Concept explainers
Pigeons may exhibit a checkered or plain color pattern. In a series of controlled matings, the following data were obtained.
Then ⊢1 offspring were selectively mated with the following results. (The P1 cross giving rise to each ⊢1 pigeon is indicated in parentheses.)
How are the checkered and plain patterns inherited? Select and assign symbols for the genes involved, and determine the genotypes of the parents and offspring in each cross.
To determine: The pattern of inheritance of checkered and plain pattern.
Introduction: Pattern of inheritance is defined as the pattern by which a particular trait or gene is transferred to the offspring and what are the conditions that is needed for its expression. There are five different types of pattern of inheritance namely X-linked dominant, X-linked recessive, autosomal recessive, autosomal dominant and mitochondrial inheritance.
Explanation of Solution
In the cross between checked and plain pattern shows a autosomal dominance inheritance in which checkered trait is a dominant trait and plain pattern is a recessive trait. This can be concluded because in a cross between checkered and plain pattern parents give all heterozygous offspring and since checkered trait being a dominant trait is expressed in all heterozygous progeny.
The inheritance pattern of offspring produced by crossing checkered and plain pattern parents is autosomal dominance inheritance.
To determine: The pattern of inheritance of checkered and plain pattern.
Introduction: Mendel gave three important postulates by observing the monohybrid crosses and Law of dominance is one of the three laws given by Mendel. According to this law a dominant trait expresses itself in both homozygous condition as well as heterozygous condition. On the contrary, the recessive trait is able to express only in homozygous condition.
Answer to Problem 1NST
Pictorial representation: Fig.1 cross showing the F1 and F2 progeny formed after crossing between checkered and plain pigeons.
Fig.1: Crosses show the F1 and F2 progeny formed after crossing between checkered and plain pigeons.
Explanation of Solution
The dominant trait responsible for checkered pattern is represented by “A” and the recessive trait responsible for plain pattern is represented by “a”.
In the F2 cross when the F1 progeny is crossed with each other the cross between checkered (a) and plain gave 34 checkered and no plain progeny. When the checkered b progeny is crossed with the plain progeny 17 checkered and 14 plain progeny were formed. When checkered (b) is crossed with itself, 28 checkered and 9 non checkered progeny were formed and when checkered (a) and checkered (b) are crossed 39 checkered offspring’s were formed.
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