What causes alleles to become dominant or recessive?

[Itoero]

Itoero,

 

I think that you are misconstruing the meaning of the word "mask." For one thing to mask something else does not necessarily mean that there has to be a direct interaction between the two things.

There is a way a dominant allele can block a recessive allele, so why wouldn't that be used in most genes? Edited October 15, 2016 by Itoero

[CharonY]

I cannot help you if you just ignore the bulk of biological required to understand the process. Not understanding proteins is not understanding what a gene is. I do not sense any effort on your side to understand the process therefore I opt to not further waste my time.

[Itoero]

I cannot help you if you just ignore the bulk of biological required to understand the process. Not understanding proteins is not understanding what a gene is. I do not sense any effort on your side to understand the process therefore I opt to not further waste my time.

Why do you refuse to answer my questions? Edited October 15, 2016 by Itoero

[CharonY]

Because you ignore my answers and questions. Asking the wrong questions won't help you understand the principles. Last try: to you understand the difference between gene and gene product?

[Itoero]

Because you ignore my answers and questions. Asking the wrong questions won't help you understand the principles. Last try: to you understand the difference between gene and gene product?

Yes I do. I asked those questions because you are imo wrong.

In your example proteins decoded by alleles of the same gene modify each other's function.

The modification of proteins is a property of genes working together, not alleles in a gene. It's called post-translational modification.

[BabcockHall]

There is a way a dominant allele can block a recessive allele, so why wouldn't that be used in most genes?

 

Asking why something would not happen in a certain way is starting out on the wrong track. The question is what does or does not happen, based on evidence.

[StringJunky]

I don't think you want to read what CharonY and I presented because you have your own pet theory... I suspect.

I wasn't wrong, was I? I think it's bad manners, dishonest and just plain annoying for someone to apparently ask a question, as though they wish to learn something, then argue that the answers are wrong as the discussion proceeds.

[Itoero]

Asking why something would not happen in a certain way is starting out on the wrong track. The question is what does or does not happen, based on evidence.

A small RNA encoded by the first allele recognises a specific sequence on the second allele and blocks its expression.

http://www.inra.fr/en/Scientists-Students/Mechanisms-of-living-organisms/All-reports/Understanding-the-mechanism-behind-dominant-and-recessive-gene-expression

I wasn't wrong, was I? I think it's bad manners, dishonest and just plain annoying for someone to apparently ask a question, as though they wish to learn something, then argue that the answers are wrong as the discussion proceeds.

I asked the cause for dominance/recessiveness and found it myself.

And explaining how alleles behave dominant does not explain what causes it.

[Delta1212]

A small RNA encoded by the first allele recognises a specific sequence on the second allele and blocks its expression.

http://www.inra.fr/en/Scientists-Students/Mechanisms-of-living-organisms/All-reports/Understanding-the-mechanism-behind-dominant-and-recessive-gene-expression

I asked the cause for dominance/recessiveness and found it myself.

And explaining how alleles behave dominant does not explain what causes it.

Except in this case, where the explanation does in fact explain exactly what causes it. You're just ignoring the explanation.

[Itoero]

Except in this case, where the explanation does in fact explain exactly what causes it. You're just ignoring the explanation.

That's not true.

Again, describing a dominant relationship does not explain what causes the relationship.

Many recessive alleles are just as functional as dominant alleles. Those recessive alleles must be blocked which is only possible if there is a chemical difference between dominant and recessive alleles, noticeable by RNA polymerase/mRNA.

A small RNA encoded by the first allele recognises a specific sequence on the second allele and blocks its expression. It's explained on this website: http://www.inra.fr/en/Scientists-Students/Mechanisms-of-living-organisms/All-reports/Understanding-the-mechanism-behind-dominant-and-recessive-gene-expression/Chapter-Three-Back-to-evolution/(key)/2

 

 

RNA polymerase binds to promotor DNA and separates the double helix.

It then adds complementary RNA nucleotides at the correct allele. This is the start of mRNA.

A ribosome translates mRNA to an amino acid chain (protein)

 

This process is the main cause for the dominant relationship between alleles.

 

When I asked for the cause, I asked why mRNA is formed at the correct allele.

It seems that RNA polymerase forms mRNA at the correct allele by the presence of sRNA or RNA targets on the allele.

[BabcockHall]

@OP,

 

E. coli is ordinarily a haploid organism; therefore, it has no need of any mechanism to make one allele silent. Yet it can be made partially diploid by using plasmids. The gene for the lactose repressor protein is sometimes given the symbol i. Most lactose repressor mutants coding for a nonfunctional repressor i^- are recessive to the wild type form i⁺. A few mutants that code for a nonfunctional repressor, however, and dominant, i^-d. How do you explain these two observations?

Edited October 17, 2016 by BabcockHall

[Itoero]

@OP,

 

E. coli is ordinarily a haploid organism; therefore, it has no need of any mechanism to make one allele silent. Yet it can be made partially diploid by using plasmids. The gene for the lactose repressor protein is sometimes given the symbol i. Most lactose repressor mutants coding for a nonfunctional repressor i^- are recessive to the wild type form i⁺. A few mutants that code for a nonfunctional repressor, however, and dominant, i^-d. How do you explain these two observations?

-A haploid organism has no need for a mechanism to mask an allele but haploid organisms use RNA polymerase, just like diploid organisms. RNA polymerase has the ability to chose between 1 or 2 alleles, regardless in which organism it's used.

-Maybe they are codominant?

[Itoero]

-A haploid organism has no need for a mechanism to mask an allele but haploid organisms use RNA polymerase, just like diploid organisms. RNA polymerase has the ability to chose between 1 or 2 alleles, regardless in which organism it's used.

-Maybe they are codominant?

Does this makes any sense?

[BabcockHall]

You are arguing against the facts, which are that most mutations in the gene for the lactose repressor are recessive, but some are dominant. I am not aware of any that are codominant.

[Itoero]

You are arguing against the facts, which are that most mutations in the gene for the lactose repressor are recessive, but some are dominant. I am not aware of any that are codominant.

ok, it just seems that a 100% dominant mutant that codes for a nonfunctional repressor is very unlikely so doesn't it make more sense that the mutant is codominant to the wildtype? Edited October 21, 2016 by Itoero