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co dominant
- Thread starter hediki
- Start date
Joejr14
Grand Bubble Burster
A codominant trait, bloodred for example, means that when you mate a bloodred with a normal (wild-type) you will not experience the typical recessive results---being all normals.
You will however something of a blended effect on the offspring. They're most commonly referred to as 'outcrosssed' bloodreds instead of het bloodreds. Since the bloodred trait is codominant to the wild type you see a mixing effect with the F1 offspring. F1 outcrossed bloods paired back together will give you regular bloodreds, normals, and more 'outcrossed' bloodreds.
Ultra and amel is another example. Both of these traits are RECESSIVE to the wild-type, but are codominant to each other due to them having the same locus. Ultra x amel = 100% ultramels, a middle point between ultra and amels.
I was trying to explain this to the boa crowd last week. If you were to pair a bloodred up with a normal and got 100% bloodreds, then bloodred would be dominant to the wild type. The resulting animals would only be het for bloodred, but it would still be displaying the bloodred phenotype.
Since you get a blended look, bloodred is codominant.
You essentially determine if a gene is codominant by breeding trials. However, thankfully, there are only a few codominant genes in the cornsnake world, and none are dominant to the wild type.
You will however something of a blended effect on the offspring. They're most commonly referred to as 'outcrosssed' bloodreds instead of het bloodreds. Since the bloodred trait is codominant to the wild type you see a mixing effect with the F1 offspring. F1 outcrossed bloods paired back together will give you regular bloodreds, normals, and more 'outcrossed' bloodreds.
Ultra and amel is another example. Both of these traits are RECESSIVE to the wild-type, but are codominant to each other due to them having the same locus. Ultra x amel = 100% ultramels, a middle point between ultra and amels.
I was trying to explain this to the boa crowd last week. If you were to pair a bloodred up with a normal and got 100% bloodreds, then bloodred would be dominant to the wild type. The resulting animals would only be het for bloodred, but it would still be displaying the bloodred phenotype.
Since you get a blended look, bloodred is codominant.
You essentially determine if a gene is codominant by breeding trials. However, thankfully, there are only a few codominant genes in the cornsnake world, and none are dominant to the wild type.
Menhir
Charmelippe
The point is, with co dominant traits, both genes show up in the phenotype.
Amel and Ultra could also be Allels and NOT co dominant, so either Amel or Ultra would completely show up in the F2 when breeding Amel x Ultra and hiding the other.
With co dominant traits, you get an "undefined" mix up of both genes.
Co dominant itself just says something about how two different allels act together. The way they can act is dominant-recessive.
Amel and Ultra could also be Allels and NOT co dominant, so either Amel or Ultra would completely show up in the F2 when breeding Amel x Ultra and hiding the other.
With co dominant traits, you get an "undefined" mix up of both genes.
Co dominant itself just says something about how two different allels act together. The way they can act is dominant-recessive.
There is no such thing as a codominant snake. It seems to me that "codominant" is being used here the way the boa pseudogenetics guys do. If so, then the corrected question asks how to determine whether a snake is homozygous or heterozygous for a given gene. Please note that heterozygous means that a gene pair contains two different genes and says nothing about what the heterozygous snake looks like. Too often people claim that a heterozygous snake looks normal. That is the definition of heterozygous for a recessive mutant gene. A snake that is heterozygous for a dominant mutant gene does not look normal but looks like a snake that is homozygous for that dominant mutant gene.hediki said:
If a mutant gene is recessive to its normal allele, then the possible heterozygote is mated to the mutant homozygote. Example: normal looking possible heterozygous amelanistic corn snake is mated to an amelanistic corn snake. If any amelanistics are among the babies, then the possible is an actual heterozygous amelanistic.
If a mutant gene is recessive to another mutant allele, then the possible heterozygote is mated to the recessive mutant homozygote. Just as the possible heterozygous amelanistic is mated to a homozygous amelanistic, except the more dominant mutant gene takes the place of the normal allele.
If a mutant gene is dominant to its normal allele, then the possible heterozygote is mated to the normal homozygote. Example: possible heterozygous salmon boa constrictor is mated to a normal boa constrictor. If any normals appear among the babies, then the salmon is a heterozygous salmon.
If a mutant gene is dominant to another mutant gene, then testing for heterozygosity is the same as when a mutant gene is recessive to another mutant gene. The possible heterozygote is mated to an individual that is homozygous for the more recessive mutant gene.
If a mutant gene is codominant to its normal allele, then ideally you can tell the identity of the genes from the way the snake looks. To be certain, mate the possible heterozygote to the normal homozygote. Example: possible heterozygous tiger reticulated python is mated to a normal reticulated python. If any normals appear among the babies, then the tiger is a heterozygous tiger.
If a mutant gene is codominant to another mutant gene, then mate the possible heterozygote to whichever homozygote that is farthest in appearance from the suspected heterozygote. For example, if ultra and amelanistic are codominant to each other, and you want to make sure that a suspected heterozygous ultra//amelanistic is actually that, then mate it to a homozygous amelanistic. If any amelanistics appear, then the parent is indeed a heterozygous ultra//amelanistic.
There are some other variations, but these crosses will do the trick. Clear as mud? For more information, look up "test cross" in a good genetics text book.
Joejr14
Grand Bubble Burster
Yah, like Tom said.
Ultramel (ua) x amel (aa) =
Ultramel gives either (u) or (a), so that paired with (a) will give you (ua) and (aa).
Since Ultramel is essentially a heterozygous pairing there are not two copies, and therefore (u) and (a) are not passed on. I think that's where you're getting confused.
If Ultramel was (uuaa) then it could be het for ultramel, but since it's only (ua) there is no such thing as het ultramel. Het ultramel is used to label things that are either het ultra, or het amel---and that is always said when using the term 'het ultramel'.
Ultramel (ua) x amel (aa) =
Ultramel gives either (u) or (a), so that paired with (a) will give you (ua) and (aa).
Since Ultramel is essentially a heterozygous pairing there are not two copies, and therefore (u) and (a) are not passed on. I think that's where you're getting confused.
If Ultramel was (uuaa) then it could be het for ultramel, but since it's only (ua) there is no such thing as het ultramel. Het ultramel is used to label things that are either het ultra, or het amel---and that is always said when using the term 'het ultramel'.
Menhir
Charmelippe
Joejr14 said:
I personally would recommend not to use "het Ultramel" cause there is also no such thing like "hom Ultramel". Correct would be het. Amelanistic or Ultramelanistic. Who is using that way of labeling?
I don't know why everyone is trying to combine co dominant with the way ultramel is "created". This is NOT explained by co dominant, at least not directly. Better would be to explain that they are allels and what does that mean - Paulh as well as Joe did that indirectly I think. Then explain that allels can influence each other in different ways when they are combined heterozygously with another Allel (dominant-recessive or co dominant).
In my experience, this is what people do understand better.
Het amel means an amelanistic mutant gene paired with its normal allele.
Het ultra means an ultra mutant gene paired with its normal allele.
There is no het ultramel because there is no ultramel mutant gene. But het ultra//amel and ultra//amel and a<sup>u</sup>//a<sup>a</sup> are acceptable. So is just ultramel. Het means that there are two different alleles present. "//" means a pair of chromosomes, with ultra on one chromosome and amelanistic on the other.
Het ultra means an ultra mutant gene paired with its normal allele.
There is no het ultramel because there is no ultramel mutant gene. But het ultra//amel and ultra//amel and a<sup>u</sup>//a<sup>a</sup> are acceptable. So is just ultramel. Het means that there are two different alleles present. "//" means a pair of chromosomes, with ultra on one chromosome and amelanistic on the other.
Jynx
Digger, RN
I can see how this can be confusing to someone. Perhaps it would be best to explain that an ultramel is technically a het animal because there are two unidentical genes at work, which is what the "technical" definition of heterozygous means vs homozygous which has two identicle genes at work.
Oi...you boys are going to confuse everyone. lol
PaulH is a little better to understand.
Oi...you boys are going to confuse everyone. lol
PaulH is a little better to understand.
TBurkeIII
TBurkeIII
:roflmao: thats funny jinx i noticed that too!
i dont think there is any easy way to go about it in my opinion. there are so many ways for this to be confused. if we were all working from the same text as if we were in a classroom it would be easier to compare so we have the same basis for comparison. unfortunately, being that we all understand things in our own way there will have to be some independent thought on the part of the person trying to understand it. dont get to engrossed into what others are saying but, take what you can from what they are saying and process it anyway you can. from there help can be added along the way.
i dont think there is any easy way to go about it in my opinion. there are so many ways for this to be confused. if we were all working from the same text as if we were in a classroom it would be easier to compare so we have the same basis for comparison. unfortunately, being that we all understand things in our own way there will have to be some independent thought on the part of the person trying to understand it. dont get to engrossed into what others are saying but, take what you can from what they are saying and process it anyway you can. from there help can be added along the way.