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Mitosis + Meiosis LAB

Mitosis + Meiosis LAB. Mitosis Lab—Counting cells in an onion root (Kingdom Plantae). Why are we looking at the tip?. Magnify and calculate % of cells in phase X 1,440 minutes=___min spent in each phase Please make a hypothesis.

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Mitosis + Meiosis LAB

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  1. Mitosis + Meiosis LAB

  2. Mitosis Lab—Counting cells in an onion root (Kingdom Plantae). Why are we looking at the tip? • Magnify and calculate • % of cells in phase X 1,440 minutes=___min spent in each phase • Please make a hypothesis

  3. Procedure1. Observe every cell in one high power field of view and determine which phase of the cell cycle it is in. This is best done in pairs. The partner observing the slide calls out the phase of each cell while the other partner records. Then switch so the recorder becomes the observer and vice versa. Count at least two full fields of view. If you have not counted at least 200 cells, then count a third field of view. 2. Record your data in a table

  4. % of cells in phase X 1,440 minutes=___min spent in each phase

  5. Fungus creating spores that are haploid • Kindom Fungi

  6. Crossing over

  7. Sordaria • Four black ascospores in a row next to four tan ascospores in a row indicates that crossing over has NOT occurred. • Any other arrangement of ascospores indicates that crossing over has taken place.

  8. Sordaria—Meiosis Lab • Study this small section of a slide of Sordaria to determine if crossing over has occurred in the asci designated by an X. • If the ascospores are arranged 4 dark/4 light, count the ascus as "No crossing over." If the arrangement of ascospores is in any other combination, count it as "Crossing over." (Keep track of your counts with paper and pencil.) • In this exercise, we are interested only in asci that form when mating occurs between the black-spore strain and the tan-spore strain, so ignore any asci that have all black spores or all tan spores. Occasionally the asci rupture and spores escape. You can see them here as individual spores not in one of the possible arrangements, so don't include them in your count.

  9. For your Meiosis Discussion • What is the lifecycle of a fungus? • What is crossing over? • Why was there a high rate of crossing over? For your MITOSIS Discussion • Cells were mostly in ___phase. WHY?

  10. 1. In the photo, how many asci marked with an X show no evidence of crossing over? 2. In the photo, how many asci marked with an X show evidence of crossing over? 3.In the photo, what is the total number of asci marked with an X? 4. What is the percent of crossovers? (number of asci with crossovers divided by total number of asci multiplied by 100)

  11. Sordaria Answers 1) 4 2) 7 3) 11 4) 63.6%

  12. Cytokinesis in plants and animals. How do they differ? How are proteins involved?

  13. What did you discover?

  14. Fun fact: Metaphase is the longest phase in mitosis

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