Meiosis

What is Meiosis? Meiosis produces sex cells in both males (sperm) and females (eggs). Organisms that reproduce sexually have more diversity. The number of chromosomes are reduced by half to form sex cells (sperm and eggs).

Chromosomes Each cell in the body contains 46 chromosomes except for the sex cells which contain only 23.

Process Begins Step 1 Meiosis starts when the genetic material within the cell is duplicated (copies). This is called Prophase I.

The chromosomes line up in the center of the cell. Stages of Meiosis Step 2 The chromosomes line up in the center of the cell. This is called Metaphase I.

Step 3 The chromosome pairs separate and move to the opposite end of the cell. Form PEANUT shape. This is called Anaphase I.

Step 4 Two cells are formed, each with half the number of chromosomes. Each chromosome still contains its 2 chromatids. This is known as Telophase I.

What is a Chromatid? Chromatids are formed when Chromosomes multiply. They are held together by a Centromere.

Step 5 The chromosomes move to the center of the cells. This is called Metaphase II.

Step 6 The centromeres split and the chromatids separate. The single chromatids move to opposite ends of the cell. This is called Anaphase II.

Step 7 (End of Meiosis) The cells separate to form 4 sex cells that contain half the number of chromosomes that the parent cell had. This is called Telophase II.

All together

Importance The process of Meiosis is important because this illustrates to us how we get half of our genes (23) from our Mom, (23) from our Dad and we end up with 46. This is why parents can have certain traits and children not be born with them. Punnett squares help us visualize all the combinations that can come from two parents’ genes.