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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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Does DNA have the equivalent of IF-statements, WHILE loops, or function calls? How about GOTO?

Does DNA have anything like IF-statements, GOTO-jumps, or WHILE loops? In software development, these constructs have the following functions: IF-statements: An IF statement executes the code in a ...
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3answers
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Why is thymine rather than uracil used in DNA?

What is the advantage gained by the substitution of thymine for uracil in DNA? I have read previously that it is due to thymine being "better protected" and therefore more suited to the storage role ...
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4answers
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Does the string “…CATCAT…” appear in the DNA of Felis catus?

In Hofstadter's Gödel, Escher, Bach: An Eternal Golden Braid (GEB), the following claim appears: ...in the species Felis catus, deep probing has revealed that it is indeed possible to read the ...
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Life without DNA?

I'm by no means an expert in the field, merely a curious visitor, but I've been thinking about this and Google isn't of much help. Do we know of any lifeforms that don't have the conventional double-...
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What exactly are computers used for in DNA sequencing?

I've thoroughly read the Wikipedia article on DNA sequencing and can't get one thing. There's some hardcore chemistry involved in the process that somehow splits the DNA and then isolates its parts. ...
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2answers
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How do cockroaches resist the effects of ionizing radiation?

Cockroaches are very hardy insects. It is known that, among other things, they are able to withstand bursts of ionizing radiation that would kill a human being. The explanations of this observed ...
44
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1answer
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What am I looking at in Franklin's Photo 51 of DNA?

Here's Rosalind Franklin's famous Photo 51, the X-ray diffraction image of DNA from which Watson and Crick deduced its structure: My understanding is that it depicts a short segment of DNA shown from ...
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Why do eukaryotic organisms have introns in their DNA?

We touched on introns and exons in my bio class, but unfortunately we didn't really talk about why Eukaryotes have introns. It would seem they would have to have some purpose since prokaryotes do not ...
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What does it mean to “write an image and GIF into the DNA of bacteria”?

BBC News recently published an article saying that: An image and short film has been encoded in DNA, using the units of inheritance as a medium for storing information ... The team sequenced the ...
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2answers
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What is the advantage of circular DNA in bacteria?

From what I understand, bacteria have circular DNA. What advantages does it have over linear strands like for eukaryotes? Do there exist bacteria with more than one ring of DNA?
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Is telomere length a reliable measure of health/lifespan?

Several companies are commercializing tests for telomere length such as this one here. I understand the basic mechanism for why telomeres shorten during DNA replication, but how good is the evidence ...
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Why is DNA replication performed in the 5' to 3' direction?

DNA replication goes in the 5' to 3' direction because DNA polymerase acts on the 3'-OH of the existing strand for adding free nucleotides. Is there any biochemical reason why all organisms evolved to ...
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Which organism has the smallest genome length?

Which animal/plant/anything has smallest length genome?
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6answers
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Why are there exactly four nucleobases in DNA?

Does someone know why DNA is composed of four nucleobases? In particular, is there an explanation for the number? Why four and not two, or eight?
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Do apes and humans share 99% of DNA or 99% of genes? What is the difference?

I made an answer on the Scifi.SE that can be read here. It is about how the characters in the story Jurassic Park might have gotten DNA for all the species shown. In my answer, I said this: Apes ...
21
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3answers
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Does our DNA change during our lives?

As far as I know, DNA is the construction protocol of all organisms on Earth. Does it change when influenced by time and environment (physical laws)? As parents with schizophrenia are more likely to ...
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4answers
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Why deoxyribose for DNA and ribose for RNA?

Why is DNA made out of deoxyribose and RNA made of ribose? Why can't they both use ribose or deoxyribose? I think that the deoxyribose gives an advantage in storing genes, the job of DNA and ribose is ...
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1answer
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Are human chromosomes connected or separate molecules?

Do the 46 human chromosomes form a single unbroken DNA helix? Or is it rather that a human's genome consists of 46 disconnected helices? If it is the former, does the common numbering scheme for ...
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2answers
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Is there an advantage to linear chromosomes?

The DNA copying enzymes have a hard time working to the end of a chromosome. For circular chromosomes this is not a problem, since there is not a sharp 'end'. However, for a linear chromosome, without ...
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1answer
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How old is the oldest intact DNA?

DNA fragments are known from bone fragments from the Mesozoic, but these don't count. I'm guessing the oldest DNA is recovered from permafrost, but how old exactly?
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Could Junk DNA be used as a Turing Machine by nature?

In what ways has DNA been studied to see if there a "programmable" aspect to it? Has nature produced anything resembling a Turing machine within the cell, perhaps using the "junk DNA" as its code? I ...
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2answers
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What does 5' and 3' mean in DNA and RNA strands?

What are 5' and 3' in DNA and RNA strands? Please clarify with some images and please use simple English.
18
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1answer
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What is the prehistory of amino acids in cells?

As a followup to Why 20 amino acids instead of 64? and What is the smallest number of amino acids required for life?, I am trying to understand the prehistory of amino acids in cells. All living ...
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Are there examples of cells with more than one nucleus?

I've always wondered why cells have only one nucleus, as having multiple would seemingly prevent mutation. Are there examples of organisms with multiple nucleuses? If not, is there a reason?
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why is DNA antiparallel? Can it be parallel?

My biology textbook mentions that DNA is antiparallel and it got me wondering... Can DNA be parallel? What would happen if it was parallel? could DNA still replicate right?
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3answers
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Is the size of the genome across species roughly the same?

Chromosome number differs across species. Is the amount of DNA comparable between organisms, just being split into smaller chunks in those species with more chromosomes, or do species have different ...
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8answers
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Is there a biological mechanism for evolution encoded into our DNA?

Throughout high school, I remember learning about Darwin's theory of evolution as if it were near-fact. But something always seemed wrong about the ideas presented. Survival of the fittest Random ...
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4answers
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Evolutionarily speaking, why do humans have 46 chromosomes

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Monkeys, chimpanzees, and Apes have 24 pairs (twenty-four pairs), for a total of 48. What caused humans to have 46? ...
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5answers
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Why did high A+T content create problems for the Plasmodium falciparum genome project?

The main paper for the Plasmodium palciparum genome project (Gardner et al., 2002) repeatedly mentioned that the unusually high A+T content (~80%) of the genome caused problems. For example they imply ...
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4answers
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What implications has the missing 2'-OH on the capability of DNA to form 3D structures?

The chemical difference between RNA and DNA is the missing 2'-hydroxyl group in the nucleotides that build DNA. The major effect of that change that I know of is the higher stability of DNA compared ...
15
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3answers
937 views

Are there differences in DNA between humans of today and humans from 2000 years ago?

Are there any significant differences in our genome compared to the genes of our ancestors from 1000-2000 years ago? And if there are significant differences, do they result in significant ...
15
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2answers
372 views

Can methylation from DNA get copied to RNA during transcription?

Methylation on gene-body and 3'UTRs if copied to mRNA can potentially regulate post-transcription modifications or expression regulation. But I'm not sure if they are maintained after transcription or ...
15
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2answers
558 views

What is the contribution of viruses to the evolution of mankind?

I'm interested in horizontal gene transfer in bacteria, viruses, and organisms such as Bdelloid Rotifers. I've just read in Carl Zimmer's 'A Planet of Viruses' the following passage: As a host cell ...
15
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1answer
771 views

Can DNA act as a translation substrate?

I get conflicting answers. One would think if it was true, it would be rather seminal and widely known. There are papers from Khorana[1], Holland[2], and Bretscher[3] (late 60s) that suggest that it ...
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3answers
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How do we know Neanderthals DNA?

According to this article, a small amount of Neanderthal DNA was introduced into the modern human gene pool. How do biologists even know what the Neanderthals' DNA look like? The article doesn't ...
14
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2answers
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Linear and Circular DNA

So school has taught us that eukaryotes have DNA that is linear and inside of a membrane - called the nucleus. And that prokaryotes have circular DNA that is free floating inside of the cell. We ...
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2answers
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The Uniqueness of DNA Paradox

How can everyone have unique iris and fingerprints? After a certain amount of human beings have lived on earth, wouldn't it be possible to exhaust all possible combinations? The same principle ...
14
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2answers
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Is a DNA molecule a single strand of polynucleotide or two of them linked together?

I'm so embarrassed to ask such a question here, but our molecular biology teacher told us that a double helix of DNA was composed of two DNA molecules linked together by hydrogen bonds. The thing is, ...
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4answers
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Computer Virus that infects DNA?

I have watched a talk by Mikko Hypponen (CEO of the security company F-Secure) called Silicon Plague. There, roughly at minute 51 of the talk, he mentions a computer code that is supposed to be able ...
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2answers
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Do transcription factors bind to both strands of DNA?

Do transcription factors (or generally proteins) bind to only single strand of DNA or both strands? Since it can have non covalent bonds to both strands in theory. I would like to know the mechanism. ...
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2answers
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Why is uracil, rather than thymine, used in RNA?

This question was posed on SE Biology some time ago, but all the answers, including the accepted one, answered a different question instead: “Why is thymine, rather than uracil, used in DNA?”. I ...
14
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1answer
7k views

Solubility of DNA in water

This would seem to be an easy to answer question, but I was unable to find an answer (in g/L) for generic double-stranded DNA or plasmid neither on Google nor on BioNumbers. I would expect the ...
14
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1answer
8k views

How to DIY preserve pet DNA today so that it can be used in 20 years

I know that there are companies that offer a kit+storage of your pet DNA for around $2k. My question is if there is any other option for doing this yourself with a thought in mind that in 20+ years ...
14
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1answer
3k views

Does every mitochondrion in a cell contain the same DNA?

I know that mitochondria of eukaryotes have their own DNA, more similar to that of bacteria than to the rest of the cell's DNA. I also know that a cell can have plenty of mitochondria, and I ...
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4answers
2k views

“Same” DNA vs genes

It is often cited that humans share 99% (or 98%) of their DNA with chimpanzees. On the other hand it is stated that siblings share only half of their genes. What (if any) is the difference between ...
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3answers
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Does a man contain all the genes needed to make a woman?

This question is brought on by a Sci Fi novel I am thinking about writing. The plot device involves a colonist in charge of building a population on a new planet who loses his supply of embryos and so ...
13
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1answer
88k views

Why do we add salt when precipitating DNA?

All the DNA extraction protocols I have seen involve adding salts to the extraction buffer. What is the purpose of the salts? What happens if they aren't included?
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2answers
875 views

Do mitochondria simply automatically convert glucose to ATP?

I wonder whether there is any intelligent decision-making in mitochondria in the timing of their operation. Do they simply begin ATP production as soon as the correct reactants are present? Or, ...
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2answers
2k views

Why is thymine not incorporated into mRNA?

I am aware that in transcription uracil bonds to adenine and not thymine. But what is it that actually prevents thymine from bonding to adenine in transcription, that is not present in replication?
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1answer
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Abiogenesis: Beyond the research journals as a lead in to discussions on evolution

I just came across this abstract: Aminoacyl-tRNA synthetases (aaRSs) are responsible for creating the pool of correctly charged aminoacyl-tRNAs that are necessary for the translation of genetic ...