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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Why does Taq polymerase add 3' adenine overhangs?

Is there a mechanism for the preference of Taq polymerase to add a non-templated 3' adenine (overhang) instead of other bases?
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28 views

How Did They Know What To Do ? And Cellular Identification [closed]

So this is regarding Science, generally, it has influence throughout each section science. How did the early age Scientists etc. knew what is to be done to achieve a certain thing ? And by that, I ...
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1answer
657 views

Why is DNA double stranded and RNA single stranded? [closed]

Why is DNA present as a double helix structure and RNA as a single helix? What causes the difference between them? What are the practical physiological differences between dsDNA and ssRNA? How are the ...
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34 views

Mutagenic Agent [closed]

This was a passage in University Degree Genetic Journal that confused me. DNA base pairs are more susceptible to mutagenic agents, so this reduces the chances of spontaneous mutations happening ...
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30 views

Determine OTU identity using Blastn full database or organism specific database?

I am seeking opinions on the best way to determine OTU identity using Blastn. Would the best way to identify an OTU be to blast the OTU to the full nr/nt Nucleotide collection or to blast your OTU to ...
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73 views

What is the meaning of the “d(…)2” notation when writing a DNA sequence?

When the sequence of a DNA oligo is written as d(CGCTAGCG)2 what is the meaning of the d(...)2? Why would it not simply be ...
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1answer
28 views

Pooling already extracted dna?

I had ethanol precipitated a large amount of DNA (2ml) and had to split the sample in half to spin down because only the microcentrifuge has the correct rotor to spin that fast. I want to get as ...
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1answer
75 views

How to improve DNA extraction

I am using the following protocol to extract chromosomal DNA from bananas: Cut up one banana into small pieces, approximately (1 cm3) Add ½ a cup of warm salt water and the banana pieces into the ...
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2answers
159 views

if sperm contains only 50% of someone's DNA how can it be used to identify someone?

Is DNA so unique that 50% of it is enough to identify a single person?
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17 views

Strand directed mismatch repair system?

In SDM (strand directed mismatch repair), random correction of DNA (correction of template strand) is not right. For example if G (from template strand) gets joined with the T (it should have actually ...
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0answers
213 views

Construct a restriction map of a linear fragment of DNA using the following data?

I've attempted to do the single digests, and the double digests, but cannot complete the map.... I've attached what I've done so far DNA Sizes of Fragments (bp) uncut DNA 900 DNA cut with EcoRI ...
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26 views

Do eukaryotes assimilate DNA that is floating in the extracellular membrane?

Prokayotes, which replicate primarily using binary fission, don't get much genetic diversity. For this reason, they take in any genetic material they encounter, in a gambit to help them better adapt ...
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29 views

DNA binding Domain [closed]

How to say whether a specific amino acid in a protein is binding to DNA or not from sequence alone and what are the features or characteristics to be considered?
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20 views

Do you have a comprehensive protocol using xGen blocking oligo? [closed]

Specifically used with genomic DNA and to help prevent non-specific binding
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1answer
92 views

What is two-start or zigzag model of 30 nm chromatin fibre?

I read some webpages describing the two-start model but could not get it. I'll be obliged if someone helped me understand the topic. The websites I have been through are: 1.http://www.nature.com/nrm/...
4
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1answer
119 views

What is positive and negative supercoiling?

Is the following correct? Positive supercoiling = the coiling of DNA helix (B-DNA) on itself during intesified coiling of the two DNA stands in right handed direction negative supercoiling = the ...
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1answer
130 views
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68 views

How do the major and minor grooves in the DNA helix arise?

I understand that they arise due to the pairing of bases of two opposite stands and are sites through which important proteins needed for replication and transcription of DNA interact. But I don't get ...
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0answers
20 views

From DNA to final traits of microorganisms? [closed]

From the answer of this topic, could someone indicate me a book or article about how DNA set the phenotype of microorganisms? For example, showing how DNA changes the shape of such a cell or how DNA ...
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27 views

Color of DNA, available absorption energy levels of DNA molecule, mutations

I have done a couple of DNA separations and observe that the clumped strands of DNA are white. Is that an artifact of the chemicals used in standard separations? Or is it indeed the case that the DNA ...
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3answers
1k views

Is Chargaff's rule really applicable?

Chargaff's rules states that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to ...
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28 views

Hydrogen bonding and the blocking thereof in nucleic acids during nuclear processes

In transcription, RNA polymerase unwinds the DNA double helix and begins attaching RNA nucleotides to the template strand. In its wake, the DNA double helix closes back—this is only natural, seeing as ...
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1answer
57 views

Does DNA polymerase I require a $3^\prime$ end?

DNA polymerase III adds nucleotides in the $5^\prime \rightarrow 3^\prime$ direction because it can only add nucleotides to the $3^\prime$ end of the previous nucleotide. This is why it requires a ...
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0answers
23 views

Infer type of nucleic acid based on number of nucleosides

Lets say we analysed a nucleic acid and found out that it had 20% Adenosine, 25% Guanosine, 40% Thymine and 15% Cytosine. We know that A always pairs with T and G with C. So, based on these numbers, ...
3
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1answer
78 views

Distinguishing Father from Brother

Given the (non-identical) DNA sequences of two men and the knowledge that the second man is either the father, brother, or son of the first man, is the DNA useful in determining which of these three ...
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21 views

Separate replication origin and terminus vs making them one and the same

The classical picture of bacterial reproduction has a replication origin on one side of the circular chromosome and a replication termination area on the opposite end. This essentially creates two ...
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2answers
248 views

Is the DNA different in each type of cell? What DNA is passed to offspring?

Our body contains many different types of cells and each of those cells have their own DNA (correct me if wrong) like skin cells their own DNA that makes them skin cells instead of muscle cells. So ...
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1answer
91 views

How many Watson-Crick + Hoogsteen triple base pair combinations are there?

Are these triple base pairs the only Watson-Crick + Hoogsteen triple base pairs possible? Furthermore, are TAA and TAT mixed up? This image is from Wikipedia, so it's possible that it's erroneous.
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24 views

Transgenic Plant-Gene source for introduction into host organism

Let's say the plant-gene itself is known, i.e. the exact neucleotide sequence is available in a gene bank (originally sequenced from a tree sample extracted RNA). Previous work has already successfuly ...
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43 views

Was the frequency of mutations more during primitive earth due to radioactivity?

Primitive earth was more radioactive (or was it really?) according to radiometric analysis of C14 which suddenly appeared at 4250 million years in the Hadeon eon. Is it possible that ancient high ...
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1answer
55 views

What does “~mitochondrial DNA ~bp linear DNA” means?

I'm surfing NCBI website -Nucleotide- to find some examples of real DNA sequences to use in my small homework project. My question is related to the title of a DNA sequence below: Sus scrofa ...
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1answer
35 views

BWA-MEM single strand or doublestrand alignment

In whole genome secondary analysis does BWA-MEM use a double stranded fasta reference or are reads aligned to only one, single stranded fasta reference?
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1answer
40 views

DNA Topology. Question on twists and writhes

Hi guys there is a question which has been driving me crazy ever since I saw this video(https://youtu.be/az2c6UbEdug). At 4:50 the guy says that when a right-handed circular DNA starts forming a right ...
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1answer
45 views

Why do Major and Minor grooves exist in dna strands? [closed]

I've been trying to find what causes the periodic appearance of major and minor grooves in DNA but have not yet been successful. Geometrical explanations would also be appreciated as I cannot ...
3
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1answer
53 views

How does the splicing enzyme recognize where to splice the introns?

When the DNA from the nucleus is transcribed to an mRNA, the mRNA is spliced by an enzyme before it goes outside through the nuclear pore. What is the name of this enzyme and how does it recognize ...
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1answer
178 views

Is DNA replaced after organ donation?

If an organ from person A is transplanted to a new human body B, is it possible that we can detect A's DNA in B? How long until the organ's DNA is replaced by B's DNA so that we are no longer able to ...
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2answers
48 views

“Prime” structure of DNA Double Helix: Confusion

In this video on DNA replication, the diagram shows the unwound DNA as still being anti-parallel, but the first diagram in this post on Biology SE shows that the individual strands are 5'____5' and 3'...
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1answer
114 views

The Semi-Conservative Model of DNA Replication: Question

My Campbell's Biology textbook contains the following diagram related to the semi-conservative model of DNA replication proposed by Watson and Crick. I have highlighted where my confusion arises in ...
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33 views

Is DNA transcription inactive during mitosis ie no proteins are made? How does the cell survive?

I've read that during mitosis, DNA exists as heterochromatin, a form that is unable to be accessed for transcription. Does this mean no new proteins are made during what can be 20% of a cell's life? ...
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1answer
35 views

Constant or variable number of chiasmata during recombination?

During recombination, is the number of chiasmata consistent for each gamete and are the chiasmata regions consistent within a single organism?
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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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Where can one find completed and processed Hi-C datasets?

I and a statistics graduate student at UCR, and I am working on Optimal Binning schemes and peak detection in Hi-C data analysis (a dataset that conveys information about proximity of a DNA strand ...
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1answer
54 views

Are nucleotides at the ends of DNA stripped on aging?

I had the following understanding (now after reading a popular science article seeming wrong understanding): DNA in (regular) cells (in human and some other organisms) are protected by telomers. ...
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1answer
26 views

DNA extraction for LAMP assay

I am trying to set up a LAMP assay (Loop-mediated isothermal amplification) for the detection of E.coli. I was told that EDTA can chelate the Mg in my reaction and thus prevent the assay from working ...
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20 views

Why only human have noticeable difference in face? [duplicate]

Our facial appearance is pretty much different from each other unless we are talking about twin. Credit goes to crossing over of chromosome. But why can't we distinguish between other animals of same ...
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1answer
260 views

Why are the genomes of Humans 99.5% the same?

Human's DNA sequence is said to be roughly 99.5% equal. As far as I understand, this means that if I walked up to you and compared our DNA, the sequence of base pairs would be 99.5% the same. My ...
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0answers
11 views

final control prior to transfecting an expression vector into a mammalian cell?

I have been asked a general question: Once I have cloned a full-length cDNA into an expression vector, what final important control must I do before I transfect this into an embryonic stem cell line? ...
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72 views

Which DNA fragments do not have expected sizes on this gel electrophoresis?

The problem is such: After performing a PCR, the vector carrying the PCR fragment with two restriction enzymes (Nhe1 and Asc1). The DNA samples were then separated using agrose gel electrophoresis ...
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1answer
115 views

why is cellulase not found in animals? [closed]

As it is really beneficial for all organisms, why are animals, especially mammals (I don't know about other vertebrates) unable to synthesize cellulase enzyme in their body? Is it linked to some DNA ...
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3answers
201 views

Why don't housekeeping genes have TATA Box regions in their promoter sequences?

Housekeeping genes are genes that are continuously transcribed. Like all other genes they have promoter sequences, but they don't have TATA box sequences that are used to specify from where ...