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12

In general, alleles don't have to be the same size. Two major examples which come to mind are the Huntingtin gene and FMR1. Huntingtin is the causative gene of Huntington's disease. In people with Huntington's, a sequence of three nucleotides is repeated. The number of repeats varies, from a low of 9 in unaffected individuals, to more than 60 in severely ...


11

A quick search gives this same question in this Reddit post. Apparently, there is not yet an existing example of such dominance of three alleles on one another. That said, if you're interested in rock-paper-scissor patterns in nature, then you will be interested in the side-blotched lizard. It has three genetically encoded male "sexes", that also ...


9

SNP Let's start with the definition that has nothing to do with the rest of the question :). A Single-Nucleotide-Polymorphism (SNP) is a kind of genetic variation that you find in population. This genetic variation is defined as a variation caused by only one single nucleotide (as its name indicates it). For example if you have in the populations the two ...


7

Homologous Recombination not only shuffles different mutations together, but similar sequences near each other from gene duplication events and from regions with highly repetitive sequences can recombine and cause gross changes in the sequence of the genome in hot spots.


6

In humans and mice anyway ,a lot of it boils down to the recognition of a specific sequence that marks recombination hotspots by PRDM9. http://www.sciencemag.org/content/327/5967/836 Edit - I'm expanding in response to the comment below... Meiotic recombination occurs at vastly greater frequencies in some locations in the genome than others and these are ...


6

More than two alternative forms (alleles)of a gene in a population occupying the same locus on a chromosome or its homologue is known as multiple alleles. Multiple alleles arise due to mutations of gene.A gene can mutate several times by producing a series of alternative expressions.Different alleles in a series show dominant-recessive relation or may show ...


5

Your markers are probably fine, especially because you keep seeing the same allele in multiple individuals. Dinucleotide repeats do not always copy perfectly. More likely, remember that the primers you use to amplify your microsatellites bind outside of the actual repeat region. You could have an insertion/deletion in the region between the primers and the ...


5

The question is very broad and complicated, since the situation may differ in prokaryotes and eukaryotes. Nevertheless, I'm citing a good paper that is closely related to your question: Studies in yeast show that initiation of recombination, which occurs by the formation of DNA double-strand breaks, determines the distribution of gene conversion and ...


5

So the term allele is a broad one, and simply refers to the different versions of any piece of DNA in circulation in the gene pool - it doesn't need to refer to a gene. I can talk about the alleles at a random place in the genome. But if we proceed with your question and ask - 'do nonsense mutations within coding genes also lead to the creation of different ...


5

You are absolutely correct that many traits are not "digital", but "analog". In genetics, these are usually called quantitative traits. Such traits generally do not follow Mendel's laws of inheritance, but are said to have "complex inheritance". Most traits (phenotypes) in biology at the level of whole organisms probably have complex genetics; height is a ...


4

No, it's fine to use for asexuals too. There's an ambiguity in the term "locus" for asexuals, but "allele" is fine, and "gene" is not much more ambiguous than it is for sexuals (which isn't saying much). Your final paragraph seems confused though, and I think it's related to your main question. When recombination is sufficiently frequent to keep the ...


3

Super oober short answer: The father is Cc, the mother is cc, there is a 50% chance the children will be albino (as you predicted). An explination on Mendelian genetics: First let's look at (what a lot of people consider) the normal Mendel table from here: Since the dad is normal, that means he has at least one Normal Gene. Which makes him C ? . We also ...


3

An allele is not dominant or recessive by itself. It is dominant or recessive compared to another allele. Therefore, if you consider one locus (position on a sequence) that has two alleles (bi-allelic locus), you cannot have two dominant or two recessive alleles. It is like saying that two things are darker. In reality you can either say that one is darker ...


3

The short answer is: Because of genetic drift. If a mutation does not influence the fitness in heterozygote individuals, then its frequency varies only through genetic drift while it reaches some high enough frequency. If by chance, the frequency of this new allele achieve a high enough level so that the homozygous for this allele given by $x^2$ where $x$ is ...


3

An interesting question! During homologous recombinations many mutations are actually fixed (here meaning that those that have accumulated over time can be restored) as both chromosomes are condensed and can be compared by the DNA repair enzymes. However additionally mutations can occur and be passed on. As gametocytes primarily do not have to do much more ...


3

Many mutations occur during DNA replication (or when a mutagen is around, but that also largely affects replication). Mutations occurring "during sexual reproduction" might occur during gametogenesis, when the eggs and sperm are developing in the parents. If a mutation were to occur during these processes, it could be that the alleles in the offspring are ...


3

First off this is called genetic mosaicism and indeed mitotic recombination is a contribution factor. Mitotic crossover events involve the exchange, by homologous recombination, of regions of chromosomes. 60% of homologous recombination events might occur during G1 and 40% of those event occurs after chromosomes are replicated (see this paper). For twin ...


3

A recessive allele is one whose phenotype can be masked by a dominant allele. A recessive allele is not necessarily deleterious, and the dominant allele does not necessarily have higher fitness than the recessive allele. Fitness and dominance are often confused, but they are not the same thing. In some scenarios, the recessive allele indeed confers a ...


3

Dominance is defined based on the phenotype Dominance is defined based on a phenotype of interest. Pick a phenotype, say coat color for example. If genotypes AA and Aa have the same coat color while aa has another coat color, then A is domiant over a. The concept hold even for sequence that do not produce proteins The concept of dominance can be applied ...


3

Dominance works in the same way. However, polyploids have complex inheritance patterns! 1. Punnett square for polyploid inheritance One might assume that you would need a four-dimensional table for tetraploids, a six-dimensional table for hexaploids, and an eight-dimensional table for octoploids. The table you mentioned in this case should be the ...


2

Until now, it looks good. When you are looking at basic mendelian gene linkage problems like these and you find out that the chi square analysis rejects your hypothesis, it means that there is linkage. In that case, you should have a case where your two recombinant genotypes have an approximately equal number of progeny and your two parental genotypes also ...


2

Question a The only possible genotype that brings a phenotype of 12 inches is: $AABBCC$. Similarly the only possible genotype that bring a phenotype of 6 inches is: $aabbcc$. In consequence the offsprings can only be: $AaBbCc$ which measure $2+1+2+1+2+1 = 9$ inches. Question b Now the question is: if we breed two $AaBbCc$ how many offsprings measure 11 ...


2

Instead of dividing mutations into two classes, dominant vs. recessive, consider categorizing them into classes based on how the mutation affects the gene--or the gene product. This yields loss-of-function (lf) alleles, that reduce the activity of the gene, or its product, and gain-of-function (gf) alleles that act as if they somehow increase the activity ...


2

Let's go through the possible answers. Which of the following could be predicted? Not (1), because we don't know whether selection favors or disfavors the recessive alleles. Not (2) for the same reason. Not (4) by definition. Not (5) because recessive alleles don't magically become dominant. This leaves us with (3), which also seems correct: not only do we ...


2

The original Wright's formulation $$Fst=\frac{var(p)}{\bar p}$$ , where $\bar p = \frac{1}{J} \sum_{j=1}^J p_{j}$ and $var(p) = \frac{1}{J}\sum_{j=0}^J (p-\bar p)^2$ is the variance in frequencies among populations. This original formulation is valid only for a bi-allelic locus. Nei (1973) generalizes this definition to loci that have more than two ...


2

Well, though it is possible to have SNPs of more than two alleles, and some exist, due to the low probability of having a basepair change twice in the same base-pair (there are aproximately 3.000 Mb in the human genome) and have it in more than 1% of the population (remember we are talking about single nucleotide polymorphism) to classify as a polymorphism ...


2

Allele is just a variant form of gene: independent of the final product of protein, so nonsense will also lead to new allele. I will quote Nature Scitable here: Alleles can also refer to minor DNA sequence variations between alleles that do not necessarily influence the gene's phenotype.


2

Metrics of interest The two metrics you are interested in are $\pi$ - the mean number of differences between two randomly sampled (with replacement) alleles in a population $d$ - the mean number of differences between two randomly sampled (with replacement) alleles coming from two different species Consider two sequences ATCGTCAAT ATAGTTAAT There are 2 ...


2

The comments are very unclear and your interpretation of the figure seems very wrong (no offense). You should have a look at an intro course (such as this one by Khan Academy) as asking such intro questions here will require for one to rewrite an entire course. The pink and blue thingies on the image are chromosomes, not gametes. A gamete is a haploid cell (...


2

I thought a transcript was the RNA sequence produced from transcription. The RNA copy of an allele that gets spliced and translocated to the cytoplasm for translation. Not sure if Wikipedia references are allowed here, but they seem to agree with my understanding. An allele is a specific copy of a gene, i.e. you have two copies (alleles) of gene X; allele ...


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