Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Prophase I is the first phase in meiosis I where chromosomes condense, homologous chromosomes pair up to form tetrads, and crossing over occurs.
Related terms
Tetrad: A tetrad is a four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each composed of two sister chromatids.
Synapsis: Synapsis is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation.
Chiasmata: Chiasmata are the points where crossing over occurs between two nonsister chromatids in a tetrad during meiosis.