You are watching: Why is meiosis called a reduction division
Interphase I: the same to Interphase in mitosis.
Prophase I: the same to Prophase in mitosis.
Metaphase I: instead of all chromosomes pairing up along the midline the the cell as in mitosis, homologous chromosome pairs line up beside each other. This is referred to as synapsis. Homologous chromosomes save the corresponding alleles donated native mother and also father. This is additionally when meiotic recombination, likewise know together "crossing over" (see below) occurs. This procedure allows for a hereditary shuffling that the characteristics of the 2 parents, producing an practically infinite variety of feasible combinations. See the close-up diagram below.
Anaphase I: rather of chromatids dividing at the centromere, homologous chromosome bag (now shuffled by crossing over) relocate along the spindle fibers to the contrary poles.
Telophase I: The cell pinches and also divides.
Prophase II: the is visibly apparent that replication has actually not occurred.
Metaphase II: The paired chromosomes heat up.
Anaphase II: The chromatids break-up at the centromere and migrate along the spindle fibers to opposite poles.
Telophase II: The cell pinch in the center and also divide again. The final outcome is four cells, each with fifty percent of the hereditary material uncovered in the original. In the situation of males, every cell becomes a sperm. In the instance of females, one cabinet becomes an egg and also the various other three come to be polar body which room not used.
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Meiotic Recombination (Crossing over):
Your parental each have at least one pair of alleles (versions the a gene) because that every properties (and plenty of pairs that alleles for each polygenic trait). You finished up with half of mom"s paired genes and fifty percent of dad"s paired genes. Yet each non-identical-twin child of these parents ends up v a various combination. Imagine, because that example, the eye color was managed by a solitary gene, and that mom can have B, the allele for brown eyes or b, the allele because that blue eyes, and dad could also have B or b. This leader to 4 possibilities: You might get B from mom and B native dad, or B indigenous mom and b native dad, or b indigenous mom and B indigenous dad, or b indigenous mom and b indigenous dad. Every sperm and also egg will finish up through either B or b indigenous mom and either B or b from dad. It"s a flip of the coin. Yet this happens individually for each trait, for this reason just since you got your dad"s brown eyes doesn"t average you"ll acquire his blond hair too. Every sibling is 50% mom and also 50% dad, but which 50% of each can vary in the siblings. This shuffling process is well-known as recombination or "crossing over" and also occurs while the chromome pairs room lined increase in Metaphase I.