what process results in an exchange of genes between homologous
Chromosomal crossover
title: Homologous chromosome text: Cohesin crosslinking occurs between the homologous chromosomes and helps them resist being pulled apart until anaphase. Genetic crossing-over, a type of recombination, occurs during the pachytene stage of prophase I. In addition, another type of recombination referred to as synthesis-dependent strand annealing (SDSA) frequently occurs. SDSA recombination involves information exchange between paired homologous chromatids, but not physical exchange. SDSA recombination does not cause crossing-over. In the process of crossing-over, genes are exchanged by the breaking and union of homologous portions of the chromosomes’ lengths. Structures called chiasmata are the site of the exchange. Chiasmata physically link the homologous chromosomes once title: Chromosomal crossover text: Chromosomal crossover Chromosomal crossover (or crossing over) is the exchange of genetic material between 2 homologous chromosomes non-sister chromatids that results in recombinant chromosomes during sexual reproduction. It is one of the final phases of genetic recombination, which occurs in the "pachytene" stage of prophase I of meiosis during a process called synapsis. Synapsis begins before the synaptonemal complex develops and is not completed until near the end of prophase I. Crossover usually occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome. Crossing over was described, in theory, by Thomas Hunt Morgan. He relied title: Homologous recombination text: used in horizontal gene transfer to exchange genetic material between different strains and species of bacteria and viruses. Although homologous recombination varies widely among different organisms and cell types, most forms involve the same basic steps. After a double-strand break occurs, sections of DNA around the 5' ends of the break are cut away in a process called "resection". In the "strand invasion" step that follows, an overhanging 3' end of the broken DNA molecule then "invades" a similar or identical DNA molecule that is not broken. After strand invasion, the further sequence of events may follow either of two title: Meiosis text: 1c). Prophase I is typically the longest phase of meiosis. During prophase I, homologous chromosomes pair and exchange DNA (homologous recombination). This often results in chromosomal crossover. This process is critical for pairing between homologous chromosomes and hence for accurate segregation of the chromosomes at the first meiosis division. The new combinations of DNA created during crossover are a significant source of genetic variation, and result in new combinations of alleles, which may be beneficial. The paired and replicated chromosomes are called bivalents or tetrads, which have two chromosomes and four chromatids, with one chromosome coming from each parent. The title: Homologous recombination text: Homologous recombination Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA. It is most widely used by cells to accurately repair harmful breaks that occur on both strands of DNA, known as double-strand breaks (DSB). Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to adapt during the course of evolution. Homologous recombination is also