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Chromosomal DNA Movement through Meiosis

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Experiment 1: Following Chromosomal DNA Movement;through Meiosis;In this experiment, you will model the movement of the chromosomes through;meiosis I and II to create gametes.;Materials;2 Sets of Different Colored Pop-it Beads (32 of each - these may be;any color);(8) 5-Holed Pop-it Beads (used as centromeres);Procedure;Part 1: Modeling Meiosis without Crossing Over;As prophase I begins, the replicated chromosomes coil and condense;1. Build a pair of replicated;homologous chromosomes. 10;beads should be used to create;each individual sister chromatid;(20 beads per chromosome pair).;The five-holed beads represent;each centromere. To do this...;a. Start with 20 beads of the;same color to create your;Figure 3: Bead set-up. The blue beads;first sister chromatid pair.;represent one pair of sister chromatids;and the black beads represent a second;Five beads must be;pair of sister chromatids. The black and;snapped together for each;blue pair are homologous.;of the four different strands.;Two strands create the first chromatid, and two strands create the;second chromatid with a 5-holed bead at the center of each;chromatid. This creates an I shape.;b. Connect the I shaped sister chromatids by the 5-holed beads to;create an X shape.;2013 eScience Labs;LLC.;All Rights Reserved;2.;3.;4.;5.;6.;c. Repeat this process using;20 new beads (of a;different color) to create the;second sister chromatid;pair.;Assemble a second pair of;replicated sister chromatids, this;time using 12 beads, instead of;20, per pair (six beads per each;complete sister chromatid strand).;Figure 4: Second set of replicated;Pair up the homologous;chromosomes.;chromosome pairs created in Step;1 and 2. DO NOT SIMULATE;CROSSING OVER IN THIS TRIAL. You will simulate crossing over in Part;2.;Configure the chromosomes as they would appear in each of the stages of;meiotic division (prophase I and II, metaphase I and II, anaphase I and II;telophase I and II, and cytokinesis).;Diagram the corresponding images for each stage in the sections titled;Trial 1 - Meiotic Division Beads Diagram. Be sure to indicate the number;of chromosomes present in each cell for each phase.;Disassemble the beads used in Part 1. You will need to recycle these;beads for a second meiosis trial in Steps 7 - 12.;Trial 1 - Meiotic Beads Diagram;Prophase I;Metaphase I;Anaphase I;Telophase I;2013 eScience Labs;LLC.;All Rights Reserved;Prophase II;Metaphase II;Anaphase II;Telophase II;Cytokinesis;Part 2: Modeling Meiosis with Crossing Over;7. Build a pair of replicated, homologous chromosomes. 10 beads should be;used to create each individual sister chromatid (20 beads per;chromosome pair). Two five-holed beads represents the centromere. To;do this...;a. Start with 20 beads of the same color to create your first sister;chromatid pair. Five beads must be snapped together for each of;the four different strands. Two strands create the first chromatid;and two strands create the second chromatid with a 5-holed bead;at the center of each chromatid. This creates an I shape.;b. Connect the I shaped sister chromatids by the 5-holed beads to;create an X shape.;2013 eScience Labs;LLC.;All Rights Reserved;c. Repeat this process using 20 new beads (of a different color) to;create the second sister chromatid pair.;8. Assemble a second pair of replicated sister chromatids, this time using 12;beads, instead of 20, per pair (six beads per each complete sister;chromatid strand). Snap each of the four pieces into two five-holed beads;to complete the set up.;9. Pair up the homologous chromosomes created in Step 7 and 8.;10. SIMULATE CROSSING OVER. To do this, bring the two homologous pairs;of sister chromatids together (creating the chiasma) and exchange an;equal number of beads between the two. This will result in chromatids of;the same original length, there will now be new combinations of chromatid;colors.;11. Configure the chromosomes as they would appear in each of the stages of;meiotic division (prophase I and II, metaphase I and II, anaphase I and II;telophase I and II, and cytokinesis).;12. Diagram the corresponding images for each stage in the section titled;Trial 2 - Meiotic Division Beads Diagram. Be sure to indicate the number;of chromosomes present in each cell for each phase. Also, indicate how;the crossing over affected the genetic content in the gametes from Part1;versus Part 2.;Trial 2 - Meiotic Division Beads Diagram;Prophase I;Metaphase I;Anaphase I;Telophase I;2013 eScience Labs;LLC.;All Rights Reserved;Prophase II;Metaphase II;Anaphase II;Telophase II;Cytokinesis;Post-Lab Questions;1. In this experiment, how many chromosomes were present when meiosis I;started?;2. In this experiment, how many nuclei are present at the end of meiosis II?;How many chromosomes are in each?;2013 eScience Labs;LLC.;All Rights Reserved;3. What is the ploidy of the DNA at the end of meiosis I? What about at the;end of meiosis II?;4. How are meiosis I and meiosis II different? List two reasons.;5. Why do you use non-sister chromatids to demonstrate crossing over?;6. What combinations of alleles could result from a crossover between BD;and bd chromosomes?;7. Identify two ways that meiosis contributes to genetic recombination.;8. Why is it necessary to reduce the number of chromosomes in gametes;but not in other cells?;9. Blue whales have 44 chromosomes in every cell. Determine how many;chromosomes you would expect to find in the following;Sperm Cell;Egg Cell;Daughter Cell from Mitosis;Daughter Cell from Meiosis II;2013 eScience Labs;LLC.;All Rights Reserved;10. Research and find a disease that is caused by chromosomal mutations.;When does the mutation occur? What chromosomes are affected? What;are the consequences?;11. Diagram what would happen if sexual reproduction took place for four;generations using diploid (2n) cells.

 

Paper#15080 | Written in 18-Jul-2015

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