# two dominant genes



## bob_l (Apr 14, 2007)

I've just started reading up on my genetics and its mostly ok, but a couple of things i havent found are:
-what is talbino?
-what happens when two different dominant (or recessive) alleles are present?
-how do co-dominant genes work?

thanks
rob


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## Ssthisto (Aug 31, 2006)

"Talbino" is an abbreviation for "Tremper Albino" - one of the three albino-effect genes in leopard geckos.

Now, T+ and T- albino are different - they refer to the chemical mechanism that causes the albino appearance.

Dominant and recessive alleles - it depends on whether you're talking about *different* loci or *the same* locus. If they're two different loci, you get "combination" morphs - like Blazing Blizzard in leopard geckos or Amber in corn snakes or Albino Genetic Stripe in royal pythons. If they're the same locus, it depends on how the two alleles relate to each other (instead of to "wildtype") - for example, Motley and Stripe in corn snakes exist at the same gene locus. Motley, however, is dominant to Stripe - if you cross a Motley to a Stripe you get all Motleys-het-for-Stripe.

As for Codominant genes, that's a difficult one to explain - what do you want to know about how they work?


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## bob_l (Apr 14, 2007)

i'd like to know what the phenotype of a co-dominant is when combined with a dominant, recessive or another co-dominant gene.

if heterozygous of one dominant gene is bred with a heterozygous of another dominant gene, what are the results? is the phenotype 50:50? 

rob


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## gazz (Dec 9, 2006)

bob_l said:


> what is talbino?.


Talbino = Tremper albino.As there are 3 strains of albino in leo's.Balbino = Bell albino and Ralbino = Rainwater albino.And there NOT compatible with each other.



bob said:


> -what happens when two different dominant (or recessive) alleles are present?


They combind.
--------------
(DOMINANT)-Result vary on wheather the leo has 1 copy or two copys on the dominant gene.

[1C]Hypo X [1C]Enigma = .

Normal.
[1C]Hypo.
[1C]Enigma.
[1CH,1CE]Hypo enigma. 
----
[2C]Hypo X [1C]Enigma = .

[1C]Hypo.
[1CH,1CE]Hypo enigma. 
----
[1C]Hypo X [2C]Enigma = .

[1C]Enigma.
[1CH,1CE]Hypo enigma. 
----
[2C]Hypo X [2C]Enigma = .

[2CH,2CE]Hypo enigma.
----
===
(RECESSIVE)-First generation you get normal double HET.
So.

Talbino X Blizzard = .

Normal HET Talbino,Blizzard.
----
Normal HET Talbino,Blizzard X Normal HET Talbino,Blizzard = .

Normal Poss-HET Talbino,Blizzard.
Talbino Poss-HET Blizzard.
Blizzard Poss-HET Talbino.
Talbino blizzard(resulting combo).
===
----



bob said:


> -how do co-dominant genes work?


Codominant works the same as recessive BUT not only does the Homozygous leo look visually differant to a normal leo.The Heterozygous leo also looks visually differant to a normal leo.

Snow is (Heterozygous).
Super snow is (Homozygous).

Normal X Snow = 50%Normal/50%Snow.

Snow X Snow = 25%Normal/50%Snow/25%Super snow.

Snow X Super snow = 50%Snow/50%Super snow.

Super snow X Super snow = 100%Super snow.


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## Ssthisto (Aug 31, 2006)

Ok, here's a for-real example:

Spider in royal pythons is dominant to wildtype.
Pinstripe is also dominant to wildtype, on a different gene locus to Spider.

Breed a heterozygous-Spider to a heterozygous-Pinstripe, you have a:

25% chance per egg of normal offspring not carrying either trait.
25% chance per egg of Pinstripe offspring not carrying Spider
25% chance per egg of Spider offspring not carrying Pinstripe
25% chance per egg of Spinner (spider pinstripe) offspring.

Conversely, Butter is codominant to wildtype.
Pinstripe is still dominant to wildtype on a different gene locus.

You have the same spread of ratios - 25/25/25/25 - but the combination is Butter Pinstripe rather than Spinner.

But breed a heterozygous Pinstripe to, say, a homozygous (recessive-to-wildtype) Albino, you'll get:

50% chance per egg of normal het albino
50% chance per egg of Pinstripe het albino


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## bob_l (Apr 14, 2007)

that makes sense
thanks guys
rob


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## gazz (Dec 9, 2006)

bob_l said:


> i'd like to know what the phenotype of a co-dominant is when combined with a dominant, recessive or another co-dominant gene.


Examples.

Codom snow HET.
------------
Snow X [1C]Hypo = .

Normal.
Snow.
[1C]Hypo.
[1C]Hypo snow.
----
Snow X [2C]Hypo = .

[1C]Hypo.
[1C]Hypo snow.
----
===
Super snow X [1C]Hypo = .

Snow.
[1C]Hypo snow.
----
Super snow X [2C]Hypo = .

[1C]Hypo snow.
----
===
Codom snow
------------
Snow X Talbino = 

Normal HET Talbino.
Snow HET Talbino.
----
Snow HET Talbino X Snow HET Talbino = .

Normal Poss-HET Talbino.
Talbino.
Snow Poss-HET Talbino.
Talbino snow.
Super snow Poss-HET Talbino.
Talbino super snow.
----
===
Codom snow & Codom Giant.
----------------------------
Snow X Giant = .

Normal.
Snow.
Giant.
Giant snow.
----
Super snow X giant = .

Snow.
Giant giant.
----
Snow X Super giant = .

Giant.
Giant snow.
----
Super snow X Super giant = .

Giant snow.
----
Giant snow X Giant snow = .

Normal.
Giant.
Super giant.
Snow.
Giant snow.
Super giant snow.
Super snow.
Giant super snow.
Super giant super snow.
----
Super giant super snow X Super giant super snow = .

Super giant super snow.

This info any use to ya!.


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## gazz (Dec 9, 2006)

bob_l said:


> i'd like to know what the phenotype of a co-dominant is when combined with a dominant


There is however a spanner in the works.

There are two strain of genetic snow.Codominant-AKA-Mack and Dominant-AKA-TUG/GEM.And thay combo to produce a Homozygous version super snow.

Dominant snow.
---------------
[1C]Snow X [1C]Snow = .

Normal.
[1C]Snow.
[2C]Snow.
----
[2C]Snow X [1C]Snow = .

[1C]Snow.
[2C]Snow.
----
[2C]Snow X [2C]Snow = .

[2C]Snow.
----
===
Codominant snow.
------------------
Snow X Snow = .

Normal.
Snow.
Super snow.
----
===
Codominant snow & Dominant snow.
-----------------------------------
Codom Snow X Dom Snow = 

Normal.
Snow.
Super snow.

No ones really sure how.Or if the resulting snows are Codom snows or Dom snows or bit of both.Hopfully the future will tell.


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## bob_l (Apr 14, 2007)

thats cleared up alot. thanks
i'd previously been looking at the predicted breeding results on other threads wondering how people were coming up with any of it, but now i work through it and draw it out, it finally makes sense!
thanks alot, very helpful


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## paulh (Sep 19, 2007)

gazz said:


> Codominant works the same as recessive BUT not only does the Homozygous leo look visually differant to a normal leo.The Heterozygous leo also looks visually differant to a normal leo.


Codominant does *not* work the same as recessive. Because, as gazz states, a leo that has a codominant mutant gene paired with a normal gene does not look like a normal leo.

Codominant mutant genes are great! Because you can tell what the genes are just by looking at the animal. There is none of the 66% or 50% probability het for the mutant gene as there is with dominant and recessive mutants.

Here are the possible effects of a mutant in one gene pair combined with a mutant in a second gene pair:

(1) The effect of one mutant may completely hide the effect of another mutant gene. Example: in mice, the nonagouti mutant gene is a recessive that turns the mouse solid black. The albino mutant gene turns a mouse white with pink eyes. A mouse with two albino mutant genes and two nonagouti mutant genes is white with pink eyes. Sombre is a dominant gene in the mouse, but an albino sombre mouse is also white with pick eyes.

OR 

(2) the effects of the two mutants may be separate. Example: In mice, the pintail mutant gene is a dominant that makes the tail about half as long as a normal tail. A pintail albino mouse has a short tail and is white with pink eyes.

OR 

(3) the effects of the two mutants may combine. As in the spinner ball python, which is both spider and pinstripe.

The mutant in the first gene pair could be dominant, recessive or codominant to the normal version of the gene. It makes no difference. The mutant in the second gene pair could be dominant, recessive or codominant to the normal version of the gene. Again, it makes no difference. Given my choice of mutants in a species with a lot of mutants, such as the lab mouse, I could figure out combinations that would produce any of the three effects above. Reptiles do not have enough mutants for that yet. But maybe in 50 or 100 years they will.


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## paulh (Sep 19, 2007)

If you can do a Punnett square for one gene pair, you can do it for two gene pairs. Make a Punnett square for both gene pairs individually. Then take the second Punnett square and put it in each box of the first Punnett square.

Ssthisto's het spider X het pinstripe mating has two gene pairs. Individually, the gene pairs work out to het spider X normal and het pinstripe X normal.

het spider X normal -->
1/2 het spider
1/2 normal

het pinstripe X normal -->
1/2 het pinstripe
1/2 normal

Put the second gene pair's Punnett square in each box of the first gene pair's Punnett square:

1/2 het spider 1/2 het pinstripe
1/2 het spider 1/2 normal
1/2 normal 1/2 het pinstripe
1/2 normal 1/2 normal

and the final result is
1/4 het spider het pinstripe (spinner)
1/4 het spider (spider)
1/4 het pinstripe (pinstripe)
1/4 normal

just as in Ssthisto's post.

Now you may think I cheated a bit using Punnett squares that are two boxes high and one box wide, but it works the same with Punnett squares that are two boxes high and wide. In such a case, the second gene pair's 4 box Punnett square goes into the first gene pair's top left box, again in the top right box, again in the bottom left box, and again in the bottom right box.


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## gazz (Dec 9, 2006)

paulh said:


> Codominant does *not* work the same as recessive. Because, as gazz states, a leo that has a codominant mutant gene paired with a normal gene does not look like a normal leo.
> 
> Codominant mutant genes are great! Because you can tell what the genes are just by looking at the animal. There is none of the 66% or 50% probability het for the mutant gene as there is with dominant and recessive mutants.


I maybe could have worded it better.I was getting at there is a Heterozygous a Homozygous in a sence same as recessive but way esayer to figger out due to being visually differant.

Recessive
----------
Normal.
Heterozygous visually same as normal.
Homozygous visually differant.
=======
Dominant.
---------
Normal.
Heterozygous visually the same as Homozygous.
Homozygous visually the same as Heterozygous.
=========
Codominant.
-----------
Normal.
Heterozygous visually differant.
Homozygous visually differant.


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## Mouki (Apr 29, 2009)

erm why can't you mix the different types of albino. 
so if you had a balbino x talbino, why would this not work???


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## Ssthisto (Aug 31, 2006)

Because although they have similar visual appearances, they are different and unrelated genes. Think of it this way: There are several reasons why a car might not run - ranging from "no petrol" to "starter motor is broken". Melanin production in geckos is similar - there's different ways to break it, from "can't produce the chemicals" to "can't find where to put the chemical when I've produced it." 

The different strains of albino break the melanin production in different ways - so if you cross "Can't produce melanin" strain to "can't find where in the skin to put the melanin" strain you get one "working" copy of each broken process - and one "broken" copy. 

That's why you don't get albinos when you cross the two strains - because the processes still have one working copy, and it's easier to make the melanin production work than it is to break it in the case of recessive Albino strains (you only need one working copy to make it work).


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## Mouki (Apr 29, 2009)

Ssthisto said:


> Because although they have similar visual appearances, they are different and unrelated genes. Think of it this way: There are several reasons why a car might not run - ranging from "no petrol" to "starter motor is broken". Melanin production in geckos is similar - there's different ways to break it, from "can't produce the chemicals" to "can't find where to put the chemical when I've produced it."
> 
> The different strains of albino break the melanin production in different ways - so if you cross "Can't produce melanin" strain to "can't find where in the skin to put the melanin" strain you get one "working" copy of each broken process - and one "broken" copy.
> 
> That's why you don't get albinos when you cross the two strains - because the processes still have one working copy, and it's easier to make the melanin production work than it is to break it in the case of recessive Albino strains (you only need one working copy to make it work).


explained!! thank you.
ive been wondering about that for a while :lol2:


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