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DESKTOP YARN MITOSIS/MEIOSIS SET UP AHEAD OF TIME: Cut yarn pieces and place in Zip-lock baggies. You may use whatever colors you like, but each kind/size of yarn below needs to be a different color. FOR THE ACTIVITY: Each individual/group will need a Zip-lock baggie containing the following: How many? 1 4 1 6 6 2 2 2 2 2 2 COLOR Black Pink Orange Purple Green Purple Purple Purple Green Green Green length 120” 20” 22” 15” 15” 4” 4” 2.5” 2.5” 1” 1” Represents Cell membrane Nuclear membranes Cell plate chromatin chromatin Chromosomes Chromosomes Chromosomes Chromosomes Chromosomes Chromosomes ACTIVITY: Walk students through the phases of mitosis and have them move the yarn pieces on their desks as each step is discussed. After they have practiced all the phases, quiz them by naming different phases and have them create them on their desks. Activity can be repeated when learning about meiosis so students can see how it is different (synapses, independent assortment, etc) INTERPHASE: (IN between dividing) (not really mitosis Set up cell membrane on desk (Use black string to make a big oval on the desk). DNA will switch back and forth between chromatin (long) and chromosomes (short) pieces during the activity. In interphase DNA is spread out as chromatin. Cells start with 6 chromosomes. (Count out 3 long purple and 3 long green strings and place in center of cell) Nuclear membrane is visible (Place pink yarn piece around the DNA) G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division During S phase DNA is copied. Hold up each chromatin yarn piece and place a "copy" along side of it. G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size (Use the 3 extra long purple/green strings) Replace DNA in nucleus PROPHASE: (First dividing phase- Pros are #1) Chromatin condenses into chromosomes (Replace longer yarn pieces in nucleus with shorter ones) Remember to keep the chromatid "copies" together. Nucleus/nucleolus disappears. (Remove pink yarn piece around chromosomes) Genetic information can be swapped between chromatids. This is crossing over and results in variation. Images by Riedell Centrioles/Spindle appear (play role of spindle with your fingers) METAPHASE (MIDDLE) Chromosomes line up in middle of cell. {Spindle (fingers) move chromosomes to middle of cell} Chromosomes line up in a random order. Another chance for variation. Image by Riedell ANAPHASE (APART) Chromatid arms separate and move to opposite ends of cell (Use fingers to separate chromatid arms) Image by Riedell TELOPHASE (TWO NUCLEI) Count chromosomes. You started with 6 (3 large, medium, small purple & 3 large, medium, small green) How many does your cell have now? (Should have 3 purple and 3 green; check to make sure you have one L, M, S purple and one L, M, S, green) Images by Riedell Chromosomes spread back out into chromatin (Replace short yarn pieces with longer yarn pieces) Nucleus/nucleolus return (Put pink string around each set of chromosomes.) Spindle/centrioles disappear. CYTOKINESIS (Cytoplasm splits) Animal cells use a cleavage furrow. (Have students push cell membrane together in middle to make two cells) Plant cells make a cell plate (Have students use their orange string to make a wall instead of pinching) Images by Riedell HOW IS MEIOSIS DIFFERENT? PROPHASE I Homologous partners match up (synapsis) and crossing over occurs Image by Riedell METAPHASE I Homologous partners line up in middle together Image by Riedell ANAPHASE I Homologous partners separate/chromatids stay together Independent assortment Image by Riedell METAPHASE II Image by Riedell ANAPHASE II Chromatids separate Image by Riedell TELOPHASE II/CYTOKINESIS Cells end up with only 3 chromosomes (one L, M, S) Independent assortment gives different color combinations