Questions tagged [dna-replication]

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

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59 views

Error frequency of DNA replication without proof reading activity of DNA polymerase?

Different domains of DNA polymerase contain different activity, like 5'->3' polymerisation and 3'->5' proof reading ...
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Molecular animations of, say, protein synthesis, are simplified, but how exactly?

In several animations of biological processes (eg protein synthesis (go to frame 1.20mins), DNA replication, etc), molecules such as amino acids are shown heading straight to the replicating protein ...
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DNA replication precision

This will sound as a super stupid question, but I just read in the Molecular biology of the gene book (7th edition, Watson, Baker, Bell and al.) that one mistake occurs in 10 million nucleotides added ...
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201 views

Why a cell contains all DNA when it only needs a few genes?

Is that what they called junk? Why does a simple cell have the DNA code for everything else when it just needs a few codes to function? Wouldn't that be a wasteful?
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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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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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225 views

How is the effect of proof-reading on error frequency during DNA replication determined?

An article in Nature Scitable on DNA Replication and the causes of Mutation states that: When an incorrect nucleotide is added to the growing strand, replication is stalled by the fact that the ...
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DNA synthesis in nucleus

I read somewhere that according to a research, I don't remember what the date was, that our cells stop synthesising DNA around noon and restart it around the sunset. The research told that it was ...
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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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In PCR what is the chemical makeup of the primer? DNA or RNA? [closed]

I'm thinking the answer is RNA. Is that right?
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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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Don't understand how multiple replication bubbles work

I'm not exactly sure how multiple replication bubbles work, assuming were working with a linear, eukaryotic chromosome. This is a diagram for reference: It appears that the DNA is being synthesized "...
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Unsure about definition of "n" and "C" values in mitosis

I am preparing for a Biology exam and I'm reviewing the "n" and "C" notation used in mitosis. My professor said that when the cell replicates its DNA in S phase of mitosis, we get twice the "amount" (...
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1answer
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Why are stem cell therapies more preferred (theoretically) over current measures?

i understand that when stem cells are used to treat injuries using induced pluripotent stem cells (IPS), they can prevent the risk of having any tissue rejection and thus, there isn't a need for use ...
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what kind of bonds join the okazaki fragments

During DNA replication, the synthesized okazaki fragments adjacent to each other are joined up directly by DNA ligase-catalyzed phosphodiester bond formation. Can someone point out to me which part of ...
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What is a DNA clamp exactly?

I used to think that a DNA clamp is a protein. But today I noticed it doesn't appear in this picture. Then I went to it's Wikipedia page, where it was written: A DNA clamp, also known as a sliding ...
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Stem Cell Replication

Reading from the internet, I've come across quotes that said stem cells have the potential to replicate indefinitely. However, there are other sources that say cells that are specialised will have ...
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How is a portion of DNA selected and unwound from nucleosome?

If I understand this correctly during interphase most of the DNA strand is tightly wound around histones in the form of nucleosomes, to conserve space in the nucleus. Yet RNA polymerase in order to ...
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328 views

Does crossover happen between chromosomes from grandparents?

Rephrasing question: does crossover happen after sperm and egg meet each other, but before formed fetus starts to grow? As I understand sperm and egg of human are haploid cells. That means this cells ...
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Replication cohorts in microbial GWAS

Replication in an independent cohort is of course the gold standard in GWAS studies, and many high profile journals will now (quite rightly) not accept finding indicating a phenotype genotype ...
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4k views

Is water released when a phosphodiester bond is made between two nucleotides during DNA replication?

I know that when two sugar molecules (like glucose) connect to each other, H2O is released because of the -OH and -H groups in both of the molecules. I want to know if the same thing happens when two ...
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1answer
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Are bacterial RNA polymerases distributed evenly throughout the cell or localized?

Bacterial cells aren't internally compartmentalized with membranes (like eukaryotes). This naturally leads to an image of a homogeneous interior, but bacterial cytoplasm isn't homogeneous. Case in ...
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Is DNA replication a serial or parallel process?

This video entertainingly supplements this 3d animation of DNA strand replication. Does this process happen serially from the beginning to the end of a DNA strand (like having to unzip a six foot long ...
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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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When does the kinetochore form?

According to Wikipedia, the outer plate... is assembled in the surface of the chromosomes when the nuclear envelope breaks down. However is makes not mention of when the inner portion of the ...
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Is there any technique can quickly expand one set of cell chromosomes?

Assume a cell type is very scarce while isolated out and hard to expand in vitro, and I wanna have more of its chromosomes, is there any technique , in vivo or in vitro or ex vitro, any would count, ...
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When does histone synthesis occur in relation to DNA replication?

Do histones have to be synthesized before DNA is replicated to allow the DNA to coil around histones?
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Can translocation occur within a gene?

I know genes can be translocated between chromosomes but can nucleotide sequences be moved around within an individual gene? Could the following gene: MEN SAW OLD HEN Become: MSA WOL DHE NEN By ...
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Reason behind formation of positive supercoils during DNA replication/ transcription

When a twist is unwound without cutting the DNA strands or is removed by cutting the strand(s) and resealing, negative supercoils are introduced in the DNA. From Cell and Molecular Biology -Karp But ...
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What is the purpose of two cell divisions in meiosis?

At the moment, my thoughts are that the two cell divisions are necessary for recombination to occur, although I am not sure. I cannot really see why technically, the chromosome from each parent cannot ...
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How do point mutations arise from mistakes in DNA replication?

Hi! I'm trying to make sense of this illustration (from the textbook Biological Science by Scott Freeman). The general question is: How do point mutations arise from mistakes in DNA replication? If ...
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DNA & mRNA During Transcription

Just a simple, quick question: how are the mRNA and the template strand of the DNA structured during transcription? I've seen models and videos of them when they're both flat/straight (is that just ...
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540 views

What is open complex in E.coli DNA replication?

The E.coli DnaB helicase is essential for replication initiation from the chromosomal origin of replication ( oriC ) and is present in vivo as a protein complex with six monomers of the DnaC ATPase ...
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1answer
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At which point does a cell switch its function? [closed]

In a multi cellular organisms there are many cells of different functions. How / when does a cell change its function compared to its parent? Is it done by influence of other cells after its has been ...
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The relationship between the shape of the bacterial DNA and the blocking of replication machinery

I was reading a course about tolemers when I arrived to this phrase : [...] The ends of a linear DNA molecule cannot be replicated by the cellular replication machinery (which may be one reason why ...
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Performing PCR on samples whose DNA concentration is nul

Is it vain to perform a PCR on samples whose DNA concentration was measured as nul by a NanoDrop?
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474 views

dNTP concentration for reverse transcription from RNA to cDNA

Does it affect the results if I use the half of dNTP amount in a reaction that it says in my protocol? I usually use 4 microlitres per reaction and this time I did a mistake and I used 2. The final ...
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1answer
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Do mitochondria contain the genes to specify themselves?

My book says : "Mitochondria contain their own genetic material so when a cell divides, the mitochondria replicate themselves under the control of the nucleus." The book means that the mitochondria ...
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DNA replication: How many DNA polymerase molecules work in parallel?

Background research I am aware that DNA polymerase works in pairs, at least. This is to process both opposite stands of a given chromosome. The 3'-to-5' "leading strand", and 5'-to-3' "lagging strand"...
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Does DNA helicase or topoisomerase actually "unwind" DNA?

I am reading through my textbook (Genetics, Brooker 4th edition) and the summary it gives seems imprecise for the functionality of helicase and topoisomerase. The following is an exerpt: ...
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Why is there complementary base pairing for DNA?

Why is there complementary base pairing for DNA? Why can't A pair with C given that they can all form hydrogen bond?
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550 views

Role of dam methylase in bacteria

In bacteria, an enzyme called dam methylase (Deoxyadenosine methylase) methylates adenines (A) in the sequence GATC in the new strand formed after replication. What role does this methylation play? ...
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If we add only 1 primer in PCR [closed]

What would happen if we add only one primer, say forward primer, to PCR? (Image Credits: Wikipedia) As it is clear from the image that we need both forward and reverse primers to get it working (...
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DNA replication in E.coli

What is the difference between replication and to divide? My A level bio book says that it takes 20 min for E.coli to divide and in next page it's written that E.coli completes replication within ...
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Number of Chromatids in G1

I know that in G1, the number of chromosomes is 23 pairs, so 46. I assumed there were 46 chromatids too. Why is the number of chromatids in G1 actually 0, not 46? Thanks.
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From an information perspective, are both strands of DNA necessary?

I am learning about the genetic code, replication, and transcription, and I have a question about whether or not both strands of DNA are really "necessary". In replication, at a high level, we are ...
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Does any specific property decide which DNA strand acts as leading strand template?

Of the two strands of DNA, the one that unwinds in the 3' to 5' direction constitutes the leading strand template, with the other strand of course acting as the lagging strand template. Is there any ...
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Does cancer cells come from same process as evolution? [duplicate]

Here is how I understand it: DNA replication is not 100% perfect and error can happen, this error can be good(evolution) or bad(cancer properties). But its not the only source of cancer cells - DNA ...
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1answer
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How RNA primer on leading strand is removed during DNA replication and how the gap is filled? [closed]

Please can you explain me how the gap created by the removal of primer on 5'-3' leading strand is filled.