New answers tagged

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Ideally, DNA itself is the same in DNA-containing cell types. Cell type depends on expression, which depends on epigenetics. I.e. histone modification, DNA methylation, and few other mechanisms. Also, epigenetics is the mechanism for gene expression regulation. For example, it can silence (usually, methylate promoter regions) an expression of genes on one ...


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What I was taught by people in genomics is that "variation" is preferred for an allele that was not private to just one individual or family, but was found in pretty much unrelated individuals, while "mutation" is preferred for a very recently changed allele that is private to one individual or their family. Sometimes, it seems the "mutation" is preferred ...


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Good question! The term mutation can be used with two different meanings. Each definition can further be split into two different more detailed definitions. The reason for this slight mess is mainly historical. In short, a mutation can refer to An event narrow sense broad sense An allele definition based on ancestral/derived states definition based ...


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1) Does crossing over occur between gene loci, or can it occur within them? The cross-over events can happen within genes in introns and/or exons and still lead to viable gametes. The text is stating that it's the increased length from introns that increases the probability of a cross-over event there, which is basically true. This is simplified, and ...


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One or both pairs of homologous chromosomes could exchange genetic material during the process of crossing over. The number of cross-over events depends on the number of chiasmata. There are also ways for meiosis to occur with no exchange of genetic material between homologous chromosomes. The image you reference at uic.edu is incorrect. The purple arms ...


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I will clarify your question a little. We start with two men, Dave and John. We know Dave and John are related, either as brothers, or parent-child. Can we use genetics to work out their relationship? If Dave and John are brothers they will have the same mtDNA, the DNA in the mitochondria, because mitochondria are maternally inherited. They should have the ...


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Crossing over primarily happens because of homologous recombination (HR). From the molecular point of view, it can happen between any homologous regions and it is not necessary that an entire allele has to be crossed over. During the process of HR, a DNA double strand break occurs. This is followed by resection (exonucleolytic degradation of one of the ...


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These regions, if unannotated, are simply called intergenic regions. Sometimes, if a large section of chromatin is regulated by an enhancer/silencer/locus control element, then there are boundary elements that demarcate this chromatin region and prevent the spread of the chromatin state to neighbouring regions.


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Most cells in a human body contain a complete set of the genome, which is two sets of 23 chromosomes. Having two of each chromosome is called diploidy. Within an individual human the DNA is approximately identical in every cell. Different cells are produced by differential use of that DNA: certain genes are more (or less) highly expressed etc. You can read ...


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From what I can tell, you are not including the probability of the grandfather being a carrier (it could be the grandmother who is the carrier). Calculation should go like: P(Child is born with disorder) = P(II-2 is carrier) * P(I-2 is carrier) * P(II-3 is carrier) * P(III-2 is carrier) * P(Child is homozygous recessive) P(Child is born with disorder) = ...


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There's no technical definition for "genetic characterization". It is simply a phrase used by authors based on the normal meaning of the words: (1) having to do with genes and heredity, and (2) describing the essential character. Of course the bounds of the genetics and the essence of their nature are entirely in the eye of the author and reader, so no ...


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As Matej said, mutations in two different genes (or even a gene and a non-coding regulatory element) can lead to complementation and as they pointed out, the complementation test is designed to check if mutations are on separate genes or not. Molecular mechanisms that may lead to complementation (apart from Matej's example): The double mutation in two ...


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The main principle is that the loss-of-function mutations have to be on different genes and recessive. Source I wouldn't say they compensate each other. If either of them was in homozygous conformation, their effect would be full-shown. The thing on the molecular level is that often less than 50 % of the gene product is necessary for the gene to "work", to ...


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Yes, primitive earth was more exposed to radiation as a result of the Earth not having gaseous oxygen during the Hadean eon (which was formed after the oxygen catastrophe as a by-product of cyanobacteria's photosynthesis), which could form ozone and the ozone layer. As a result of the absence of the ozone layer, ultraviolet radiation would not have been ...


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No. But a strong correlation may nevertheless be an indicator for heritability (it makes it more likely). The reason is, that the correlation in the phenotype (birth weight) is not only due a correlation in the genotype but also a correlation in the environment of the child and its mother (culture, economical situation, genes, etc of their respective ...


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Certainly not yet - there is not yet any evidence that this can be used to correct specific deficiencies in an adult, though the in vivo applications are growing. In particular, an exciting recent advance is the opportunity to better understand carcinogenesis by 'editing in' certain known mutations into a mouse, say, that should cause a cancer, and watching ...


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I can think of two factors that would influence this, but there are probably more. 1) How do transposable elements (TE) get into the genome in the first place? The answer is both vertically and horizontally. Vertical transmission needs no explanation. Horizontal transmission of TE has been documented in several cases. In some cases, infectious agents ...


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There is a lot of confusion and conflicting / imprecise definitions of these terms. It's biology after all :) A mitogen is an agent that causes a cell to enter mitosis. This definition is pretty clear, and there is a good consensus about it. (Well technically, mitosis is not the same as cell division, but we will gloss over this distinction.) The term ...


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You can find a great article about this here. basically, these two groups are very similar in their effects, however they work through different pathways. Mitogens directly promote cell to get through G1 checkpoint through highering the activity of cyclin D/cdk4 (the complex needed to get through the checkpoint.) and according to the article above, also ...


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I don't think that's right. I think 102 would make sense, because you want 99 nucleotides to code for 33 amino acids and more more triplet to code for stop. Maybe the question writer didn't quite realize that the starting methionine counts as one of the 33 amino acids.


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Fixation is a process when one of the polymorphic alleles becomes fixed in the population gene pool due to genetic drift or natural selection and ceases to be polymorphic anymore. Therefore fixed substitution and SNP are two absolutely different concepts. So, the term “fixed single nucleotide polymorphism” seems to be oxymoron as it bears a contradiction. To ...


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BWA-mem (like most aligners), takes a normal single-stranded fasta file (I've never seen one with both strands listed) and aligns to both strand.


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You question is a bit unclear, and I think there might be a couple of mistakes in your inequalities. However, I think you are looking for the terms Overdominance (also called Heterozygote advantage) and Heterosis (also Hybrid vigor). Both of these concepts imply that heterozygotes and/or hybrids have a phenotype that lies outside of the range described by ...


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It is all explained here in Wikipedia. You are referring to Watson-Crick base pairs in the B-DNA structure.


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Infertility is defined as the inability to conceive after one year or longer of intercourse without the use of contraception or therapeutic donor artificial insemination. That definition does not include a state of permanence. That is, with treatment, fertility can indeed be achieved in many cases. You may want to consider the term sterility as a ...


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Both genes and alleles are sequences of DNA. A gene will code for a trait, say hair colour, while an allele will be the variants of that gene (say the alleles coding for blonde, brown, black, and red hair). It's almost like cookbooks: two cookbooks (the DNA) might have a recipe (gene) for bread but they use slightly different instructions (alleles) ...


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Alleles are basically subtypes of a gene. At the time of Mendel, the molecular nature of inheritance was not known so the original definition of gene refers to "some" inheritable molecular entity inside the organism that is responsible for a trait. Alleles are different "flavours" of a given gene. For example there is a gene for flower colour, there can be ...


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The major hurdle for novel treatments to make it into humans is the assessment of its merits and added value over existing, proven treatments. And more importantly, the safety for humans has to be validated to a sufficient extent. The notorious from bench to bedside (Goldblatt & Lee, 2010) bottle neck. To answer your questions: Technically, going from ...


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The vector used in this study is based on the herpes simplex virus genome (HSV). Wildtype HSV mainly infects sensory neurons. After infection, it resides in a latent state in the nervous systems of the host for a lifetime. The viral genome persists in the cell, without integrating into the host genome (Marconi et al., 2000). The article cited is devoid of ...


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I believe the reason you are having trouble understanding the concept is due to a poor usage of colors in the diagram. Don't focus on the colors, but on the concept. It's the same for both replication events. Each strand of a double helix is used as a template to make a new complimentary strand, giving rise to two new DNA helices from the original. In each ...


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Briefly, because remi.b gives a lot of good detail about this in his answer, (narrow sense) heritability is essentially a measure of how much of the phenotypic variance is explained by (additive) genetic variance. Phenotype (P) in an individual is the result of genetic (G) and environmental effects (E). $P = G + E$ Thus the within-population variance in ...


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In the first cross, if we talk of a single mating pair of flies, one parent is red eyed, one is white eyed. The ambiguity about sex leaves two options, 1) red eyed male crossed to white eyed female, 2) white eyed male cross to red eyed female. If it were the former (red eye male) then the mother must have two X chromosomes both of which have do not carry the ...


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I think the text is slightly misleading. But before going into the detail genetics of eye color let's answer your first question. First, wouldn't recombination scramble the eye color alleles among the sex chromosomes? Two X chromosomes do recombine but one X and one Y chromosome do not recombine (to the exception of the so-called pseudo'autosomal region). ...


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There is a large amount of variation in the distribution and number of chiasmata or crossing overs (COs). The total number of chiasmata per cell can vary within the same organism. Where chiasmata occur along the chromosome is also not consistent cell to cell. Hotspots are 1-2kb regions that experience elevated recombination compared to neighboring genomic ...


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This question is interesting. First of all, I recommend you to look a little bit about the most popular definitions of species and, more importantly, how speciation can occur. I can picture a problem of hybridization when I think of your question. Since speciation takes many (plentiful) generations to happen, and as I can remember, can involve sympatric ...


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Chaotropic agents are cosolutes that can disrupt the hydrogen bonding network between water molecules and reduce the stability of the native state of proteins by weakening the hydrophobic effect. a chaotropic agent reduces the amount of order in the structure of a protein formed by water molecules, both in the bulk and the hydration shells around hydrophobic ...


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The answer is incomplete dominance. It can't be codominance, because codiminance involves both phenotypes being expressed in different parts of the organism: you would end up with red and yellow spotted flowers. It obviously isn't complete dominance, because the red x yellow cross produces orange flowers. Knowing that it has to be incomplete dominance or ...


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Rather than discussing what heritability is not through wordy sentences, let's just talk about what heritability is. There are two "types of heritability". Heritability in the broad sense and heritability in the narrow sense. But let's begin by defining a few other terms Phenotypic trait The phenotype is the consequence of the genotype on the world. In ...



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