Crossing over in meiosis results in genetic recombination, which is responsible for the genetic diversity of a population. Genetic recombination and natural selection are the driving forces behind evolution. It causes most of the differences between parents and their offspring and differences between siblings.Know More
Meiosis, otherwise known as sex cell division, creates unique gametes, which are eggs in females or sperm in males, from existing DNA in eukaryotes. For meiosis to occur, the chromosomes contributed by each of the organism's parents are duplicated to form sister chromatids. During meiosis I, the sister chromatids of one parent match up with the corresponding sister chromatids of the other parent, or its homologous non-sister chromosome, along the metaphase plate. Crossing over then occurs. At a point called a chiasma, homologous chromosomes trade genetic information so that each chromosome is complete but has different information. This random exchange of information is what allows for unique gametes to form and genetic recombination to occur.
Sometimes, however, too few crossing over events can result in abnormally short or long chromosomes, meaning that there is too little or too much information. If a gamete with this type of chromosome is fertilized, abnormalities in the offspring are likely.Learn more about Cells
Meiosis is important because during sexual reproduction, it ensures that all produced organisms have the correct number of chromosomes. It is also responsible for producing genetic variations during the process of recombination, and it repairs some genetic defects.Full Answer >
Chromosome numbers do not halve during mitosis, and genetic recombination does not occur during mitosis. Mitosis results in the formation of two identical daughter cells with a full set of chromosomes, rather than sex cells.Full Answer >
A bottleneck effect is an ecological phenomenon in which the population of a species is drastically reduced to the point where the species is still able to carry on, but the genetic diversity of the species is severely limited. This type of event only occurs when members of the population are killed at random, and their death has nothing to do with genetic flaws or inability to adapt.Full Answer >
A tetrad is a composition of four chromatids that are formed after synapsis occurs during the prophase I stage of meiosis I. Each of the tetrads contains two chromosomes, known as a homologous chromosome pair, with two chromatids per chromosome.Full Answer >