Molecular basis of the wrinkled seed coat mutation The wrinkled seed coat mutant is due to the insertion of a foreign sequence in the wild type smooth seed coat gene. As a consequence, the mutant gene is longer and runs slower in a size-separation gel.
Results of a monogenic genetic cross (involving 2 alleles of the same gene)
A human pedigree showing the inheritance of a dominant disease gene. The diseased individuals are present in every generation (indicates a dominant disease) and males and females are both about equally affected (indicates autosomal inheritance)
Inheritance of an autosomal recessive disease gene The heterozygous individuals are phenotypically wild type. In this pedigree, there are only 3 affected individuals (III.2, III.4, IV.5). Mating of two heterozygotes is required to produce an affected child.
A human pedigree showing the inheritance of a polymorphic DNA marker There is no masking of one allele by another allele for DNA markers (codominance of alleles is seen)
Independent assortment of alleles for 2 different genes yields 4 kinds of gametes in 1:1:1:1 ratio in all organisms (peas and humans, for example). Mendel’s laws apply to all organisms because the mechanisms of meiosis and fertilization are the same
Incomplete dominance between 2 alleles of the same gene yields a 1:2:1 phenotypic ratio in F 2 (not 3:1)