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What is the roan cattle and the Jappanese four o'clock ???

Genetics as it applies to evolution, molecular biology, and medical aspects.

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What is the roan cattle and the Jappanese four o'clock ???

Postby 09MillerLr » Wed Mar 01, 2006 11:55 pm

i don't qite understand this my teacher brought it up but didn't tell us what it ment it was one of our objectives... we have to figure them out..some how
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Postby kiekyon » Fri Mar 03, 2006 1:54 am

cattle hair color shows codominance. red is dominant, and white is recessive. in the heterozygous condition codominance is shown as a roan (something of a light red) coat color.

four o'clock plant also known as mirabilis jalapa. not sure where you get the 'japanese' though. anyway it also shows codominance. again red is dominant, white is recessive. in the heterozygous condition codominance is shown as pink in colour.

both are classic cases of codominance
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Postby WVB » Tue Aug 22, 2006 10:22 pm

Probably too late but ...
Actually, the four o'clocks display what is called Incomplete Dominance (where only one of the two alleles contributes to the phenotype), and the heterozygote is intermediate in phenotype due to a dosage effect -- it only makes half as much pigment as its homozygous pigmented parent.
Codominance is where both alleles (e.g., wildtype and mutant) produce a gene product, again giving an intermediate phenotype but as a result of "blending" (with apologies to Mendel).
Incomplete Dominance and Codominance can be very difficult to distinguish at the phenotype level -- may need molecular/biochemical information to be absolutely sure.
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