Question

Even in the absence of genetic recombination, meiosis is an important source of genetic variation in sexually reproducing organisms. Use as an example a species with 2n=8, and an individual of that species that is a quadruple heterozygote for loci A, B, C, and D, with each loci on a different chromosome. Determine how many different types of gametes this individual can produce, and explain how segregation and independent assortment mechanisms produce genetic variation in the gametes produced by this individual. Use the following terms in your response: genes; alleles; homologous chromosomes; non-homologous chromosomes.

Answer 1

The number of possible gametes are 2^n . Here n is equalt to the number of heterozygous genes. Here 4 heterozygous genes A, B, C and D is present.

The number of possible gametes are 2^4 = 16

The genetic vatiation is produced in the meiosis during gamete formation. During the metaphase 1 of meiosis 1, the homologous chromosome are aligned in independent manner in the two equatorial plate. The non homologous chromosome are found on the same plate where as homologous chromosome are found at different plates. There are 16 ways of alignment of chromosomes are found in metaphase 1. These aligned chromosome are segregated towards each pole during anaphase 1. Hence in ecah daughter cells there are found four chromosome out of 8 chromosome. After that each daughter cell undergoes meiosis 2, the centromere is splitted and each chromatids are segregated towards each pole. This independent assortment and segregation produces 16 kinds of gametes.