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8 votes

Why is the codon size three, rather than four?

The reason is pretty simple: It comes from the number of amino acids used to make proteins and thus with the necessary number of possible combinations and robustness of the system. We have 20 amino ...
Chris's user avatar
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8 votes
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According to an online course, ribose and adenine can bond to make ATP. Is this true?

The structure shown is indeed of guanine, not adenine. A nucleotide is defined as being composed of a nitrogenous base, a pentose sugar and phosphate (see, e.g. the Wikipedia entry). So the simplest ...
David's user avatar
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4 votes
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Change of DNA concentration due to restriction digest?

Summary The poster wishes to know why spectrophotometric readings (presumably absorbance at 260 nm) on a sample of genomic DNA from an unspecified organism appear “slightly” greater after incubation ...
David's user avatar
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4 votes
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Overlapping atomic radii in data of experimentally observed protein assemblies

Looking at the validation report for model 6R7M, we see that there are no symmetry-related clashes listed. (Although there are two clashes within the asymmetric unit, HA of ASP20 - HD3 of PRO21 and ...
timeskull's user avatar
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4 votes
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What is the minimum Ct value that you would consider indicates no gene expression?

Can't you just do a negative control and use that to calibrate? Alternately, run the DNA from your PCR on a gel with a positive control indicating expression. Literally zero expression should mean ...
Maximilian Press's user avatar
4 votes
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What makes viruses like the flu and covid so tolerant of mutations compared to most other viruses?

This is actually a far more complex question than it might seem on the surface. It's something that has been noted for quite some time by virologists - and it isn't just RNA viruses that do this. ...
bob1's user avatar
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Open Reading Frame problem

The mistake in the original poster’s reasoning is to calculate the ORF as 906 bases. In fact, as normally defined, it is 903 bases — the amino-acid coding portion (300 x 3 = 900 bases) plus the ...
David's user avatar
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3 votes

Why do we choose to use agar instead of agarose in various microbial applications?

Agarose is indeed more expensive than agar because it is purified from agar, i.e. it is agar minus the agaropectin. Agaropectin is heterogeneous, and modified with acidic side-groups. The consequence ...
CaroZ's user avatar
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3 votes
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Best way to predict the effects of deletion mutations on protein function?

I would suggest looking at the sequence conservation of the protein domains / sequence positions of interest. One such tool that is oriented towards human genomics is CADD. This tool can provide a ...
Maximilian Press's user avatar
3 votes
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The split in Boroeutheria into Euarchontoglires and Laurasiatheria. Was this due to the opening up of the Atlantic Ocean?

It would seem the answer is "No" at the current understanding of this issue. You should understand that this is a very complex topic, which is based on both molecular (i.e. DNA sequences or ...
bob1's user avatar
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3 votes

Change of DNA concentration due to restriction digest?

As you did a clean up, then you lost some DNA in this process. There are always losses from clean up steps. Note also that spectrophotometry is notoriously unreliable for DNA quantitation; it's more ...
bob1's user avatar
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3 votes

Efficiency of molecular motors vs. human-made motors

It is referencing an out of date study poorly. The efficiency of F1-ATPase has been measured at so close to a hundred percent that the margin of error of the measurement, exceeds the difference. BUT ...
John's user avatar
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Is the 5% of the oxygen used in the breathing process fully transformed into CO2?

When you write the number "21%", it represents equally all numbers rounded to 21%; that is, 21% is the same number as 20.5% and 21.49% under the most common rounding convention. When you ...
Bryan Krause's user avatar
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3 votes

What makes viruses like the flu and covid so tolerant of mutations compared to most other viruses?

One consideration is that influenza viruses and coronaviruses are RNA viruses. While DNA viruses are generally dependent on the host's replicative enzymes, which have evolved low error rates for host ...
canadianer's user avatar
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2 votes
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Can humans metabolize D-malate?

I do not have specific proof, but I strongly suspect that the answer to this question is NO on the basis of the following arguments. The overwhelming majority of sugars, amino acids, carboxylic acids ...
David's user avatar
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2 votes

How come SSBPs in RPA don't bind primers?

From a 1994 review of E.coli single-stranded binding protein (SSBP) in Annual Reviews of Biochemistry, it would appear that at least 35 nucleotides (nt) of single-stranded DNA are required for binding ...
David's user avatar
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2 votes

Does recombination occur in both chromatid of a chromosome with homologous chromosome? Or only 1 chromatid participate in crossing over?

The diagram you provide is just a schematic, showing a simple version to clarify what is happening in a crossover. It seems that at least once crossover has to occur in each bivalent for normal ...
Charles E. Grant's user avatar
2 votes

Why are camelid-derived nanobodies called VHH (variable heavy domain of heavy chain)?

First, the definition of VHH (and VH) from the article by S Muyldermans — “Nanobodies: Natural Single-Domain Antibodies” in Annu. Rev. Biochem. 2013. 82:775–97. VHH: antigen-binding variable domain ...
David's user avatar
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What is meant by the stabilization of a receptor?

The key phrase is "to the postsynaptic membrane" which in that sentence modifies all of recruitment, trafficking, and stabilization. Recruitment to the postsynaptic membrane means greater ...
Bryan Krause's user avatar
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2 votes

Storing bacteria in a dry, room temperature long-term storage whilst maintaining viability

Lyophilization, aka freeze-drying, is probably the go-to method of microbial preservation without the need for cold storage. It's how bacterial strains purchased from commercial culture collections ...
MikeyC's user avatar
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2 votes
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Who discovered that phage phiX174 has a single-stranded genome?

I think @MaximilianPress was close. Chargaff certainly did early work on DNA structure, but he was not the one to identify that the genome of φX174 was circular. As far as I can tell, the actual peer ...
bob1's user avatar
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2 votes

Do right-handed helices bind to right-handed helices, and vice versa?

My understanding is that protein and DNA helices show the handedness that they do due largely to the intrinsic chirality of their components. Note that in natural biomolecules L-amino acids and D-...
Maximilian Press's user avatar
2 votes

What is H-activation vs. O-activation in the context of cellular respiration?

The answer to this question is to be found in an extensive biography of Warburg published by The Royal Society of London in 1972, written by his former pupil and fellow Nobel laureate, Hans A. Krebs. ...
David's user avatar
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2 votes
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Do cells know or imagine how each part of the DNA influences body structure and function? How else would evolution happen in specific ways?

The short answer, is that there is no current knowledge of any coding or intelligence outside the DNA. The long answer (see chat) is that some scientists speculate on cellular intelligence and the ...
Nav's user avatar
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1 vote

Who discovered that phage phiX174 has a single-stranded genome?

Update please see @bob1's answer below. Original answer I suspect that this is the paper you are interested in but I can't find even an abstract of it due to the obscurity/loss of the journal. In a ...
Maximilian Press's user avatar
1 vote

Mesh formation in the wells of SDS PAGE. How to solve it?

This issue is driving me crazy too. Although I haven't identified the exact cause, here are the steps I've taken to minimize mesh formation: (1) Prepare your gel on the same day you plan to perform ...
oklu's user avatar
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1 vote

Storing bacteria in a dry, room temperature long-term storage whilst maintaining viability

The answer to this strongly depends on the species of bacterium you are working with. The only ones that I know of that are capable of withstanding any dehydration process are those that form spores. ...
bob1's user avatar
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1 vote
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Why doesn't treating neurons with a high sodium solution depolarize their membranes?

I would start with the Goldman equation, plug in some reasonable values and experiment with the results. Your reasoning I think comes from a common misconception that involves counting positive ...
Bryan Krause's user avatar
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1 vote

Can a person have different sex at cellular level?

Every organism(sexually reproducing) starts life from a single cell zygote formed by union of sperm and ovum. Since all cells are formed by mitotic divisions and differentiation of the zygote, the ...
Aurelius's user avatar
  • 197
1 vote

Does recombination occur in both chromatid of a chromosome with homologous chromosome? Or only 1 chromatid participate in crossing over?

I think like that , different alleles coding for different traits are present on different positions on two chromatids So both can participate in the recombination only when chromatids of torquoise ...
Vidushi Aggarwal's user avatar

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