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Discussion in 'General breed discussions & FAQ' started by Bantimna, Nov 24, 2009.
Whats the diffrence between ressiseve whit and dominate white?
They are two unrelated genes. Recessive white is very good at inhibiting pigment; dominant white is very leaky.
Whats that mean?
Explain how much you do/don't know about genetics so we can explain at the right level.
Okay what I don't know is the e^e etc... that type of stuff but I do know that....... let me just say this I'm young trying to learn about genetics but don't know anything.....I'm willing to learn but will most probbally catch on. with what you say. Oh I must say I know dominate and ressisve white in Budgies.
A bird needs two copies of the recessive white gene to make the bird white. Sometimes when you cross two black birds they can have recessive white chicks. When a chick inherits two recessive white genes, the genes switch off the chemical pathways that make black or red pigments so you get a white bird. The bird can have the genes that would make it black or red but the recessive white genes prevent the birds cells from making red or black pigments.
Dominant white is different because it tries to switch off the chemical pathways but does not do a very good job. It is good at switching off the pathway that makes black but has a hard time turning off the chemical pathway that makes red. This causes some of the red pigment to leak through the white.
Sometimes the dominant white gene only switches off the black for a short time then allows the black to switch back on so you do get some black pigment in the feathers. In order to get rid of the black completely, breeders will add additional genes to a bird that also turn off the chemical pathway that makes black pigment.
In order to keep dominant white birds white, breeders want the genes in the bird that make black pigment and not red pigment. You could say that the dominant white bird is black under the white. The bird has the genes to make black feathers but the dominant white gene or genes like barring and silver turn off the chemical pathways that make the black pigments.
You can say recessive white genes really do not need help from other genes to make a bird white but the dominant white gene needs help from genes like silver and barring.
I will try to start with very basics. My apologies if I am too simple.
Every creature with two parents has two sets of chromosomes: one inherited from each parent. Except for the sex chromosomes, the chromosomes are matched pairs, each containing locations for specific genes. These non-sex chromosomes are referred to as being autosomal.
Within each location on a chromosome, a set of specific variations can occur. Sometimes there are only two alternatics, sometimes many. These variations are referred to as alleles. For the blue gene (since that seems to be the most commonly explained) there are two alleles: blue and not-blue. Blue is abbreviated Bl, using a capital letter because it is dominant over the alternative allele, not-blue, which is abbreviated bl+. The + indicated that this allele is wild-type. Because chromosomes are paired, each bird carries two copies of a blue allele. They can be two copies of Bl, two copies of bl+ or one of each. When both alleles are the same, it is referred to as being homozygous; when they are different it is heterozygous.
So, each location holds a different gene, of which there can be several variations.
Kind of like a row of houses, each with a different family. Only the Adams live at the Adams' house, only the Browns live at the Brown's house, only the Carlisles live at the Carlisle's house. But, at the Adams there can be Mr Adams, or Mrs Adams, or Baby Alex Adams; at the Browns you might find Aunt Beatrice Brown, Uncle Bob Brown or Cousin Betty Brown. etc.
Transfering this analogy to chicken genes, Dominant White would be one house, and living there are Smokey (I^S) Dominant White (I), Dun )I^D), and not-White (i+). Another house is home to the Recessive Whites: Colour (C+), not-colour (C), red-eye (C^re) and albino (c^a). And yet a third house is home to the Extended Blacks: Extended (E), Birchen (E^R), Wheaten (e^Wh), not-extended (e+) and Brown (e^b). Now the rules of this little universe are somewhat complex, but everyone has an identical twin who lives at their home. Also, in most cases, exactly two of the family is always home. In a few cases for a few homes, only one person can be at home.
As in all families, each gene-family has their own traditions and rules, and each family member has their own personality.
WELL PUT!! Thanks to both off you!
I'm need to start following your posts.
tadkerson: You always put it so well.
Sonoran Silkies: Great simile! It really gives a good visual.
thanks again, I always learn a lot when I listen to you two
Tim and Suze are BOTH Great Teachers!
Thanks, from me too!
Thank you so much my little brain is on overload I have to keep this bookmarked thank you so much