Questions tagged [dna-replication]

The biosynthetic process by which copies of a DNA molecule are made.

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2 answers
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Can DNA replicate without polymerase?

Would it be possible for short DNA molecules to replicate, for example, if it's heated to the point where the strands separate (as far as I know, that's what happens in PCR?) and freely floating bases ...
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Why are RNA nucleotides added first, only to be replaced by DNA nucleotides during DNA replication?

I am not asking why RNA primer needs to be added, but rather why RNA nucleotides are added as a primer by Primase and replaced by DNA polymerase I? It seems very inefficient to first insert RNA ...
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Why are telomeres needed to allow DNA replication at the ends of linear chromosomes?

I’m reading Molecular Biology of the Cell by Alberts et. Al and at one point the authors mention the following: We saw earlier that synthesis of the lagging strand at a replication fork must occur ...
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The numbers of chromosomes during Meiosis [duplicate]

There is something about the numbers of chromosomes that doesn't make sense to me: Let's take this illustration: So a gamete has 23 chromosomes, which are haploid (have only one chromatid), is that ...
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Why do eubacterial DNA Ligases use NAD whereas eukaryotic and archaeal DNA Ligases use ATP?

DNA ligases in eukaryotes are ATP-dependent (as is the enzyme from bacteriophage T4) but in Escherichia coli the DNA ligase is NAD+-dependent. I cannot understand the reason for this. An extensive ...
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Time required for DNA replication in E. coli

In a particular strain of E. coli, it was observed that DNA polymerase could add nucleotides to a growing chain of DNA at the rate of 600 per second. If the genome of this organism is 1.1mm long ...
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What is, (and what isn't) "kinetic replication" as it applies to molecules and to living organisms?

CNN's World's first living robots can now reproduce, scientists say describes "xenobots"; clusters of stem cells that move around and by this motion occasionally push enough free stem cells ...
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Does DNA ligase have any role to play in replication on leading strand?

Actually I developed this doubt while solving some questions(they are poorly framed I suspect). According to my notes and my institute modules, 1 RNA primer is required on the leading strand as well ...
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Why is exonuclease action an important proofreading mechanism?

My copy of the Molecular Biology of the Cell (the 5th edition, so not entirely up to date) seems to claim that exonuclease action is an important part of DNA proofreading, and that dysfunction in ...
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Can we cure cancer with CRISPR dead Cas?

Here's a silly idea I had this morning: Sequence a bunch of normal patient cells. Sequence a bunch of tumor cells from a biopsy. Find a DNA sequence that we're reasonably certain exists in the cancer ...
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1 answer
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Why don't we use hybridization instead of PCR? [closed]

So, I would like to ask, why don't we use just DNA hybridization instead of PCR primer amplification to diagnise some illness? I know, when you have a really small amount of DNA from virus or cell you ...
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Do the genes for external viral epitopes mutate faster than for viral machinery (e.g. Proteases)?

To fight SARS-COV-2 we use vaccines which train our immune system against viral epitopes like the external S(pike) protein. Since these structures change a lot, would it not have been a better idea to ...
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Thermodynamically, how did the first cell arise?

Living cells are biochemical systems that constantly perform chemical reactions. One of the important consequences of these chemical reactions is the capacity of a living cell to replicate itself. The ...
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Which method of gene amplification for toehold switches?

My team and I are from a high school and are planning to carry out some research investigating some toehold switch riboregulators which we have designed in silico. However, we have little experience ...
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Can a strand not be synthesised in 5' -> 3' direction?

I've been solving some biology questions, and according to one of them ( I have the responses too) the following phrase is false: "Both strands are always synthesised in the 5' to 3' direction.&...
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Why is DNA replication not 100% accurate

I've been reading about DNA mismatch repair (MMR) and how this process improves DNA fidelity. However, I was wondering, what is stopping MMR from correcting all mistakes in the daughter DNA with 100% ...
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Does gene orientation relative to origin of replication matter on small plasmids?

The recent question about forward vs. reverse strand got me thinking about directionality conventions in synthetic biology. As noted in the answer to that question, if we consider only DNA in ...
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SARS-COV-2 replication speed

What is the speed of replication of SC2? Any information, including in vitro data would be appreciated. I would be interested to know the length of SC2 eclipse period, latent period and something like ...
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Nomenclature of substrates for DNA synthesis

I have read in my school textbooks that both deoxyribonucleoside triphosphate and deoxynucleotide triphosphate are used in DNA Replication as substrates. However, it is unclear to me whether the terms ...
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Is there a DNA sequence that is true for all primates?

There are a total of 324 million known variants from sequenced human genomes. https://en.m.wikipedia.org/wiki/Human_genetic_variation Is there an DNA sequence that is true for all primates? Is this ...
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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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Why is DNA replication so much faster in prokaryotes than eukaryotes?

There are many statements to be found on the internet of the sort: “DNA replication occurs at elongation rates of about 500 nucleotides per second in bacteria and about 50 nucleotides per second in ...
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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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Is there something amounting to "check sums" in genetic code?

Humans use checksums for many different applications in informational processes. Genetic code is used as a "program" to synthesize proteins, so it could (I'm a layman when it comes to ...
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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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Polymerase Chain Reaction Specifics

While going over PCR in my biology lecture this week I have come across a few questions I have about this process. First, since PCR focuses on trying to replicate a specific targeted DNA sequence many ...
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Does DNA being circular or linear directly affect the speed of DNA replication?

Let's say we have two DNA molecules of equal length, one belonging to a prokaryote and the other to an eukaryote. It's known that replication of the eukaryotic DNA is faster in this case. One clear ...
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Is the leading strand consistent in the same chromosome with multiple replication forks?

If a chromosome has multiple origins or replication, do those origins necessarily pick the same DNA strand as leading and the same one as lagging, or can they be of opposite orientations, sending ...
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Universal clock for humans contained in the telomeric sequences?

I don't know if this would make sense, but imagine that we could only suffer from natural aging (not diseases whatsoever involved). Is there an estimate of what is our natural maximum lifespan that a ...
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Why does the structure of RNA change? [closed]

RNA only has one strand, but like DNA, is made up of nucleotides. RNA strands are shorter than DNA strands. RNA sometimes forms a secondary double helix structure, but only intermittently. Why does ...
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Can mutation take place in G1 and G2 phases during the cell cycle?

We know that the DNA replicates during the S phase in Interphase. There it might undergo a number of mutations. We also know that the forward half strands are more susceptible to undergoing a mutation ...
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Replicate DNA so its visable to the naked eye

So my question has a few sub sections after the main title question. Firstly, is it possible to replicate a pure sample of an individuals DNA to an amount that is visible to the naked eye? If ...
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Eukaryotic DNA polymerase in Leading and Lagging Strand

Different books say a different specifications on which eukaryotic DNA polymerase work in leading strand and which DNA polymerase work in lagging strand. TL,DR: Which one is reality? and if there ...
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How does DNA shape a living organism? [closed]

I'm haven't studied biology so excuse me if I'm getting something wrong. I'm trying to understand how the DNA from a sperm and egg cause the egg too multiply and form a perticular shape (shape of a ...
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How can DNA replication result in hair pin structures?

My professor said that one of the reasons SSB proteins are so important was to prevent the formation of hair pin structures, I can't see how or why DNA would form hairpin structures and there's not ...
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Is there any current knowledge of how DNA polymerase is "motivated" to perform error corrections during transcription?

I was trying to understand the process of how polymerase performs error corrections on DNA. Every paper on this topic mentions what happens during the process, but there's no mention of how it happens....
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Why does inbreeding cause genetic defects, but cell division in one's own body does not?

I was watching a DNA transcription video when I realized that cells basically create copies of DNA all the time in our body. There may be a few mutations/errors, but it works out fine. However, when ...
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Why is Homologous Recombination (HR) more frequent at long sequence repeats?

I'm studying plasmids in bacteria (E. coli), and trying to understand the well-cited phenomenon that recombination frequency increases with longer repetitive sequences. I think this also applies to ...
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How exactly does DNA polymerase III detect a mismatched base?

How exactly does DNA polymerase III detect a mismatched base? I know how it removes it, via exonuclease activity, but how does it 'detect' it molecularly in the first place?
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In DNA replication, are there phosphodiester bonds in the primer ? between the RNA nucleotides before being replaced

When hydrogen bonds happen between the RNA nucleotide bases and the DNA bases , do phosphodiester bonds form between the RNA nucleotides in the primer ? No source I read is clear about this, are ...
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What's the transposon difference between chimps and humans?

I was reading that humans and chimps share 98-99% of the same DNA sequence but I also read humans and chimps only share around 20% of the same proteins. Also, 45% of the human genome is transposable ...
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Is variation a result of Evolution?

We know that the DNA copying mechanism that replicates DNA during cellular division is not 100% accurate and the resultant errors are the source of variation in the members of a population. At the ...
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In Griffith's experiment, if both S and R strains are added, can the R strain be isolated from the blood of the mice?

In Griffith's experiment on transformation, when both the S strain and the R strain were injected into the blood of the mice, could the R strain be isolated from the blood of the dead mice? I think it'...
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Did the first cell self-replicate or was it multiple first cells? [closed]

We're almost sure by now that the first cell was born in a some kind of underwater vents environment which harvested all the necessary conditions for it to exist. However, did the first cell self-...
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DNA replication - 2 new strands or original (parent) and child?

this is my first time here, so go easy on me! I've been trying to find out more about the actual process of DNA replication. Specifically, I am wondering if, when the DNA replicates during cellular ...
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DNA replication in $ E.coli $

$ E.coli $ has circular DNA which I guess implies one strand forms the outer circle and the other the inner one. So, is there a way to know if the replicated DNA forms the outer or inner circle? In ...
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How is it possible for phosphate to form two ester bonds in DNA replication?

I understand that in phosphodiester bond formation, two hydroxl groups on the phosphate molecule bind to the 3' and 5' OH groups on two independent pentose sugars. This is a condensation reaction, so ...
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How does bonding between non-complementary bases occur?

My teacher told me that when DNA polymerase makes an error (roughly every 10 million nucleotides?) that if, for example, it matches an A with a G that the error remains and is the main cause of point ...
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What are the issues with excessive tandem repeats in replication?

Why is it that tandem repeats like CAGCAGCAG cause primer-template misalignment and diseases like Huntingtons disease? By my understanding, too many such repeats can cause strands to form hairpins and ...
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DNA replication - how many times and when does it occur?

I’m currently learning about DNA replication in both prokaryotic and eukaryotic cells. And my lecturer has mentioned that replication is a once in a lifetime activity. And I’m not sure what this is ...