Prior to meiosis, DNA replication occurs, so each chromosome contains two sister chromatids that are identical to the original chromosome. Meiosis is divided into two nuclear divisions: meiosis I and meiosis II. Each of these nuclear divisions shares many aspects of mitosis and can be divided into the same phases: prophase, metaphase, anaphase, and telophase, however, between the two divisions, DNA replication does not occur. Through this process, one diploid cell will divide into four haploid cells. During meiosis I. the pairs of homologous chromosomes are separated from each other. During prophase I, the homologous chromosomes line up together. During this time, crossing over canoccur(theexchangeofDNA betweenhomologous chromosomes). Crossing-over increases the new allele combinations in the gametes. Without crossing-over, the offspring would always inherit all of the many alleles on one of the homologous chromosomes. (An allele is an alternative form of a gene which is located at a specific position on a specific chromosome.) Because of crossing-over, the alleles on the homologous chromosomes can be scrambled to pass on unique combinations of alleles on the chromosome. Also, during prophase I. the spindle forms and the chromosomes condense as they coil up tightly. The spindle has the same function as in mitosis.
During prophase I, a unique process occurs. Provide the name and brief definition of this process.

Explanation

Crossing-over. Crossing-over is an exchange of genetic material between homologous chromosomes which occurs during prophase I of meiosis in a process called synapsis.