Spe rm ova Meiosis Chapter 8 Baby/Zygote

Meiosis I Meiosis is cell division but one step further, it reduces the material by half and makes a total of four cells when it is finished. This only happens in the sex cells of an organism. If an organism is not a sexual organism and reproduces by itself then this never takes place in that organism at all.

Meiosis I Interphase I cell rests and grows Prophase I doubles all material tetrad – pair of doubled, matching chromosomes. Here is where there is crossing over of traits and more Variety appears. Metaphase I all the genetic material lines up in the center of the cell, and cell structures to one side or the other.

Meiosis I Anaphase I Action stage where the materials pull apart to the poles of the cell this creates independent assortment. Telophase I and Cytokinesis I the cell pinches in and starts to clump material into the nucleus, new cell membrane forms.

Meiosis II (x 2) Prophase II Nuclear membrane disappears and the material in the cell organizes Metaphase II The chromosomes line up and the spindle fibers attach to both chromatids. Anaphase II This is where the reduction division takes place. Each chromosome will divide in half, and pull apart.

Meiosis II Telophase II Cell pinching-in takes place in each of the four cells. The new cell membrane forms and all material is moved to a new nucleus. Resulting in four new cells. Gametes Four new sex cells of gametes are formed and each has half of the first cells material and genetic information. Sperm and Eggs

Gametes Sperm – one cell makes four sperm and are functioning and able to fertilize an egg Egg (ova) – only one ova is able to be fertilized the other three cells will be smaller and will be called polar bodies and in most cases will never be able to get fertilized.

Classwork, due today: Stages How do Mitosis and Meiosis differ? Explain with pictures and examples how Mitosis and Meiosis are different?