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If the Cold Spring Harbor Laboratory is considered a reputable source (it should be), you can check out their Defining the gene page which has an overview of the beads-on-a-string theory, and how it was disproved by Seymour Benzer. You could also try to find Benzer's original paper, although it doesnt seem to be available online. Related and possibly ...


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Actually, Cas9 system might be a possible method to achieve your aim in the future, research teams are trying to utilize cas9 in vivo, which means maybe someday we can doing some genetic modification in body cell precisely. However, this is only a future direction and we still can not say its fit for a knockout.(Patrick D. Hsu, Eric S. Lander, and Feng ...


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"Evolving from another species" versus "Most Recent Common Ancestor (MRCA)" One cannot say from two extant species that one evolved from the other. It just doesn't make any sense. It is not only true for cats and chimpanzee but it is true for any pair of extant species. One extant species has never evolved from another extant species. However, one can say ...


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Cats and monkeys have a common ancestor, both are placental mammals, so at the very least they must have both evolved from the first placental mammal. Cats are members of the Laurasiatheria group and primates are members of Euarchontoglires. These groups of mammals probably split off from each other about 100 millionish years ago. For more information about ...


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Richard Dawkins discusses this in his book The Greatest Show on Earth: The Evidence for Evolution Bacteria and other microorganisms, specifically Archaea, are able to exchange in a sort of 'copy and paste' genetic exchange that differs wildly from sexual reproduction. They can even exchange genes with other distantly related species. This, coupled with ...


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You are asking about two different processes: turnover (degradation) of mRNA and turnover of proteins. In a typical mammalian cell the mRNA half-lives of stable messages approach the length of the cell cycle (e.g. 24 hr). One mRNA could be translated around the clock if needed. The resulting proteins will also have a measurable half-life, and that will vary ...


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http://www.livescience.com/46986-human-genome-junk-dna.html Microorganisms are often able to adapt to new environments quickly, but they lack the specialized functions of macro-organisms. Consider that the micro-organisms of macro-organisms have developed to form machinery that builds solutions to problems, rather than being retrofitted themselves to ...


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As @canadianer pointed out in the comments section flanking sequence is a sequence that is immediately near the target on either side. Since chimps and humans are closely related and the sequence different is minimal (according to this paper its approx 4% for the entire genome) so using human primers is totally fine. Now if take a look at the picture of ...


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As with all serious scientific result GWAS results need to validated by others. In this case it think is extremely important because these studies link mutations to diseases or in more general given genotypes to phenotypes, thus pointing out possible causes. So validating these results with the use of independent "samples" is indeed crucial. But as I said ...


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mtDNA is present in a much higher copy number per cell than nuclear DNA. According to this paper, there are approximately 4000 or so mitochondrial DNA copies per human muscle cell. copy number of mtDNA per diploid nuclear genome in myocardium was 6970 ± 920, significantly higher than that in skeletal muscle, 3650 ± 620 (P = 0.006). This makes it far ...


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If you're looking for a strictly and directly DNA-DNA mediated effect (no histones, no transcription involved) I'd look for sequence effects on chromatin remodelling, modulating access of transcription factors (TFs) to their elements. Something about this might be in this paper: Szerlong, H. J., & Hansen, J. C. (2011). Nucleosome distribution and linker ...


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Deinococcus radiodurans did not "develop resistance to mutations". It is able to repair its chromosome when scatered in pieces by radiations or desiccation, while other bacteria would die in such conditions. So this is adaptive in extreme environments, such as deserts (where it has evolved) or canned corned beef (where it was discovered).


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So in a pedigree, Standardized Human Pedigree Nomenclature: Update and Assessment of the Recommendations of the National Society of Genetic Counselors notes that these "nodes" in the pedigree are the "individual symbol" denoting individuals. Although, when you read it, you'd read "Male," "Female," "Gender Unspecified," etc. instead of individual symbol.


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The growth of blood vessels is called angiogenesis. This process occures during embrional development, tissue repair, and even tumor formation (in fact this is a crucial step for tumors to survive). This Nature review provides great overview of the process, I'll try and briefly summarize things: In general large arteries grow circumferential to keep up ...


2

From the pheno-geno map and the genotypes frequencies, you have the whole distribution of phenotypes in your population. The mean of the phenoype $n$, $P_n$ is the $$\bar P_n = \sum f_{G_i} P_{G_i}$$ , where $f_{G_i}$ is the proportions of individuals having genotype $G_i$ and $P_{G_i}$ is the phenotype of the individuals with genotype $G_i$. Therefore, ...


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I assume these are all carcinogenic mutations. Because some them are clearly recessive loss-of-function mutations (like loss of transcript), you can conclude that the function of the gene consists of "holding back cancer". When these mutations occur, they can generally be complemented by a healthy allele on the sister chromosome. Oncogenes on the other ...


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There are several subconcepts within the concept of robustness. Several definitions exist for all of these concepts and I am just suggesting one variant of the possible definitions below. Mutational robustness Might be defined as a function of the mean and variance of the distribution of mutational effects. Environmental robustness Might be defined as ...


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So cryopreservation would be the long-term mode of storage, and you'd do something like store your sample in a cryonic freezer supplied w/ liquid nitrogen at -196C. Cellgro provides some recommendations for cryopreservation here. Keep in mind, cryonic freezers are typically pricey, but broady, the idea is you need to keep your cells at the right temperature, ...


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Short answer: Pointers already exist within the genome, in terms of transcription elements (such as repressor/activator systems). These systems can remotely activate a specific gene for transcription based on concentrations of specific chemicals within the cell. The problem with LINEs are that they are thought to be ancient retroviruses which lost their ...


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What if imprinted regions are immune to being wiped? Also, you may be confusing DNA methylation, and histone methylation (?). Classical biochemistry posits that DNA methylation states can be transmitted from a dividing mother cell to both daughter cells because after DNA replication the two daughter chromosomes will each be hemi-methylated, and a DNA ...


2

If you have genomic imprinting then $k^n=m^2$ (with k=m and n=2 because of diploidy) is correct as inheriting a from the father and b from the mother (i.e. ab) is not equivalent to inheriting b from the father and a from the mother (i.e. ba). For 3 alleles (a,b,c) you have 9 possible genotypes (aa,ab,ac,ba,bb,bc,ca,cb,cc). Under no genomic imprinting, ab ...


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A: wild-type allele / a: color blind allele Because color blindness is recessive and X-linked your assumption $p=F(a)=4\%$ is correct as men do only have one copy of the allele. Subsequently $F(A)=q=1-p=0.96$ is also correct. Therefore: a) $F(Aa)=2pq=7.68\%$ is correct and b) is wrong, a is the color blind allele and $F(a)=0.04$ therefore it's ...


1

If you're looking at evolutionary timescales, then the only available source of information is the target organism's genome sequence. At least some of the methods of horizontal gene transfer you mention leave a distinctive signature in the genome. For example, retrovirus particles that have become incorporated into the human genome are easily identified by ...


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SNPs are much denser than RFLPs and VNTRs therefore the DNA resolution is much greater with SNPs. VNTRs were historically used for linkage mapping while SNPs allowed for association studies (e.g. GWA studies). Therefore your question goes down to what are the differences between linkage mapping and association studies. They are both forward genetic methods ...


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A pre-tRNA is transcribed from tRNA genes in DNA by RNA polymerase III. Processing occurs in the nucleus, where a 5' sequence is cleaved by RNase P, the 3's CCA motif is added, and ~10% of the nucleotides are substituted. The tRNA are transported out via the pore complexes. Aminoacyl-tRNA synthetase enzymes attach amino acids in the cytoplasm in a 2-step ...


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If you want to have random integration you need to find gRNA sequences that are nonspecific ; everything built for CRISPR so far has been geared towards precise integration, not random integration. Talk to an informatician about pulling out non-unique sequences from the human genome. You will then need to clone out a library of 20nt sequences that end with ...


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When you travel to different time zones, your circadian clock will be off (incorrect). The reason your circadian clock will be off is because your body has adapted to the time zone you are from. When you enter a new time zone, your circadian clock will still be functioning on the old the time zone. If the time zone difference is $\pm 12$ hours, this is a ...


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Frequency of allele for Haemophilia (q) = 0.4 Frequency of normal allele (p) = 0.6 Cross between Heterozygote female and hemophiliac male by punnett square: Probability of hemophiliac daughter = 0.5 P(hemophiliac male) = 0.4 P(heterozygote female) = 2pq = 2 × 0.4 × 0.6 = 0.48 P(hetero female+hemophiliac male+hemophiliac daughter) = 0.5 × 0.4 × 0.48 = ...


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Question 1: The phenomena you describe in which it matters whether you have one or two copies of an allele (e.g., the AA phenotype being different than the Aa phenotype) are known as dominance effects. Dominance effects can interact with epistatic effects (in which the phenotypic effect of one locus depends on the genotype at the another locus). One good ...


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T-cell migration to the brain is very limited and occurs at a very low level in healthy conditions, however during diseases the number of T cells passing through the blood-brain barrier is elevate due to increased expression of traffic signals and adhesive molecules. I've found two good articles on how T-cells migrate through blood-brain barrier: J Neural ...


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Centi-Morgan (cM) is based on observation not precise measurements. Now since double crossing-overs (and actually any arbitrary even number of crossing-overs) revert gene combination to the parental type, resulting lower recombinant frequency. So in your case since the chance (or the frequency if you wish) for double COs is 0.6%, you have to subtract this ...


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A paper was published about a week ago in Nature Biotechnology and adresses your question, Maruyama T et al., 2015. I must say I found the authors' strategy extremely clever. It is not about increasing efficiency by reducing specificity, but simply increasing efficiency (which is your ultimate goal anyway). What the authors did was to inhibit nonhomologous ...


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I'm going to preface this answer with the disclaimer that I have never used CRISPR/Cas, and there is a fair amount of speculation here. But I think that efficient CRISPR mediated knock-in probably has three parts, targeting, integration, and selection. The targeting is accomplished by the guide RNA, which is often introduced as DNA on the same plasmid that ...


3

It is possible but extremely unlikely. When a base undergoes tautomeric shift the DNA does not contain a mutation yet, just an unmatched pair. The mutation will only becomes inscribed into the DNA permanently after the DNA is replicated or wrongly repaired. In order to reverse the mutation you would need to provoke a chemical change to that specific base ...


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Ns are not non-recombinant at the genomic level. What you know is that they do not show recombination events at the risk allele locus as subjects carrying the marker A1 show signs of the disease and similarly healthy subject do not carry the marker A1. Hence they are called non-recombinant. On top of that 3rd generation subjects (excepted III6) show ...


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First of all I am not sure if your examples are per se correct. But they might also be an additional bonus. Secondly, I would like to refer to two articles: "Polyploidy" and "The advantages and disadvantages of being polyploid". One of the main benefits could be allowing organisms long-term evolutionary flexibility. Often adapted polyploids can undergo a ...


4

Either the gene is present in multiple copies (especially possible if it is in a plasmid) or multiple RNA polymerases are transcribing it, each beginning from the start site one after the other with some amount of time delay, much like multiple ribosomes translate the same mRNA to increase rate of protein production.


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Lets assume for simplicity that DNA is globally subjected to the same mutation rate (which is probably not a fully correct assumption). Now let take a DNA region which is functional (what you meant by giving a fitness benefit), mutations in this region will occur as anywhere else in the genome. Some mutations will be deleterious and reduce the fitness of ...


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Multiple RNA Polymerase transcription complexes engaged on the lacZ gene at the same time, staggered along the gene.


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I found the explanation at this site helpful: http://www.ndsu.edu/pubweb/~mcclean/plsc431/linkage/linkage1.htm I don't have a clear sense of what you mean when you ask about assorted phenotypes occurring before recombination ("crossover"). All of your examples deal with diploid organisms. If they are multicellular then the cells that can undergo meiosis are ...


3

Conjugation occurs between cells of the same species too. For this to occur cell have to be close to each other. Now, if you have an isolated population of bacteria that never gets in contact with an F+ bacteria then this population would stay F-. Also not all conjugation events are successful, mechanical perturbations can disrupt the pilus through which ...


-1

Your theoretical understanding of the ramifications of X-chromosome inactivation is excellent (e.g., the two situations you described). However, it is important to consider the size of the resulting clones. At that early stage of embryogenesis only ~ half (or less) of those cells will go on to contribute to the fetus, the rest will form the placenta. Also ...


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Parent 1 and 2 have each 5 possible genotypes (OO, AO, BB, BO and AB). Here a Punnett square with each possibilities. I highlighted the possible parent genotypes. The total number of possible crosses is exactly 21. Note that here A = Ia, B = Ib and O = i. OOxBB,OOxBO,OOxAB AOxBB,AOxBO,AOxAB BBxOO,BBxAO,BBxBB,BBxBO,BBxAB BOxOO,BOxBB,BOxAO,BOxBO,BOxAB ...


4

Claudia's dad is not a taster, so he is tt. He passes one allele on to his daughter. Since he is homozygous, he can only pass t. Claudia is a taster, so she must have the dominant allele from her mother, who is also a taster. Thus, Claudia is Tt.



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