Suppose Maria wants to breed parakeets that are yellow with patterned feathers. However, when she bred several parakeets that we
re yellow with patterned feathers, she found that there were four different offspring phenotypes.
Phenotype Number
patterned yellow wings 18
solid yellow wings 6
patterned white wings 6
solid white wings 2
Number of genes and alleles?
2 genes; 2 alleles each
1 gene; 4 alleles
4 genes; 1 allele each
Which phenotypes are coded for by the same gene? Different genes are separated by semicolons?
yellow and white; patterned feathers and solid
yellow and patterned feathers; white and solid
all by the same gene
each by a separate gene
Phenotype Number
patterned yellow wings 18
solid yellow wings 6
patterned white wings 6
solid white wings 2
Number of genes and alleles?
2 genes; 2 alleles each
1 gene; 4 alleles
4 genes; 1 allele each
Which phenotypes are coded for by the same gene? Different genes are separated by semicolons?
yellow and white; patterned feathers and solid
yellow and patterned feathers; white and solid
all by the same gene
each by a separate gene
1 answer:
Answer:
Explanation:
Let us start by clarifying some terms.
An allele refers to a different form of a gene, where each gene may have multiple alleles, with one coming from each progenitor. These copies need not be identical. Variants of a gene that differ from one another are recognized as alleles. A single gene can have several distinct alleles, though an individual may only present two of them at a particular locus. Certain alleles can lead to varied phenotypes (observable characteristics), with some being dominant over others.
Now, let’s arrange the alleles of our bird in a table.
From the phenotypes of her bird's chicks, it is evident that yellow is dominant over white and patterned is dominant over solid.
We will denote dominant yellow with Y, recessive white with w, dominant pattern with P, and recessive solid with s. It is common for dominant and recessive traits to use the same letter, but using distinct letters here simplifies identifying the phenotypes.
The parent birds are a dihybrid cross, representing 2 traits each linked to 2 genes, with both dominant yellow patterns expressed as PPssYYww.
Examining the chart, we find:
9 chicks exhibiting Patterned Yellow Wings
3 chicks exhibiting Solid Yellow Wings
3 chicks exhibiting Patterned White Wings
1 chick exhibiting Solid White Wings
This ratio aligns with what Maria discovered among her birds' phenotypes.
Now, let’s respond to the questions:
How many genes and alleles are there? There are 2 genes, one for pattern and another for color, while each gene has 2 alleles corresponding to pattern and color variants.
Which phenotypes are governed by the same gene?
Yellow and white; patterned and solid feathers - This can be seen from the phenotype chart; as previously noted, there are 2 genes involved, one for color and another for pattern.
Yellow and patterned feathers; white and solid
each corresponds to different genes.
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