Biology Mitosis Lab

1242 Words5 Pages
AP BIOLOGY- Mitosis and Meiosis Cell Division Lab Part 1-MITOSIS summary: In this experiment first the stages of an onion cell undergoing mitosis are going to be observed and every stage is going to be detected and drawn on paper. A brief description to what is going on should be attached to the pictures. This is important to understand the basics of cell division which is necessary growth,repair and asexual reproduction. Second the number of cells undergoing each phase is going to be counted to figure out in which phase the cell remains the most. If interphase is the stage in which the cell grows and prepares for cell division then the…show more content…
Later on a male and female haploid cell will join to form a diploid cell with the right number of chromosomes. Meiosis consists of one DNA replication and two nuclear divisions resulting in 4 daughter cells. The process which provides for genetic variation is crossing over. Crossing over occurs in the early stages when homologous chromosomes move together so that their chromatids form a tetrad. This is called synapsis and allows for the exchange of chromosome sections. In our case the crossing overs will result in different colorings of the ascospores of the S. fimicoli. Materials: -Microscope -S.fimicola meiosis cards Procedure: 1-Study the different phases of meiosis on the cards. 2-Notice the difference between ascospores with sequences of 4’s and 2’s. 3-Count the amount of different sequences present. 4-From the data you gathered calculate the percentage of asci showing crossover. Analysis: Out of a total from 26 sequences only 6 were made up of 4‘s while 20 were composed of different structures of 2‘s. This tells us that 77% of the asci showed crossing over while 23% did not. Conclusion: Our hypothesis that if meiosis is present the new formed asci will have different colors was supported by the outcome of our observations. The fact that different sequences of 2’s emerged from the first pattern of 4’s is prove that crossing over took place. Genetic
Open Document