TargetScan (based on seed match [primary], extra pairing, sequence context 1 — nucleotide composition around the site etc [secondary]) miRanda (based ...
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