Meiosis

Terms you need to know Zygote: The fusion of sperm and egg. Gamete: A mature male (sperm) or female (egg) germ cell that is able to unite with another of the opposite sex to form a zygote. Homologous Chromosomes: are chromosome pairs, one from each parent, that are similar in length, gene position and centromere location.

Terms you need to know Synapsis: The fusion of chromosome pairs. Nuclear Membrane: is a double-layered membrane enclosing the nucleus of a cell that controls what enters and leaves the nucleus. Microtubules: are thick, strong spirals that help define cell structure and movement.

Terms you need to know Spindle Fibers: the structure that separates the chromosomes into the daughter cells during cell division. Chromatids: holds the replicated DNA of each individual chromosome, which are joined by a centromere.

Meiosis Meiosis is a special type of cell division that produces gametes with half as many chromosomes. In sexual reproduction, two parents provide an offspring with an unique gene combination. Each parent gives 1/2 of his/her genes (Chromosomes) to the offspring.

Video Clip hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535: :535::/sites/dl/free/ /120074/bio1 9.swf::Stages%20of%20Meiosis

Interphase The cell’s chromosomes have duplicated but are in the form of chromatin.

Prophase 1 Homologous chromosomes pair up and form tetrad

Prometaphase Nucleus dissolves and microtubules attach to centromeres.

Metaphase 1 tetrads of homologous chromosomes become attached to the spindle fibers and move to equator

Anaphase 1 Microtubules of the spindle fiber shorten and pull the chromosomes toward the poles, taking both sister chromatids with them.

Telophase 1 The nuclear membrane reforms around the daughter nuclei. Each daughter nucleus contains two sister chromatids for each chromosome, attached to a common centromere.

Prophase 2 Nuclear envelope breaks down and a new spindle forms.

Metaphase 2 Spindle fibers bind to both sides of the centromere.

Anaphase 2 Spindle fibers contract and the sister chromatids move toward the opposite side.

Telophase 2 Nuclear envelope reforms around the set of daughter chromosomes.

Four daughter cells are created with the perfect amount of DNA.

Mitosis/Meiosis Activity Find a partner. Each group of partner will be given a baggie with the steps to Mitosis and Meiosis. Put the different steps in order specific to the process of either Mitosis or Meiosis. Don’t use your notes!!! Once you think you have it, raise your hand for us to check!