What helps ensure the survival of a species?
Genetic variation. The is this variation the is the essence of evolution. Without hereditary differences amongst individuals, "survival of the fittest" would not it is in likely. Either all survive, or all perish.
You are watching: Exchange of genes between homologous chromosomes
During prophase I, chromosomes condense and also become visible inside the nucleus. Together the nuclear envelope begins to rest down, homologous chromosomes move closer together. The synaptonemal complex, a lattice of proteins between the homologous chromosomes, develops at specific locations, spreading to sheathe the entire length the the chromosomes. The tight pairing of the homologous chromosomes is dubbed synapsis. In synapsis, the genes on the chromatids of the homologous chromosomes space aligned through each other. The synaptonemal complicated also support the exchange that chromosomal segments in between non-sister homologous chromatids in a process called cross over. The crossover occasions are the very first source of hereditary variation produced by meiosis. A solitary crossover event in between homologous non-sister chromatids leader to an exchange that DNA between chromosomes. Adhering to crossover, the synaptonemal complicated breaks down and the cohesin connection in between homologous bag is likewise removed. At the end of prophase I, the pairs are organized together just at the chiasmata; lock are dubbed tetrads since the four sister chromatids of each pair the homologous chromosomes are currently visible.
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