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Mitosis Desk Models ActivityName______
Read this first: Use the kit in the baggie to show how mitosis occurs. Follow the directions in the “Phase” column and answer questions in “Major Events”
PHASE / Major Events(Focus on answering the questions below)
#1 INTERPHASE (This is NOT actually one of the 4 phases of Mitosis)
INTERPHASE: (“IN between dividing”) Set up cell membrane on desk (Use the 2 long yarn pieces to make a big oval on the desk). DNA will switch back and forth between chromatin and chromosomes (represented with fuzzy wire) pieces during the activity. In interphase, DNA is spread out as chromatin. Your cell will start with 3 chromosomes. (Count out 3 different colors of fuzzy wire pieces and place in center of cell.) Nuclear membrane is visible (Place shorter yarn piece around the DNA) in this stage. Place the beans in the cytoplasm space to represent centrioles.
/ 1) What can you see in the nucleus of the cell?
2) Is a nucleus visible within the cell?
#2 PROPHASE
During “S” phase of interphase, DNA is copied. Hold up each fuzzy chromatin piece and place a "copy" along side of it (it is not yet shaped like an X, though.) Replace chromatin back in nucleus.
PROPHASE: (First true phase of mitosis: “Pros are #1”) Chromatin condenses into chromosomes (twist the fuzzy wires into an X to make 3 chromosomes) Remember to keep the sister chromatid "copies" together. Nucleus/nucleolus disappears. (Remove short yarn piece around chromosomes)
Spindle fibers appear and extend out from the centrioles. (Cluster the thin string around the beans.)
/ 3) What is happening to the nucleus during prophase?
4) What is happening to the chromatin?
#3 METAPHASE
METAPHASE: (“MIDDLE”) Chromosomes line up in middle of cell. Spindle fibers from centrioles hold the chromosomes in the center of the cell in a line. (Beans should be on opposite sides of the cell. Extend strings from the beans so the string touches the center of the chromosome at the centromere.)
/ 5) What are the chromosomes doing in metaphase?
6) What has happened to the position of the centrioles since prophase?
#4 ANAPHASE
ANAPHASE: (“APART”) Chromatid arms separate and move to opposite ends of cell. Spindle fibers from the centrioles push and pull the chromosome until it separates at its centromere. (Use fingers to separate chromatid arms, pushing them with their strings toward the bean centrioles.) The cell is elongating as the chromosomes separate. (Spread the long yarn out into a bigger oval.)
/ 7) What are the spindle fibers doing?
#5 TELOPHASE & #6 CYTOKINESIS
TELOPHASE: (“TWO NUCLEI”) Count chromosomes. In prophase, you started with 6 sister chromatids that made 3 chromosomes. Chromosomes spread back out into chromatin. The nucleus returns. (Put a strand of shorter yarn around each set of chromosomes.) Spindle/centrioles disappear. (Remove the thin strings.)
/ 8) Your cell is now looking like a very long cell with two clumps of chromosomes in it. Is the nucleus returning to be visible in the cell?
9) What is happening to the chromosomes that is the opposite of what happened during prophase?
CYTOKINESIS: (“Cytoplasm splits”) To finally split into two, animal cells use a cleavage furrow, which acts like an invisible string that pinches the cell into two. (Push cell membrane together in middle to make two cells). Plant cells make a cell plate.
Put all pieces back into your baggie kit and bring it up to your teacher for clean-up. / 10) How do plant and animal cells differ with regard to splitting into two new cells?