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Because that's how genetic variation works. SNPs are called single nucleotide polymorphisms for a reason: they are polymorphisms. This means that they are loci where different individuals will have a different nucleotide. This is precisely why they are studied and why we have databases of SNPs and the various genotypes they can manifest. Remember that ...


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Crossing over/synapsis in Prophase I of Meiosis I is when alleles are switched over from one non-sister homologous chromatid to another non-sister homologous chromatid. This happens before fertilization ever happens. Meiosis occurs even before birth in females in order to make gametes in the form of oocytes. In contrast, this frequently occurs in men who ...


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If you transfect cells with plasmid then these plasmids need to go into the nucleus (otherwise they wouldn't be transcribed). Getting the plasmid either happens during cell division (when the nucleus is not present) or by adding a signal sequence to the plasmid which induces the import into the nucleus through nuclear pores. The SV40 sequence is an example ...


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where does Protein come into play? : Genes code a protein. DNA is transcibed into messenger RNA (mRNA). mRNA is translated into protein What do you call Genes that are spliced together to form something new? : Genes are not spliced together. One single gene can consist of intrones (intervening sequences) and exones (expressed sequences). Transcribed ...


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Your answer to your titular question, How was the origin of CTVT parasitic cancer determined? is that cytogenic studies were done on the tumors. It arose in dogs and was logically assumed to be of dog origin, and was first characterized in 1876. The tumor cells were/are characterized by a rearranged karyotype, which is similar in tumors from in different ...


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I posted this on Reddit as well, so credit to km1116 for working this out. Here is his response which follows my original logic (though I'm not sure if he is right): female x male: w x se F1: wild-type females and white males F2: 1/4 white-eyed males, 3/16 wild-type males, 1/16 sepia males, 1/4 white-eyed females, 3/16 wild-type females, ...


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Thought I'd attempt to expand this into an answer, THOUGH THIS IS IN NO WAY MEANT TO SUGGEST YOU SHOULD ACTUALLY TRY THIS. THERE MAY BE LEGAL ISSUES INVOLVED IN CREATING A GENETICALLY MODIFIED ORGANISM, EVEN A HARMLESS ONE, DEPENDING ON YOUR LOCATION. SOME OF THE CHEMICALS REQUIRED TO HANDLE DNA ARE DANGEROUS, AND SHOULD ONLY BE HANDLED IN A FUME HOOD AND ...


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There is an interesting way to look at this question. By definition, two individuals are related only if they have a common ancestor. (If you mean something else by it, please correct me. For completeness, I include the trivial case in this: that is, I regard you as one of your own ancestors.) So your question can be inverted: it is really asking after how ...


3

Transformation underpins a lot of lab modern projects. This will be a very unsatisfying answer, and this wikipedia entry explains why. The time, and success, of bacterial transformation of competent cells varies greatly depending on a few things mainly: the length of nucleic acid sequence for insertion (or more accurately, the plasmid) the species of ...


2

Height This is just a single example, but "height" has received a lot of GWAS (genome-wide association study) attention, and last year the GIANT consortium published results of an analysis on 250,000 people looking at the genetic influences of height [1]. Using just 2,000 genetic variants they could statistically account for 20% of the phenotypic ...


2

Welcome to Biology.SE. First off, .. I'm assuming insects are at an earlier evolutionary stage than humans It is not the core of your question but still I want to point to this sentence. What is an evolutionary stage? Does it really mean something to you? What is sure is that a given insect individual or a given human both have evolved for exactly the ...


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Mendelian segregation is defined on the Nature site, and I quote: The Principle of Segregation describes how pairs of gene variants are separated into reproductive cells. The segregation of gene variants, called alleles, and their corresponding traits was first observed by Gregor Mendel in 1865. Mendel was studying genetics by performing mating crosses ...


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Interestingly the answer is yes. The problem with parallel strands is that the DNA is not pairing in the known way it does when it is combined anti-parallel (or Watson-Crick-pairs). I have found different images illustrating the problems: Both images are from this blog post (originally from a publication cited there which is not available online). Both ...


2

A group of tightly linked genes that are involved in similar molecular pathway are called supergenes. For the pleasure to formulate a slight opposition to @shigeta's answer, I will give some examples of supergenes in eukaryotes. In Primula, heterostyly is controlled by a supergene. In Papilio memno, mimicry is controlled by a supergene. In some species of ...


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TL;DR: Ubiquitin. Occasional occurrence of paternal inheritance of mtDNA has been suggested in mammals including humans. Clearly, spermatozoa have mitochondria; they make the energy needed for motility. Paternal mitochondrial DNA (mtDNA) does enter oocytes. It is a persisting fallacy that only maternal mtDNA is present in humans because only oocyte ...


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...would then be his offspring at risk? Why? No. Generally speaking, fathers do not pass on their mtDNA (Mitochondrial DNA). Why? Because the mitochondria present in oocytes (egg cell) is the mother's, as every oocyte directly inherits the mother's mitochondria when they are made in the reproductive organs. The mitochondria that the sperm from the ...


1

I wouldn't expect different methods to give the same results. Further, why are you even testing non-normalized datasets, the results of that are completely and utterly useless for any purpose other than showing that normalization is important. In addition, an T-test is a special case of an ANOVA (and of course limma is itself using a moderated T-test, though ...


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There are many other methods that are used for transfecting cells in culture. These include: Cationic lipid mediated (as mentioned by user137) Calcium Phosphate mediated transfection Biolistic methods Electroporation Newer techniques include optical transfection (using lasers to bore a hole through membrane) and impalefection (using nanotubes). Wikipedia ...


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Yes. The research team, led by the Durham Centre for Crop Improvement Technology, and including experts at the University of Nottingham, Rothamsted Research and the University of Warwick, have discovered that plants have the natural ability to regulate their growth independently of Gibberellin, particularly during times of environmental stress. They ...


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Oxytocin It has been shown that oxytocin signaling helps in muscle regeneration by activating MAP Kinase/ERK pathway in skeletal muscles.[1] Oxytocin is also known to promote adult neurogenesis.[2] Myostatin It is a paralog of GDF and like GDF prevents hypertrophy of cardiac muscles.[3] Leptin Though leptin is not really connected to ageing but it ...


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A gene is dominant (lets call it B) when its presence in combination with a recessive allele (heterozygotic Bb) leads to the same phenotype as homozygotic BB. A recessive allele leads only to phenotypic expression when it is present twice (homozygotic bb). To illustrate this rather abstract definition of dominant and recessive alleles let's look at a ...


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Below are some insights about the evolution of dominance. It does not directly answers your question but understanding how it is thought to evolve also help understand the mechanism governing dominance relationship between alleles. There are several hypotheses about the evolution of dominance. It is important first of all, to note that empirical ...


1

There are several hypotheses about the evolution of dominance. It is important first of all, to note that empirical observations show that beneficial alleles tend to be more dominant than detrimental alleles. Among the two main hypotheses to explain the evolution of dominance, one has been formulated by Ronald Fisher and one by Sewall Wright. Fisher's ...


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According to this website, it is a mnemonic for "lambda excision". I have also found this usage in scientific literature (Harami et al., 2013). However, neither of these sources reference anything and I cannot find any defining paper. Almost all papers simply refer to it as lexA. As far as I can find (it's difficult to dig up these old papers), this is how ...


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I'd go with Lambda Excision A. Terms like lex or rec often stand for what'd be termed a mnemonic, where for example rec may stand for recombination, or umu for UV mutator. The naming conventions can be difficult. Edit: A 1981 study by Roger Brent and Mark Ptashne notes some data from initial studies that showed the lexA repressor downregulated a number of ...


4

I'm not sure about the ubiquity of this but, in many animals, each each primary oocyte that undergoes oogenesis only produces one mature egg. The other products of meiosis are polar bodies, which are not fertilised. These cells often degenerate but can sometimes play supportive roles in embryogenesis. To answer your question, each mature egg is ...


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While your question asking about birds, reptiles and fish (oh my!) may be too broad, hopefully looking at frog oogenesis can show some differences in large offspring number v. small offspring number. Some frogs even give birth to live offspring (Iskandar et al. 2014). Much of this explanation can be found in Developmental Biology, 6th edition by Gilbert ...


1

Your confusion comes from the inconsistent terminology in the literature. The attachement of the spindles to the chromosomes happens in the Prometaphase [1, 2]. The name already suggests that this is not one of the classical phases is cell division, but lies somewhere between Pro- and metaphase. Wikipedia states: Prometaphase is sometimes simply included ...


2

IMO irrespective of country and level (undergrad/Masters), if you can run a job on a High Performance Computing cluster or a supercomputer, you should mention that on your resume. And sure, you can use that in your statement, especially given the fact that not many have access to it, you had the rare opportunity and made full use of it. In my experience, I ...


1

If one looks at the sequence map in detail, at the fusion point we find both telomere and pre-telomere sequences. And what is particularly compelling, is that these main groups occur in the correct order. That is, first you see a pre-telomere sequence, then a telomere sequence. Then we see the telomeres inverted and the inverted pre-telomeres after that. ...



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