Jack Westin MCAT Podcast

Meiosis & Gametogenesis Explained for the MCAT: Spermatogenesis, Oogenesis, Nondisjunction

11 snips
Dec 16, 2025
Dive into the intriguing world of meiosis and gametogenesis! Discover how meiosis uniquely promotes genetic diversity through processes like crossing over and independent assortment. Learn the critical differences between meiosis and mitosis, and how nondisjunction can lead to conditions like trisomy. Explore spermatogenesis step-by-step, from spermatogonia to mature spermatozoa, and understand the unique timing in oogenesis that produces one functional egg. Get essential strategies for tackling these concepts on the MCAT!
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INSIGHT

Meiosis: Two Divisions, One Replication

  • Meiosis replicates DNA once and divides twice to produce four genetically distinct haploid gametes.
  • Everything weird (crossing over, independent assortment) occurs in meiosis I, while meiosis II resembles mitosis.
INSIGHT

Tetrads And Crossing Over Create Diversity

  • Homologous chromosomes synapse in prophase I to form tetrads, enabling crossing over between maternal and paternal chromatids.
  • Crossing over produces non-identical sister chromatids and increases genetic diversity.
INSIGHT

Independent Assortment: 2^N Combinations

  • At metaphase I tetrads align randomly, producing independent assortment of maternal and paternal chromosomes.
  • Humans have 2^23 possible alignments, creating over 8 million chromosome-combination possibilities per gamete.
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