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2

It is not unlikely that nicking is causing trouble. The question is if repeated freezing and thawing is causing the problem, there is an article which has been published in B.R.L. Focus in 1983 which disputes this effect. You can find the PDF with the article here, the article itself starts on page 10 in the PDF. On the other hand there is this paper ...


4

Here is what the data says. UK government must have had some scientific evidence when it settled on a 10 variable-length sections of genome for their database, SGM+. In one such variable sections, some people have 10 repeats of CTTT, others have 11, others have 12 etc. The largest of those fragments, at its maximum length, are about 350 base pairs. The US ...


3

When designing PCR primers we typically use a minimum length of 20 bases, because the probability of a sequence of N bases appearing by random is $\frac{1}{4^N}$, and $\frac{1}{4^{20}}$ is about 9x$10^{-13}$, or about 1 in a trillion. Since the human genome is a little over 3 billion bases long, a 20 base sequence should appear only once. However, most of an ...


7

Yes, this is possible (and I have done it uncounted number of times) - the method is called "Freeze and squeeze". What you basically do is to run the gel, cut out the band of interest (be careful with the UV light, it causes damage to your DNA and also sunburns, so wear appropriate shielding for your face), dissolve it in a buffer, then freeze it in liquid ...


4

That's a pretty neat video, I'll just give you some background information first. It's an illustration of the "trombone model" of DNA replication. The darker blue molecule is helicase, it unwinds the DNA and facilitates translocation (this is an ATP dependent process). The dark purple molecules are DNA polymerase, they catalyze DNA strand synthesis (an NTP ...


2

Did you try googling "splice site recognition sequences"? In general, the first two letters of the intron must be GT, the next three are often ARG. The last three letters of the acceptor site of the intron are virtually always YAG


1

RNA was almost certainly the first genetic molecule of inheritance. However, the single-stranded nature of RNA is not particularly stable and thus would not be reliable for the long-term storage of genetic information necessary for reproduction (and ultimately evolution). The necessary stability is provided by DNA. The question becomes, how did DNA evolve ...


3

Imagine you want to produce a widget. You have thousands of worker, but only one blueprint. Each worker needs the blueprint to build a widget (they're really forgetful and can't build from memory). So only one worker at a time can build your widgets. What you would do is to create copies of your blueprint and distribute them to your workers. That way ...


0

OK, I found this on Wikipedia. I probably should have checked there first! DNA has three primary attributes that allow it to be far better than RNA at encoding genetic information. First, it is normally double-stranded, so that there are a minimum of two copies of the information encoding each gene in every cell. Second, DNA has a much greater ...


2

First as you mentioned, which is I think the key thing, is that you need to clarify what DNA sample it is that you are observing in the gel. The best thing to do to ensure that you only have PCR generated DNA samples is that once your PCR is over, treat your DNA mixture with Dpn I enzyme, which cuts methylated DNA, which is essentially cellular DNA as they ...


1

This might be a good article to read: http://www.ncbi.nlm.nih.gov/pubmed/24497635 Robert Kerns's lab has been doing a lot of work on fluoroquinolines, so look into his other work as an entry to the literature. And apparently X-ray crystals have been done for at least parts of this complex. There is some evidence for fluoroquinolines binding to DNA, then ...


2

After you check your gel it would behoove you to check primers, preparation, the quality of the XNA itself, then proper electrophoresis levels and other mechanical failures. I would think improper resistance of the electrophoresis wiring would cause your problem.


3

Yes, that should be possible. And it is one of the ways antibodies work. It is already used as a treatment against rabies. There you get a dose of immunoglobulins directed against the rabies virus together with the vaccine. The immunoglobulins neutralize the virus. The same is possible when you vaccinate against the surface proteins which a virus uses to ...


6

There is one simple reason for that, your agarose gel is most likely too dense. Depending in the type of agarose, I would prepare a 0.5-0.6% gel at maximum. Synbio gives this list for "standard" agarose, which fits pretty good with my experiences. If you use low melting agarose, this table looks a bit different, as the gel matrix is not a dense. The ...


0

Here's a language metaphor. In a single language, words may be said or written across a spectrum of accents or spellings but have the same meaning. Likewise in a single species, genes (words) may exist in a spectrum of diversity (DNA sequence) but maintain the same meaning. So, when 2 species share "most of their DNA" they share most of the same genetic ...


1

The negative charge in DNA is localized to individual oxygen atoms in DNA. This negative charge is balanced by positive ions in the body. In the case of a magnet or molecules with a dipole, negative and positive magnetic field lines align to produce an overall magnetic field. DNA has many small dipole moments but none across the entire molecule. In the ...


8

DNA in the body is not available as a free molecule, it is organized around DNA binding proteins, mostly the histone octamers. These proteins carry positive charges (mostly from lysine side chains) which interact with the phosphate backbone of the DNA. It is like in the figure below, the charges play an important role in the tight packaging. See here for ...


2

Your cells have a high concentration of sodium ions that are positive. Other important cations are potassium and calcium. Additionally, many amino acids are positively charged at physiological pH. DNA is not the only source of negative charge in your body, other amino acids are negative, and most cell surfaces are negative as well. The interactions between ...


5

This has nothing to do with the proportion of the genome that is coding as suggested in another answers. The reason the figures are so different is because they are measuring different things. The chimp-human figure is measuring sequence similarity whilst the figure for kin are measuring gene similarity by descent. This gives two sources of difference in ...


8

When people say that siblings share half of their genes, they're talking about alleles, which are different versions of the same gene and generally differ slightly in nucleotide sequence. In essence, all humans share 100% of their genes (almost), but the number of shared alleles varies. Example: geneA, allele1: atgccc geneA, allele2: atgccg geneA, allele3: ...


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The human genome is composed of roughly 3 billion DNA bases called "nucleotides", typically represented as A, T, C, G. Genes are sequences of nucleotides that encode a protein; but they only comprise about 2% of the full genome. (http://en.wikipedia.org/wiki/Human_genome). Most components of cells are made of proteins. The rest of the genome is made up of ...



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