Page 19 - Science E-Book Prep.3 2024-2025 1st term_Neat unit 3,4

Science Department
Prep.3

Prophase I:

1. Chromatin reticulum condenses & appears as chromosomes.

2. Chromosomes are arranged in homologous pairs, each pair formed of
four chromatids. (Tetrads).

3. Crossing over phenomenon occurs

4. Nuclear membrane and nucleolus disappear.

5. Each two homologous chromosome in
the tetrads move away from each other
spindle fibers appears and connect to
chromosomes at centromere.

Metaphase I:
-Chromosomes pairs arrange at the cell equator (Middle)

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First Term