Meiosis
MCAT glossary · Biological & Biochemical Foundations of Living Systems
Definition
The cell division producing four genetically distinct haploid gametes.
Meiosis in plain English
Meiosis is the special cell division that makes sex cells — eggs and sperm — and its whole job is to cut the chromosome count in half so that when egg meets sperm, the baby ends up with the normal full amount. 'Haploid' just means one set of chromosomes (half the usual), and it does this over two rounds of division, ending with four cells instead of two. Crucially, along the way the chromosomes shuffle and swap pieces, so all four cells come out genetically DIFFERENT from each other and from the parent — that's why siblings aren't identical. Picture shuffling a deck and dealing four unique hands rather than photocopying one hand four times.
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