Questions tagged [dna-replication]

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

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1answer
77 views

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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1answer
76 views

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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1answer
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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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54 views

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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1answer
103 views

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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1answer
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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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1answer
154 views

Does direction 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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1answer
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Difference in length of Okazaki fragments

The length of Okazaki fragments in the lagging strand is about 100-200 nucleotides in eukaryotes and about 1000-2000 nucleotides in prokaryotes. What (molecular mechanism, enzyme type ) determines ...
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1answer
103 views

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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2answers
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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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0answers
161 views

Can a dividing cell that skipped DNA replication become cancerous?

Let's assume that a cell fails to replicate its DNA during the S Phase of the cell cycle. Let's also assume that the appropriate CDKs are inactive (perhaps due to mutation or lack of cyclin proteins ...
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30 views

Are there any "in vivo" DNA replication fidelity assays?

I haven't been able to find a way to assess the fidelity of DNA replication in vivo as opposed to in vitro. I was wondering, would it be possible to find this by sequencing the DNA of individual cells ...
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1answer
100 views

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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1answer
112 views

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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2answers
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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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1answer
144 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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1answer
488 views

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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1answer
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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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1answer
2k views

After the primer is removed from the leading strand, how does DNA polymerase I add dNTPs without a 3'-OH?

I have a question about replication in prokaryotes. I learned in school that: DNA polymerase needs 3'-OH to add a dNTP. The chromosomes of prokaryotes are usually circular. The primer in the leading ...
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0answers
25 views

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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2answers
315 views

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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2answers
105 views

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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1answer
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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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1answer
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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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1answer
38 views

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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1answer
106 views

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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1answer
119 views

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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2answers
41 views

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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2answers
92 views

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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67 views

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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1answer
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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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3answers
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How does high-fidelity of DNA replication depend on the formation of hydrogen bonds?

Replication has an error rate of less than 1 in 100 million. DNA polymerase forms H-bond with the H-bond acceptor atoms in the minor groove. <-- enhance fidelity here? Binding of the triphosphate ...
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1answer
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Do telomeres appear at just one end of the chromosome?

I have just studied DNA Replication for my Biology Class and I have this question that leaves me stuck, though I have tried to figure it out myself. During telomere replication, I am aware Telomerase ...
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1answer
216 views

Why does deamination in the lagging strand lead to an increase in the relative number of guanine and thymine to cytosine and adenine?

My question arose from this article on Wikipedia on the GC-skew in bacterial genomes: https://en.wikipedia.org/wiki/GC_skew As far as I understood, the lagging strand (the template strand), during ...
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4answers
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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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Why replication collapse but not stall leads to DNA break?

I have been looking into the concept of replication dynamics and was wondering why collapsing but not stalling leads to a DNA break.
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1answer
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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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2answers
1k views

What is the name of the smallest self-replicating thing?

Some time last year, I found an article on Wikipedia about the smallest something to be able to reproduce. I don't remember exactly what it was, but I am fairly certain that after the initial ...
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1answer
199 views

How are single-stranded binding proteins removed from the lagging strand during DNA replication?

The lagging strand, downstream of the Okazaki fragment, is covered in single-stranded binding proteins (SSBPs) during DNA replication. What is the mechanism which ensures that SSBPs are removed from ...
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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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1answer
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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 ...
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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 ...