Meiosis

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=[|Cell, Socks, and Sex]=
 * [[image:http://www.accessexcellence.org/Profiles/Photos/russell.revabeth.gif width="144" height="144" link="http://www.accessexcellence.org/ae-bin/view.cgi?id=94rrusse"]] || ===RevaBeth Russell=== ||

Description:
This is a fun, easy way to teach the process of mitosis and meiosis. This will strengthen vocabulary concepts like homologus pairs, diploid, haploid, tetrad and many others. This lesson will also clear up concepts like sexual determination, trisomy and even twining.

Materials:
Four or five pairs of socks. The more used looking the better.

Lesson Plan:
I start with a long, striped piece of fabric that has been twisted hundreds of times to represent chromatin material. (Use a mixer tied to one end of fabric and the other end of the (five yards by five inch) fabric to something very stationary.) I might discuss histones and nucleosomes and how much information is coded onto the chromosomes. Next, I blow up a large, clear balloon, which I have preloaded with two identical socks, joined at the center with a Velcro "centromere". I blow up the balloon, which represents the nuclear membrane, then I pop it. The two socks represent a chromosome that has duplicated. I use socks with colored stripes, so that I can easily make reference to the genes in them, but add the idea of homologous chromosomes and alleles. I add another two socks "chromosomes" (which has finished prophase), [this is two pairs of socks for a total of three,] and I line these all up---down the middle of my body, from the top of my head to my knees (metaphase), and then pull them apart (anaphase) to the poles--my hands (teleophase). (One pair goes on my head, one pair is tucked into my neckline, another into my waist.) Each hand now has the chromatin material of an identical daughter cell. I use a similar approach to teach meiosis. I use two similar, but not identical, socks, to represent homologous pairs. One might have blue striped "genes," while the other allele has red stripes. (A non-homologus pair would be socks that have wider stripes or are sport socks as opposed to bobby socks.) The homologous pairs duplicate so I have two similar pairs, then come together (prophase I); I now have four socks, showing a tetrad and possibly a crossover. I again line this up, down the middle of my body (metaphase I) and separate (anaphase I). I finish demonstrating meiosis II to get four gametes. Now, I add the sex chromosomes to the original autosomal chromosomes. I start with "XX," which is represented by a pair of little girlUs long pink knee socks. When I finish, I have used two pair of pink socks to make four gametes, each with two autosomal chromosomes and one sex chromosome, "X." I set the "eggs" aside and demonstrate spermatogenesis, using one blue knee sock (Y) in a much smaller size and another pink sock for the X, thus making an "XY" pair. The spermatogonium with the smaller, blue "Y" chromosome does its thing, and I soon have four waiting sperm. While singing Sthe race is on and here comes Clyde in the back stretch,S the sperm swims a bit and meets the egg. (I have earlier mentioned that they have been properly married.) I do this several times, using different sperm ("X" or "Y") and different eggs, which have differently colored striped genes. The students see how sex is determined (as opposed to the students who are determined to have sex) and the variability of sexual reproduction. I then extend the activity to demonstrate nondisjunction, trisomy, haploid and diploid chromosomes, alleles, dominant and recessive autosomal traits, and homologous pairing. Often, throughout the genetics lessons, when I receive questions, I just pull socks out of the box and have the students think it through to answer their own question.

 =Chromosome Shuffle=
 * [[image:http://www.accessexcellence.org/Profiles/Photos/meyer.tamsenknowlton.gif width="144" height="144" link="http://www.accessexcellence.org/ae-bin/view.cgi?id=96tmeyer"]] || ===By [|Tamsen K. Meyer]=== ||

Modified by Tamsen Meyer from an activity using chromosome models, designed by Samantha Messier, a doctoral student in Biology at the University of Colorado and a member of the Howard Hughes Medical Institute Science Squad.

Type of Entry:

 * lesson/class activity

Type of Activity:

 * hands-on activity
 * simulation
 * group / cooperative learning
 * review / reinforcement
 * authentic assessment

Target Audience:

 * Life Science
 * Biology
 * Advanced / AP Biology
 * Special needs ( gifted, ESL )
 * Special Education

Notes to Teacher:
You will need to construct the chromosome models (two to three homologous pairs) prior to this activity. You need a large floor space ( a classroom with the desks pushed to the sides of the room) for your "cell" and an appreciation of minor chaos and lots of noise as the students move about. An initial understanding of the terminology and processes of mitosis and meiosis. One to two hours for gathering materials from the local hardware store and constructing large chromosome models. You will need at least two homologous pairs of different sizes, three would be even better. If you want, get several sets of materials and have the students construct the chromosomes and paint them. Colored tape can also be used to represent alleles on the chromosomes. Class time required: one to two 50 minute periods. You may wish to discuss mitosis and meiosis on separate days.
 * Required of the students:**
 * Preparation time:**

Abstract
Role-playing the parts of chromosomes and centrioles, students use large chromosome models and nylon cords (spindle fibers and cell membranes) to walk through the processes of mitosis and meiosis. Physical manipulation of the chromosomes and their parts in the process of cell division and replication both clarifies and reinforces some very abstract concepts for students. The goal of the activity is to compare and contrast the two cell processes so that students will understand the significance of each in living organisms.Mutations, crossing over, trisomies and other genetic events may be illustrated as well. Keep the chromosomes on your desk - you'll find many ways to use them as you teach genetics! This is the first time that students of all ability levels in my biology classes have truly understood these two types of cell division and how they are similar to and different from one another. Manipulating the chromosome models and gene segments promotes rapid understanding of a conceptually complex process. Reading difficulties are no longer an issue nor is the inability to visualize movement using diagrams. The teacher can direct, focus and question while the process occurs, and IT'S FUN!

Background
The Chromosome Shuffle activity is designed to clarify and reinforce student understanding of the cellular processes of mitosis and meiosis. Role playing using giant models of chromosomes allows students of all ability levels to model the movement of chromosomes and the action of centrioles during replication and cell division.

Project
This very simple activity uses role-playing to involve students of all ability levels in the cellular processes of mitosis and meiosis. As the teacher ( or a student!) "directs", the students will model the movement of chromosomes and centrioles during replication and cell division.
 * Chromosome Shuffle**
 * Materials:** (all available from local hardware store)


 * see Figure - these will make two homologous chromosome pairs of different lengths - quantity will depend on number of models constructed
 * 4 wooden dowels - at least 1 foot long
 * plastic tubing - 2 sizes - one that fits over each end of the dowel, a second larger tubing that will fit over the smaller tubing (the latter should be painted)
 * nylon rope - two lengths - one to form a nuclear menbrane - one to simulate the cell membrane (you may wish to have more than one cell in operation!)
 * 4 velco strips (3 inches each) - to glue around the center of each dowel
 * 4 velcro strips (8 inches each) - for chromosome pairing - wrap around center of chromosomes
 * 4 nylon cords ( 6-8 feet long) - for spindle fibers
 * 4 latch hooks and 4 eyes - these will attach chromosomes to spindle fibers and permit them to be moved
 * Procedure:**

The activity demonstrates crossing over and gene linkage. It may be extended to illustrate chromosome anomalies such as deletions and trisomies. Models can be used to show other mutation types as well as x-linkage. Each teacher will find new ways to use the models.
 * 1) Create a "cell" by moving desks/tables to the periphery of room.
 * 2) Designate 4 "chromosomes" - these students hold chromosomes, pair with homologs and exchange segments when crossing over.
 * 3) Nuclear membrane - a rope on the floor around chromosomes - may be pulled away and reformed at appropriate times by one student.
 * 4) Two students are "centrioles" - these students hold 2 nylon cords with latch hooks attached at one end. Before division these are hooked to eyes attached to the centromere on each dowel. During division, chromosomes may be moved along the floor to their new positions in the cell as division progresses. At the end of telophase, fibers are unhooked and new membranes reform around daughter nuclei.
 * 5) Student participants change roles until entire class has participated.



Method of Assessment/Evaluation
methods will vary. Teachers may wish to grade the students as they go through the task and explain what they are doing, or test understanding in a traditional manner after the activity is completed.

Extension/Reinforcement/Additional Ideas
Student groups may be assigned the task of demonstrating additional concepts for their peers using the models and other materials.