During meiosis, the chromosomes are recombined in which the chromosomes can be cut at random points and combined with another copy of a homologous chromosome, which also has cut at the same point. Thus the DNA comprises another homologous chromosome at the end.

A chromosome can contain hundreds or thousands of genes that code for different traits. All organism that reproduce by sexual methods have two copy of each chromosome, in which both the copies have same genes for the same traits, such as hair color.

Different alleles are present in each copy of chromosomes for a particular trait. For example: an allele may code for black hair and other copy for brown hair. The homologous chromosomes are the chromosomes that have same genes but may have different alleles.

Gametes including sperm and egg have only one copy of each chromosome. The cell undergo meiosis to produce haploid gametes that results in production of daughter cells with only one copy of chromosomes.

The cell then makes an identical copy of each copy and form two pairs of homologous chromosomes. The sister chromatids are the identical copies of chromosomes thus total four pairs of sister chromatids are present.

All the pairs of sister chromatids or homologous chromosomes aligns in a row during recombination. Then the recombination takes place, in which the DNA are cut and joined.

The swapping of a chunk of DNA between homologous chromosomes results in a formation of new combination of alleles. The DNA cut at random sites and form new gametes every time when meiosis occurs. The random cuts leads to numerous possible combination.

The cell divides into two in the next step and each daughter cell receives two copies of each chromosome carrying different alleles and also the recombinant DNA. The last step includes the division of cells without replication that results in forming four daughter cells, each with one copy of chromosome.