![]() These recombinant chromosomes are the DNA that parents pass to their offspring through egg cells or sperm cells. During crossing over, the chromosomes in each homologous pair swap sections of their DNA. That’s because at the very start of meiosis, a process called crossing over occurs. But what would be more accurate to say would be “ mostly maternal” and “ mostly paternal” chromosomes. What you just read immediately above focused on a “choice” between maternal and paternal chromosomes.I’ll expand on its mechanism and consequences below. This process is called independent assortment. In other words, for the first homologous pair, the choice of which chromosome gets sent to the gamete might be the paternal chromosome, while for the second pair it might be the maternal chromosome. And, most importantly, what happens with each pair is independent of every other pair. The choice is this: for each homologous pair, which chromosome (maternal or paternal) will be sent to the haploid gamete?Īs we’ll see, for each pair, the choice is random: it’s essentially a coin toss. As meiosis reduces chromosome number from diploid (two sets) to haploid (one set), a cellular “choice” has to be made.How does meiosis create variation? In terms of the actual, cellular processes, two things occur: Meiosis is why you’re genetically different from your parents. Meiosis and fertilization ensure that each generation is genetically different from the parent generation that created it. A vertical dimension (between generations).If you have a biological brother or a sister, meiosis is the reason why you’re genetically different- despite having the same parents. In any family, meiosis and fertilization are why the offspring in that family are genetically different from one another. A horizontal dimension (within a generation).You can think of this variation as having two dimensions: In any sexually reproducing species, meiosis creates genetic variation That second idea is going to be the focus of this tutorial. Here’s a second idea: meiosis, along with fertilization, creates genetic variation. ![]() One key idea to take away from everything that we’ve learned about meiosis so far is that meiosis reduces chromosome number from diploid to haploid. Introduction: Meiosis Creates Genetic Variation
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