Mendelian explanation for bicolor coated puppy

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SUMMARY

The discussion centers on the genetic explanation for a bicolor coated puppy, specifically one with black and white fur. It identifies the dominant genes for white (W) and black (B) colors, alongside their recessive counterparts (w and b). The concept of 'mosaicism' is introduced as a key factor, where different genes are expressed in different cells, leading to varied fur coloration. This phenomenon is notably observed in tortoiseshell cats, where X chromosome inactivation plays a crucial role in determining the coat color.

PREREQUISITES
  • Understanding of Mendelian genetics, including dominant and recessive traits.
  • Familiarity with the concept of mosaicism in genetics.
  • Knowledge of X chromosome inactivation and its implications in female mammals.
  • Basic principles of DNA methylation and gene expression.
NEXT STEPS
  • Research the mechanisms of X chromosome inactivation and its effects on phenotype.
  • Explore the concept of mosaicism in various organisms beyond mammals.
  • Investigate the genetic basis of coat color in tortoiseshell cats.
  • Learn about the role of DNA methylation in gene regulation and expression.
USEFUL FOR

Geneticists, veterinarians, animal breeders, and anyone interested in the genetic mechanisms behind coat color variations in dogs and other animals.

Medicol
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1. Mendelian experiments only explain dominant vs recessive gene ratios after generations created by assorted types of mating. But how can I explain the puppy's bicolor coat of black and white given that its parents are one black and one white



2. Supposing that W and B are dominant genes of white and black colors and so 'w' and 'b' are recessive ones. What is the puppy's with a dotted coat ?



3. The Attempt at a Solution . I wish to but truly I don't know
 
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Medicol said:
1. Mendelian experiments only explain dominant vs recessive gene ratios after generations created by assorted types of mating. But how can I explain the puppy's bicolor coat of black and white given that its parents are one black and one white
2. Supposing that W and B are dominant genes of white and black colors and so 'w' and 'b' are recessive ones. What is the puppy's with a dotted coat ?
3. The Attempt at a Solution . I wish to but truly I don't know
The word for it is 'mosaicism'. It happens when different genes of the diploid genome are expressed in different cells and their cellular descendants. It happens most famously with X chromosomes in females. One of the X chromosomes in the XX cells has to be inactivated as otherwise the cell gets an overdose, since one X works in males so that is the right dosage for these genes. The X chromosome inactivation happens by DNA methylation. But it happens some way along the developmental pathway e.g. When there are a dozen or two precursors of the pigment-producing cells, and happens randomly so in some cells one chromosome is inactivated and go on to produce one fur colour, in others the other. Although female's tissues are mosaic for all X-chromosome products, in most cases this would not produce any such obviously noticeable phenotypic effect.

The most well known case is very similar to your example - tortoiseshell cats.

There are other mosaicism mechanisms though.

Follow up with google the various bolded keyphrases.
 
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