Questions tagged [dna]

Deoxyribonucleic acid (DNA) is the carrier of genetic information, including for all known living organisms. The only known exceptions are RNA viruses.

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Why is the genetic code is like that?

I'm following an online course, the Secret of Life by MIT. It excels at teaching the who & what & how, but doesn't really tell me why. For example, the genetic code is like that all over ...
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When does DNA transcription occur? (or what triggers it)

To be specific, I'm not looking for answer such as "when dna polymerase bind to the promoter region of the dna". The question is rather, what triggers the process in the first place? Does ...
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Dealing with heterochromatin during DNA replication

Heterochromatin are present along the chromosome (uncoiled state). With the highly-condensed structure relative to euchromatin, RNA polymerase cannot get into the DNA base pairs in heterochromatin and ...
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DNA mutations in humans are generally bad, but why in viruses make their bodies stronger?

I want to know why this happens to viruses. can we apply that technique to the human body too
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Are there ribozymes that cut double strands

the header already says: Are there any ribozymes known that cut double strands? A kind of ribozyme equivalent to the Ribonuclease III. With cut, I mean that the backbone of both strands, forming the ...
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If aging is caused by “DNA Damage” why is the process of aging generally similar between people?

When I hear the phrase "DNA Damage" I imagine completely random changes in the DNA of a person's cells. If this is the case, then it seems like every person would age differently depending ...
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Why do microarrays require a priori knowledge of the genome?

Reading this paper they said this: Contemporary microarrays emerged in the wake of genome sequencing projects for one obvious reason: arrays require a priori knowledge of the query genome Why do you ...
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Why does DNA synthesis require nucleoside triphosphates? [closed]

Writing the DNA sequence is done with nuclosides that have three phosphates attached to them, and two of these phosphate are thrown away back into "phosphate pool" of cell. What are main ...
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88 views

When the sister chromatids are joined in the centromere, why is it stated that the number of chromosomes is 46 and not 72?

Before the DNA is replicated in a human somatic cell, the cell has 46 chromosomes. Also, after the sister chromatids are separated during Anaphase, the chromosome number in the cell doubles to 72, so ...
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What's the difference (functionally speaking) between yeast centromeric plasmids and artificial chromosomes?

Historically, yeast artificial chromosomes (YACs) have been used for genome sequencing projects in the late 1990's. Nowadays, most researchers seem to use centromeric plasmids for expressing ...
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What is the structure of heterochromatin?

A short article about euchromatin and heterochromatin mentions that the structure of heterochromatin usually depicted in images "has never been visualized in vivo, and its existence is ...
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104 views

Get “DNA” of one parent based on its children [closed]

I'm no biology expert so bear with me, but I've been given a task to estimate alleles of an animal based on the animal's children and the children's other parents. I've looked up Mendel's laws but I'm ...
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Are archaeological DNA samples (bone fragment) stabilized and isolated the same ways as living saliva samples?

I've been studying how saliva DNA samples are suspended in a stabilization fluid then isolated using magnetic beads. Are old archaeological DNA samples of deteriorating bones put through this same ...
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Exact average molecular weight of a dsDNA basepair

I am trying to calculate the exact weight of a given dsDNA. On the Internet and the literature, different values for the av. molecular weight of one basepair are given : 660 g/mol (probably wrong), ...
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51 views

Parameters that determines the thermal stability of DNA

Why a DNA with a high GC content more stable than one with a less GC content? Is it because of the three hydrogen bonds in GC base pair which is one more than a AT base pair or is it because of the ...
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52 views

Did Mendel believe that proteins are hereditary substances?

Scientists first thought that proteins, which are found in chromosomes along with DNA, would turn out to be the sought-after genetic material. Proteins were known to have diverse amino acid sequences, ...
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What data would Meselson and Stahl have expected if DNA replication was dispersive rather than semiconservative? [closed]

What data would Meselson and Stahl have expected if DNA replication was conservative rather than semiconservative? Answer: In the first generation, there would be two bands, one of light density and ...
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What is the mechanism through which fractals arise in plants and animals?

Many biological organisms -- such as trees, broccoli, and the blood vessels in animals -- can be approximately described using fractals. What is the reason behind such fractals? Specifically, do we ...
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DNA extraction from parasitic worm

I have a part of a parasitic worm frozen at -20°C. Do you think that DNA extraction using DNeasy kit without any pre-treatment is sufficient for DNA extraction? Or would you recommend bead beating / ...
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Is there a term for the opposite of intergenic?

I am looking for a term that describes DNA regions that overlap genes, i.e., non-intergenic DNA regions. For example, say I am writing a paper about DNA-binding sites (i.e., DNA sequences that ...
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What are the advantages of long read sequencing for cancer oncogenomic research?

Currently I am using whole genome nanopore sequencing, Illumina short read and 10x linked read to study oncogenesis mechanisms of certain types of rare cancer. I am wondering about the advantages of ...
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Poly-G tails in NovaSeq Paired-end sequencing from museum samples

I'm currently working with DNA samples originating from museum specimens, this means they have been stored in formaldehyde for the last 50-100 years. The DNA I'm analysing has been sequenced by ...
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60 views

Purpose of EF1 alpha promoter

Context: I have seen promoters used to have gene therapy viruses target specific cells, so I am referring to that apparent function of theirs. As an example I have seen GFAP promoters used for ...
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67 views

Why are there 10 base pair steps, not 16?

In a biochemistry course I'm taking, the lecturer emphasised that there are 10 possible base pair steps; I've included a screenshot of a slide stating this. This confuses me, because I cannot work out ...
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Can Taq polymerase be stored with PCR primers?

I don't think it's possible for TAQ to be stored with the primers, but I'm not sure. This storage wouldn't be long-term (a few days, or a week at most). Thoughts?
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How do we regulate the production of proteins when designing plasmids?

I think it should be no surprise that I, as many others, am interested in the new COVID-19 vaccines being developed. In my region of the world there are two mayor candidates. One is mRNA based and one ...
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57 views

How to identify the subspecies/breed of a bee

I have been a beekeeper for a number of years and originally obtained my first colonies from a guy in my neighbourhood. However, when I sell bees to someone else, they typically ask what species of ...
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102 views

How long does foreign DNA stay intact in human blood?

How aggressively is foreign DNA in blood targeted and degraded by the human body? I am asking because we have a metagenomics project where we want to detect parasite DNA in the human blood. The ...
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How does the order of the pairs of cross-links in DNA determine the arrangement of the amino acids?

Quoting Richard Feynman from Chapter 3 of his book Six Easy Pieces, when he talks about DNA: Attached to each sugar along the line, and linking the two chains together, are certain parts of cross-...
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metaphors for explaining the role of DNA in the cell [closed]

Various metaphors are used to explain the central role of DNA in a cell to laypersons. These include blueprint, recipe, catalogue, instruction manual etc. I even heard someone describing DNA as a '...
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Some related questions about DNA differences in a single organism

If you took a DNA sample from someone's brain and that same persons liver at more or less the same time, would that DNA - all else being equal (e.g. no mutations from radiation) - be exactly the same? ...
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Why is a solution of cesium chloride used in Meselson & Stahl's DNA replication experiment?

Centrifugation involves separating particles of different sizes, masses, density and etc. In the experiment, the DNA macromolecules are suspended in a solution of cesium chloride gradient and then ...
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44 views

Self-replication in the genome in the seed

Is the genome in the seeds of the plant turned off? That is, does the DNA in the seed not self-replicate? My second question is, what are the cells feeding on inside the seed before it is planted?
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Can Euchromatin convert into Heterochromatin?

I know that Heterochromatin can convert into Euchromatin but is the reverse possible? If yes, then How?
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What is the definition of gene, genotype and phenotype, pre and post DNA?

i know that the definition of gene is a unit of heredity, also a sequence of nucleotides in DNA that gets copied to RNA and then proteins. Genotype is the genetic composition of an individual ...
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How does permanently modifying human DNA work? And how does it impact procreation?

So I read an article about a metabolic disease being treated with gene therapy, where they inserted corrective dna into the patient. https://www.independent.co.uk/news/science/dna-permanent-change-...
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Would an enrichment of pyrimidine runs of two of more nucleotides be an early indicator of DNA to be damaged?

I am analysing two categories of protein coding genes comparing their relative characteristics. What I am observing is that one of these, in comparison to the other, is enriched in pyrimidine runs (...
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66 views

Is synthesizing DNA in-house feasible?

I've been reading up about DNA writing, and it seems there are machines available around the five-figure US dollar mark for DNA synthesis, and I'm considering picking one up for my lab. We normally ...
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Extracting DNA from a kiwi

I have two questions regarding this experiment. Online instructions say to use 5g washing up liquid, 2g salt and 100ml tap water mixed together with a mashed up kiwi. Do I use a full kiwi ? ...
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Can we apply NGS (next generation sequencing) on DNA extracted from formalin fixed paraffin embedded tissues (FFPE)?

I'm working on the microbiome and I can only use tissues which are fixed with formalin and embedded in paraffin. Is it possible to apply NGS (next generation sequencing) on FFPE (formalin fixed ...
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What does Δcys mean after a gene name?

I am reading a paper and I have come across the following statement: "Plasmids encoding full-length NCAM140 and NCAM140Δcys, intracellular domain of NCAM140, and the NCAM140ID729–750 fragment ...
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Meaning of 5’–3’ in relation to ORFs

I was reading a paper in the journal Molecular Basis of Disease, which stated: The ORFs are arranged as replicase, and protease and major S, E, M, and N proteins which follows a typical 5’—3’ order ...
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Which was the first DNA-based genome to be sequenced?

The Wikipedia article on phi X 174 states that: The phi X 174 (or φX174) bacteriophage is a single-stranded DNA (ssDNA) virus that infects Escherichia coli, and the first DNA-based genome to be ...
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Why is my DNA band bulging?

This is the only image my the TA was able to get for us. And, we're using it for our lab report. The image isn't even ours. It's another group's image that we're sharing. But I don't understand why in ...
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Do we come to know which allele is dominant by seeing family genration tree only?

I know that a Gene has Alleles (variation) and one is Dominant over Other i.e the Other Recessive. Then I got a Thought that How can we tell whether an Allele is Dominant or Recessive...... and I came ...
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How does the position of hydroxyl group in a nucleotide monomer affect the dehydration synthesis of nucleotides?

In dehydration synthesis of nucleotides, the hydrogen atom from the 3' carbon on the deoxyribose sugar of one nucleotide reacts with the hydroxyl group on the phosphate group of another nucleotide to ...
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71 views

Sequence of DNA

While giving an amateur reading to DNA. I was stuck within the first few lines: Refined resolution of the structure of DNA, based on X-ray crystallography of short synthetic pieces of DNA, has shown ...
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Why can DNA tests with mixed DNA of several people not be used to detect a criminal in a database?

Scenario: Two males attack another pair of two males with a weapon. The attackers are fought off and the weapon remains. Why does the police require DNA samples of the two who have been attacked to be ...
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Empirical Measurements of Barr Body Ratio

'Both X-chromosomes in a female have an equal chance of becomes a Barr body in each cell.' Every source I can find on Barr bodies claims this and I can think of no reason for why it may be wrong. What ...
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a biochemical pathway for evaluating the effect of 3' to 5' exonuclease on the proofreading activity of DNA synthesis

Can the following oversimplified biochemical pathway for DNA synthesis serve as a model for evaluating the degree of the effect that the 3' to 5' exonuclease affinity for mismatched base pairs can ...

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