Multiple alleles makes for many possible dominance relationships. In this case,
ID: 165799 • Letter: M
Question
Multiple alleles makes for many possible dominance relationships. In this case, the
black C allele is completely dominant to all the others; the chinchilla cch allele is
incompletely dominant to the Himalayan ch and albino c alleles; and the Himalayan ch
allele is completely dominant to the albino c allele.
Why is C dominant over the others? (Hint: It is similar to alleles for blue and brown eyes.)
Which allele is completely recessive? Explain why.
Mendel's work suggested that just two alleles existed for each gene. Today, we know that's not always, or even usually, the case Although individual humans (and all diploid organisms) can only have two alleles for a given gene, multiple alleles may exist in a population level, and different individuals in the population may have different pairs of these alleles. As an example, let's consider a gene that specifies coat color in rabbits, called the C gene. The C gene comes in four common alleles: C, ch ch, c ACC rabbit has black or brown fur A cch och rabbit has chinchilla coloration (grayish fur) A ch ch rabbit has Himalayan (color-point patterning, with a white body and dark ears, face, feet, and tail A cc rabbit is albino, with a pure white coat. Genotype CC chcch chch CC Phenotype BLACK CHINCHILLA HIMALAYAN ALBINOExplanation / Answer
The words "Dominant" and "recessive" are used to describe the Phenotipic expression. Phenotype means what will be seen in an individual. In the case of fur colouration in rabbits the allele CC expresses is" BLack". So even if the Genotype is Cch or Cc or Ccch, the main colour seen will be BLACK interspersed with gray and white. Since the presence of one allele "C'' expresses the Phenotype Black ,C allele is said to be dominant over others.
The allele pair "cc" is completely recessive. This is so because only when it is present in a pair it is able to express itself, an albino with no other colour except pure white. If it occurs with ch the fur becomes patterned with gray and if it occurs with cch the fur colour is Grayish.
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