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Name __________________________________ Date _________________ Period _______
Meiosis: ACTIVITY
(What Gregor Mendel Didn't...
3. During Prophase I, the homologous pairs line up next to each other. They usually get so close that parts of them
wrap a...
6. In Telophase I, the chromosomes are
at opposite ends of the cell. Just after
Telophase I the cell divides.
Draw your tw...
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Meiosis activity

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Meiosis activity

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Meiosis activity

  1. 1. Name __________________________________ Date _________________ Period _______ Meiosis: ACTIVITY (What Gregor Mendel Didn't Know) Introduction: Gregor Mendel made some remarkable discoveries about how traits are passed from parents to their offspring. However, Mendel couldn't explain what was physically happening within cells to pass these traits on because he didn't know anything about chromosomes. This wasn't Mendel's fault: microscopes weren't good enough when he was alive to see chromosomes. No one knew then that DNA was the molecule that contained genes and that it was contained inside chromosomes in cells. Now that we know that genes are coded in DNA inside chromosomes, we can explain why genes do all the things Mendel said they did hundreds of years ago. By understanding what happens to the chromosomes when sperm and eggs are formed, we can understand why children look a little bit like their parents but are not identical to them. During this simulation, you will only be looking at what happens to the chromosomes during meiosis; the centrioles, nucleolus, and nuclear membrane also undergo important changes (just like they do in mitosis), but for the sake of simplicity, they will not be looked at in this activity. When you draw pictures, make sure you color code and size code them; this will make it easier to understand what is happening. **YOU MUST COLOR CODE ALL YOUR PICTURES AND DRAW THE SIZES OF CHROMOSOMES CORRECTLY!!! ** Ex) Directions: 1. Set up your original cell: In the center of your table put one short green pipe cleaner and one long green pipe cleaner; one short red pipe cleaner and one long red pipe cleaner. The red pipe cleaners came from this cell's Mom; the green pipe cleaners came from Dad. The total number of chromosomes of this cell = _________ How many homologous pairs does this cell have = _________ 2. During Interphase the DNA replicates and the chromosomes double. Put the other pipe cleaners next to the ones already in your "cell" to show the doubled chromosomes. Twist them together to show the centromere. Draw your chromosomes here: COLOR CODE!! You need to use two different colors, (they do not have to be red and green).
  2. 2. 3. During Prophase I, the homologous pairs line up next to each other. They usually get so close that parts of them wrap around each other and exchange pieces (called crossing over). Put the "homologous" pipe cleaners next to each other, and wrap their tips around each other. Draw your chromosomes here: label the homologous pairs and CIRCLE where crossing over is happening COLOR CODE!! 4. In Metaphase I, the chromosomes line up in the middle of the cell. They line up differently than they do in mitosis, though. If you were to draw an imaginary line down the middle of the cell, one doubled chromosome of each homologous pair would be on each side of the line. CHECK THIS ARRANGEMENT WITH YOUR TEACHER BEFORE CONTINUING! There are 2 ways in which your chromosomes can be arranged. Draw both ways but continue on with only one of the two arrangements. Also, draw a dotted line between the homologous pairs to illustrate the metaphase “plate”. COLOR CODE!! First Arrangement Second Arrangement 5. In Anaphase I, chromosomes move towards opposite sides of the cell, but the doubled chromosomes stay attached at their centromeres. How is this different from Anaphase in mitosis? Will the two new cells be genetically identical to one another? ___________ WHY? EXPLAIN below
  3. 3. 6. In Telophase I, the chromosomes are at opposite ends of the cell. Just after Telophase I the cell divides. Draw your two new cells: COLOR CODE!! ** How many chromosomes does each new cell have? __________, ( or _______ pairs of sister chromatids). 7. The two new cells go through the second stage of meiosis, which is just like mitosis. Do the chromosomes double again before the second division? __________ EXPLAIN YOUR ANSWER BELOW. 8. Draw pictures of what the four new cells would look like at the end of the second division of meiosis. COLOR CODE!! ** How many chromosomes does each cell have? _____________ SUMMARY QUESTIONS: 1. One of the main purposes of meiosis is to cut the chromosome number in half. a. Why does the chromosome number need to be cut in half? b. During which phase of meiosis does the chromosome number get halved? ____________________ (Consider that a "doubled" chromosome does not really count as two chromosomes because it is just a duplicate of the first with all the same genes. ) 2. In human cells, the diploid number of chromosomes is 46. How many chromosomes would be in a human sperm cell? _______________

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