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14 votes

Can a blood type O be born from AB and A parents?

The ABO blood type is controlled by a single gene (the ABO gene) with three types of alleles inferred from classical genetics: i, IA, and IB. The IA allele gives type A, IB gives type B, and i gives ...
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12 votes
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Are alleles equally sized?

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 ...
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11 votes
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Do some genes follow Rock-Paper-Scissors model of dominance?

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 ...
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6 votes

What are multiallelic genes?

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 ...
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6 votes

How does the molecular machinery choose where to cut a chromosome for recombination?

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 ...
6 votes
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What is meant by 'identical alleles'?

These are just issues with singular and plural and whether you refer to individual copies or categories/types. Two of the same allele copies are the same allele (category/type). Two different alleles (...
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5 votes
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How allele is related to trait that is more complex than two cases (ex. height)?

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,...
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5 votes

Genetic mutations and new alleles

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 ...
5 votes
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Microsatellite shifts (peak calling) GeneMapper! Thesis help!

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 ...
5 votes
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How does the molecular machinery choose where to cut a chromosome for recombination?

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 ...
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5 votes

How does sexual reproduction generate more genetic variation?

Short answer it doesn't. Sexual reproduction generates new combinations of traits and increases the difference between individuals in the same populations. New combinations means beneficial traits ...
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5 votes
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Question regarding the number of alleles

The two-allele scenario is often used in genetics teaching because of its simplicity. However, quite a few genes have more than two alleles. Some examples that readily come to mind are: The ABO gene ...
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5 votes
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Red and White Flower or purely Pink? Phenotype of a Flower Species with a Co-dominant Trait

Unfortunately, that nomenclature is kind of old-fashioned; it predates our understanding of what's going on at a molecular level. Don't get hung up on the language. Lots and lots of genes and ...
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4 votes
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Is the term 'allele' specific to sexual populations?

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 ...
4 votes

How does sexual reproduction generate more genetic variation?

There are two questions here. 1) What is genetic variance? It is actually clearly defined. 2) How does sexual reproduction generate more genetic variation? What is genetic variance? Assuming bi-...
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3 votes

What is a gene transcript, how is it different from an allele?

No. A gene is a unit of the genome stored in the form of DNA. It can be transcribed into mRNA (the transcript) to be used as a template in protein synthesis. A gene can come in many different ...
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3 votes
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Albinism inheritance problem: what are the father's alleles if he got an albino kid?

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 ...
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3 votes
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Mitotic crossover happens in G1?

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 ...
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3 votes
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Dominance coefficient

Thank you for asking such a well-thought out question, I really enjoyed how hard this made me think about the concept. I think there might be an issue here that's quite common to biology, in my ...
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3 votes

how can a recessive allele become represented in a significant number of individuals in a population

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 ...
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3 votes
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Is protein production doubled if you have homozygous dominant genes as opposed to heterozygous genes?

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 ...
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3 votes

How does allele dominance work in polyploid organisms?

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 ...
3 votes

What is an allele?

The question takes one sentence in the Nature Scitable article about alleles out of context. The statement: “Humans are called diploid organisms because they have two alleles one from each parent....
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3 votes
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Get "DNA" of one parent based on its children

Ok, I think I can answer somewhat usefully with the update. It's helpful in this case to think in terms of sampling alleles. It's true that the cases that you give are not 100% unambiguous, but it is ...
2 votes
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Why do almost all SNPs have two alleles?

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 ...
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2 votes
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Recessiveness of allele for protection of organism

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-...
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2 votes

Recessive alleles at Hardy-Weinberg equilibrium

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 ...
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2 votes

Calculating pairwise Fst from allele frequencies

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 ...
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2 votes

Genetic mutations and new alleles

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 ...
2 votes
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Relationship between genetic diversity within and between species

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 ...
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