Corn — a diploid organism — has been widely used to study and illustrate mendelian traits. 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 result in yellow kernels. Also in corn, the dominant gene Su produces the endosperm phenotype smooth. Smooth kernels appear hard and starchy. The recessive phenotype produces wrinkled kernels, 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.
A Brief List of Genetic Terms
Phenotype is the observable character of a cell or an organism; the observable manifestation of a gene combination.
Genotype is the specific set of genes carried by an individual cell or organism.
In homozygous dominant genotypes both genes (in diploid organisms) for a trait are the same and are dominant. This individual would exhibit the dominant phenotype.
In heterozygous phenotypes the diploid organism has one dominant and one recessive gene.
This individual would exhibit the dominant phenotype.
In homozygous recessive phenotypes both genes (in diploid organisms) are recessive. This
individual would exhibit the recessive phenotype.
Dominant is a gene that is always phenotypically expressed —it is observable— if it is present.
Dominant genes are written with an upper case letter.
Recessive is a gene that is only phenotypically expressed when the dominant gene is not present.
Recessive genes are written with a lower case letter.
Monohybrid cross is a genetic cross in which only one trait is considered....