HS-LS3-3. Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population. [Clarification Statement: Emphasis is on the use of mathematics to describe the probability of traits as it relates to genetic and environmental factors in the expression of traits.] [Assessment Boundary: Assessment does not include Hardy-Weinberg calculations.]
Introduction - In corn, the dominant gene R, determines the presence of colored aleurone. Individuals possessing one copy of the gene will exhibit purple kernels. Recessive phenotypes (r) result in yellow kernels. In addition, the dominant gene Su produces the endosperm phenotype smooth. Smooth kernels appear hard and starchy. The recessive phenotype produces wrinkled kernels (su), which are shrunken in appearance.
In this lab, we will examine the mode of inheritance of these two genes by looking at the progeny of a fertilization event between a male corn flower and a female corn flower. Each kernel is the progeny of one of such fertilization events. By counting the different kernel types, we should be able to determine their pattern of inheritance.
The purple color is produced by a pigmented layer within the grains. If the layer is not pigmented (colorless), the yellow color of an inner tissue shows through. Sweet corn grains wrinkle upon drying while starchy grains remain smooth. Individual kernels may be (A) purple—starchy, (B) purple—sweet, (C) yellow—starchy, or (D) yellow—sweet. Because these traits are easy to see, a monohybrid or dihybrid cross provides a very easy way to see if these traits are inherited independently (Law of Independent Assortment, Mendelian), or are linked (Non-Mendelian).
Question - Are the genes for color and smoothness inherited independently (on different chromosomes) or are they linked (on the same chromosome)?
enter your data here.
Collect and enter data - Examine an ear of corn was produced by a dihybrid cross involving two pairs of heterozygous genes Count the number of each type of kernel and
Analyze your data
Analyze class data - Analyze the entire set of class data.
Examine summary data - Examine summary data. Does the data suggest a 9:3:3:1 Mendelian ratio?