Prophase I is one of the most important stages of meiosis.
The chromatids twist and condense , creating chromosomal structures which are visible to the microscope.
Each chromosome then actively seeks out its homologous chromosome (Double stranded chromosomes that code for the same factors: but one was from your mom and one was from your dad originally)
After the homologous chromosomes pair, the structure is referred to as a tetrad (four chromatids) BB and bb. The point at which two non-sister chromatids intertwine is known as a chiasma.
Sometimes a process known as crossing over occurs at this point. This is where two non-sister chromatids exchange genetic material. This exchange does not become evident, however, until the two homologous pairs separate.
NOTE: A pair of non-sister chromatids are chromosomes that code for the same factors
At metaphase, each chromosome has reached its maximum density (condensing).
The homologous pairs and their sister chromatids also prepare for separation
They interact with spindle fibers which form from either side of the nuclear envelope of the cell.
The spindle fibers are produced from a structure called a centriole.
There is a centriole at opposite ends of the cell, which is referred to as poles . Analogous to North and South or East and West
Metaphase I During metaphase, the chromosomes BB and bb are lined by the spindle fibers at what is known as the metaphase plate which is located in the middle of the cell As in the cell picture, it looks like a line through the center of the cell.
Sometimes Telophase I is skipped and meiosis starts its second division immediately.
In general, however, two nuclear envelopes begin to surround the separate chromosomes and cytokinesis (splitting of the cytoplasm into two separate entities) will sometimes occur. Then a phase called interkinesis will follow, which essentially is a resting period from Telophase I to Prophase II.
This differs from mitosis because DNA replication of the newly divided genetic information does not occur.
Telophase I Now cells are 1n or n meaning that B and b , chromosomes that code for the same factor have been separated from each other. 1n or n B and b separated, NOT 2n B b