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Questions tagged [allele]

Alleles are different forms (among many possible alternative forms) of the same gene.

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In the context of GWAS we have an alternate allele and a reference allele. Why do we only have one possible alternate instead of three?

I recently started analyzing a GWAS summary dataset. It has a column for the reference allele in which it mentions the base in the reference genome. There is another column for the alternate allele (...
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Have there ever been "half-twins" who were halfway between siblings and twins?

Have there ever been two human siblings who were 75% or more genetically related?
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Gene Mapping - Please explain in Lay terms

Taking an AP bio course, and for some reason I cannot comprehend the mechanism of how one determines the location of alleles on a chromosome. The math is simple and I can memorize it, but its bugging ...
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Can a deletion occur on only one strand of a human chromosome?

Hello. Is it possible that a deletion can occur in the middle of only one strand of a human autosomal chromosome?
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Considering Two Genes, Are There Only Two Possible Outcomes for the Four Gametes Produced After Meiosis, Regardless of Independent Assortment?

Is it true that for a single meiotic event when considering only two genes, there are only two possible genetic outcomes among the four gametes produced, regardless of whether the two genes are found ...
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Trying to find information about intraspecific allelic expression divergence in recombinant individuals due to changes in the cis regulatory regions

I am trying to find any research articles or resources that focus on differences in expression levels at the allelic level due to changes in cis regulatory regions in recombinant individuals. For ...
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What really is an allele?

My textbook says: genes which code for a pair of contrasting traits are known as alleles. Then that means T and t are alleles. Further, it says: Mendel also proposed that in a true breeding, tall ...
Charles's user avatar
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Inferring mother's allele probability based on father and children

I am currently in the process of analyzing our family's genome. I do have access to his, mine and our father's genome, but not to our mother's (deceased). I was wondering how I could combine our 3 ...
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Genotype vs Alleles - What's the difference?

I have searched through various websites, however, I am still rather confused with the difference between 'genotype' and 'alleles' since each site seems to be contradicting another site. I would be ...
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Can gene mutations cause Down's syndrome in humans?

I am working on an A levels questions: Which of the following statements about gene mutation is incorrect? A. It can occur in both somatic and sex cells B. It can cause Down's syndrome in humans C. ...
green onion's user avatar
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What is meant by 'identical alleles'?

I read in my book that "two alleles are considered to be homozygous if they are identical". But at the same time I read the definition of allele to be: genes which code for a pair of ...
loadingbar's user avatar
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Expected variant allele frequency of mutation present on 2 out of 3 copies of a 70% purity cancer sample

I am reading Nik-Zainal et al., 2012. In such paper, (for sample PD4120a - a 188-fold depth ER+ breast cancer tumor), it is stated that: The sample has 70% tumor purity. The genome has one triploid ...
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What is the heredity model of the following heredity tree?

I have the following heredity tree: and I need to decide which heredity model it fits the most, with the least number of assumptions, from the following models: autosome dominant autosome recessive ...
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How can a minor allele frequency be >50% (reported in GNOMAD)?

I'm receiving a data set to start an analysis. My collaborators ran GATK to find variants from sequencing data, and GNOMAD calculated the minor allele frequencies - and then I'm receiving this MAF ...
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Could someone explain how chromosomes are counted here?

I'm not sure how chromosomes are counted in this picture. I would reason that there would be 8 chromosomes in the diploid cell, but that doesn't seem to be the case. Could someone explain?
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How is it determined whether a chromosome is maternal or paternal for imprinting?

For imprinting, how does the cell determine which chromosome is maternal and which is paternal? For example, in the parental imprinting of insulin-like growth factor 2 (Igf2) on chr7 (autosome), how ...
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Is it possible for a brown cat to birth an orange kitten?

I have a brown (cinnamon) cat, I assume her alleles would be b’b’ and oo. She was bred with either a black male (B_ o) or an orange male (__ O), or both if it’s possible for her to have carried the ...
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Red and White Flower or purely Pink? Phenotype of a Flower Species with a Co-dominant Trait

As I understand it, co-dominance is when both genes in an allelomorphic pair produce both their effects equally on the organism in question whilst incomplete dominance applies to an instance where a ...
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Can a blood type O be born from AB and A parents?

I have a basic understanding of genetics, and I'm really puzzled by this. My grandma's blood type is A (I don't know if it's heterozygous or homozygous) and my grandpa is AB. Yet my mother is type O. ...
Pate Ardealul's user avatar
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Get "DNA" of one parent based on its children [closed]

I'm no biology expert so bear with me, but I've been given a task to estimate alleles of an animal based on the animal's children and the children's other parents. I've looked up Mendel's laws but I'm ...
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Expected number of mismatches between two alleles of a gene in a population?

I can't find any article about the expected number of mismatches in alignment of two alleles of an assumed gene. Any reference or information about allele mismatch ratio (in a species or higher taxa) ...
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Hardy-Weinberg principle

The following paragraph on Wikipedia about the Hardy-Weinberg principle is bothering me. It should be mentioned that the genotype frequencies after the first generation need not equal the genotype ...
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Do we come to know which allele is dominant by seeing family genration tree only?

I know that a Gene has Alleles (variation) and one is Dominant over Other i.e the Other Recessive. Then I got a Thought that How can we tell whether an Allele is Dominant or Recessive...... and I came ...
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Can alleles have cyclic dominance?

Do the relationships between alleles always form a hierarchy? Ignoring partial and codominance, can alleles have a cyclic relationship? For example, is there anything that exists analogous to the ...
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Alleles and Ploidy [closed]

I was recently studying inheritance and variation and came across a sentence: A diploid organism can show only two alleles How is this possible?
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Are probabilities of mutations symmetric?

For the premise of this quiestion let's assume that there is an allele A and an allele B. The allele A has a probability P to mutate into the allele B in the given timeframe. Is it also true that the ...
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Question regarding the number of alleles

Why is it that in biology we often say that a gene has two alleles? When we analyze allele frequencies (e.g. using Hardy-Weinberg Equilibrium), formulas are often generalized for two alleles of a gene....
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ABO allele frequencies: Why use the EM algorithm?

In textbooks and lecture notes and slides posted online, determining allele frequencies using blood type information (ABO), under the assumption of Hardy-Weinberg equilibrium, is accomplished using ...
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Will a less favorable allele's frequency go to 0?

For example, a pond is dark in color. There are two alleles. The dark color allele is dominant over the light color one. Let's assume that the relative fitness of both the homozygous dominant and ...
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What is an allele?

According to the entry for allele in Wikipedia: “An allele is a variant form of a given gene, meaning it is one of two or more versions of a known mutation at the same place on a chromosome.” ...
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Do some genes follow Rock-Paper-Scissors model of dominance?

Assuming there are at least 3 alleles of the gene $G$ in total - $G_R$, $G_S$ and $G_P$ - is there any gene for which the following is true? $G_R$ is more dominant than $G_S$. $G_S$ is more dominant ...
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Easy Hardy Weinberg Equilibrium [duplicate]

Hi My friend and I get 2 different answers to this question. I would like to know how to calculate the value of q. My friend says that 500/1500=q because there are 500 recessive alleles in the ...
alex's user avatar
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How to determine if two mutations in a gene are on the same or different alleles?

I would like to know, except a familial study, is there another way to determine if a mutation/variation is cis or trans (i.e. on the same or different alleles)? For example by sequencing technique or ...
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is it possible for a son to inherit an allele on a Y chromosome?

Obviously, the only way for one to be male is to inherit the Y chromosome, but are there alleles on the y chromosomes? Or is it just automatically the recessive trait without an allele.
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What is the cause of "imbalanced" linkage disequilibrium?

With perfect linkage disequilibrium ($D' = 1, R^2 = 1$), you might have the following table of counts for the alleles: B b A 100 0 a 0 100 With "...
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My understanding of chromosomes and the processes related to them is lacking [closed]

I'm sorry for the incredibly simple question, I just can't seem to find any answers elsewhere online. I am a high school student currently studying for the upcoming AP biology exam, and recently I ...
scripturient's user avatar
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2 answers
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Are there only a few alleles or groups of many alleles impacting protein structure and function?

I'm in the first year of Medicine and I'm studying Genetics and Evolution. I have this doubt in the back of my mind and I'm not being able to move forward without someone explaining me what's wrong ...
João Maldonado's user avatar
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Does the law of independent assortment apply to homologous chromosomes or alleles, or both?

My textbook is giving me two definitions 1st def: "random orientation of homologous chromosomes at the metaphase plate in meiosis 1." 2nd def: "alleles for one gene separate into gametes ...
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How can inbreeding be used for selecting mutations?

I understand that inbreeding, after a number of generations of crossing genetically related individuals eventually yields homozygotes, however I can't seem to understand how it can be used for ...
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GEN file format, SNPs and alleles

I have a few questions I can't seem to get a straight answer to, regarding the .gen file format and also biology in general. The ...
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1 answer
228 views

Is there a practical upper limit to ploidy?

In my AP Biology class, we were discussing polyploidy, specifically, its deleterious nature in mammals and its prevalence in plants. We also learned that commercial crops, especially fruit, are often ...
Gnumbertester's user avatar
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For allele frequency determination, is it good to take samples from a college/school or a hospital or any other technique?

I am trying to determine allele frequency of a hla allele. Preliminary analysis shows the prevalence of the allele (homo or heterozygous both) is 3%. The allele is related to a disease (After exposure ...
Mr. Divya's user avatar
1 vote
0 answers
35 views

Is bi-allelic gene expression random?

Supposing we have the genotypes “Aa”, “AA”, and “aa”... which are not mono-allelic (not imprinted and not X-inactivated). Does the dominance of the “A” allele over “a” allele affect which gene is ...
P...'s user avatar
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Finding specific genotype occurrences given allele frequency

So let's say I have a tetraploid species and I have 4 possible alleles for a particular locus. I have found that I can have 35 total possible genotypes and I know the allele frequencies for each of ...
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Gene expression: which allele is considered?

For human beings, we have two copies of each gene inherited from the parents. The question is, when referring to gene expression, which copy (or allele) is considered?
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why and how multi allele gets reported during variant calling in vcf?

This might be a very basic question for many here. With the basic understanding of inheritance, eventhough there is a possibility of multiple genotypes due to multi alleles, the resulting genotype can ...
Gopinath S's user avatar
1 vote
1 answer
2k views

Genotypes of gametes produced by an F1 individual?

I have an urgent question as I have an exam tomorrow. I was skimming some past exam papers and one question came up which has me completely confused. A cross was made between a pure breeding diploid ...
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1 answer
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Impact of Natural Selection on Population Size [closed]

I have conducted a lab with my IB Biology 11 class, regarding changes in allele frequencies within generations overseeing the natural selection of an advantageous phenotype. We were looking to ...
Johnny Toff's user avatar
-1 votes
1 answer
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Simple Autosomal Recessive question by a novice genetics student

How do you figure the percentage of offspring that will be a carrier of an Autosomal Recessive gene when the FATHER is the recessive carrier and the MOTHER is not affected (normal, no recessive)? ...
Tristan's user avatar
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Are mutations the cause of alleles?

For example, some leopards have a mutation which causes black fur. So Black fur and normal fur colour (orange-white) are both alternate forms of the same gene, right? So does that mean that mutations ...
Christopher U's user avatar