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Questions tagged [dna-replication]

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

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4answers
107 views

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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griffith's experiment if both s and r strains are added can the r strain be isolated from blood of the mice

in the Griffith's experiment for transformation principle, 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 the dead mice....
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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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1answer
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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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1answer
64 views

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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1answer
72 views

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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2answers
256 views

Typical DNA replication times

Just out of curiosity (I am completely strange to biology), as I have been unable to find this info on the internet: How long does the whole DNA replication process take? (say, the replication of a ...
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0answers
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Primer design: Calculating free energy for secondary structure

I'm attempting to automate primer design (specifically, primers for RPA, which requires longer primers [~30-35 nc] than PCR), and need to figure out how to calculate the free energy of a primer pair ...
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1answer
63 views

PCR and Semiconservative replication

Why does PCR use heat as opposed to helicase like in semi-conservative replication in order to separate the double DNA strand?
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0answers
92 views

Can DNA be transferred from one person to another [closed]

kissing, handshaking, blood transmission, sexual intercourse etc,through which of these DNA can be transferred to another person ?
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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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2answers
315 views

Chemistry of phosphodiester bond formation by DNA polymerase

As I'm teaching General Biology to my college students, I realized that I don't fully understand how a 3-P nucleotide like ATP is broken down to be incorporated into DNA during replication. How does ...
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1answer
52 views

Are there any particular chemicals that initiate either DNA replication or Transcription ? [closed]

When does the nucleus of a cell "know" when to bind DNA nucleotides ( for Replication ) or RNA nucleotides ( for Transcription ). From what i read, they're both structurally different and free ...
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1answer
262 views

Can mitochondria become cancerous?

Given that mitochondria have their own DNA and can replicate independently, can they ever become cancerous? For example, could a mutation in their DNA cause them to rapidly replicate, ultimately ...
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1answer
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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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2answers
92 views

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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0answers
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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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2answers
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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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1answer
150 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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1answer
91 views

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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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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1answer
1k 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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2answers
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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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1answer
923 views

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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4answers
622 views

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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1answer
867 views

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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1answer
194 views

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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3answers
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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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1answer
298 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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2k 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
52 views

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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0answers
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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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611 views

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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1answer
812 views

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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1answer
703 views

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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1answer
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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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432 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 ...