Equal and Unequal Crossovers During Meiosis (image) University of Rochester Share Print E-Mail Caption During sexual reproduction, chromosomes transmitted via the mother and the father's gametes (egg and sperm) are shuffled to produce a genetic combination unique to each offspring. In most cases, the chromosomes line up properly and crossover (left panel). The unequal crossover (right panel) occurs because of "selfish DNA" sequences known as transposons, represented here as triangles. When abnormal crossovers occur, chromosomes do not line up properly and important genes may be duplicated or deleted. Credit University of Rochester illustration / Michael Osadciw Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.