A. Title

Observation of Mitosis Phase and Chromosome Position in Allium cepa L.

B. PRACTICAL OBJECTIVES

At the end of this practicum, students are expected to be able to:

1. Recognize the phases of mitosis by observing the position of chromosomes.

2. Understand the stages in making squash method preparations used in microscopic observations.

C. TOOLS AND MATERIALS 

a). Tools

b). Material

D. WORK PROCEDURES

E. OBSERVATION RESULTS

F. DISCUSSION RESULTS

  In the 3rd practicum conducted on Wednesday, October 2, 2024, we conducted a mitosis observation practicum on Allium cepa L. In this practicum, the practicum participants were expected to be able to see the stages of mitosis and see the location of the chromosomes. However, in this practicum, our group was only able to see two of the four stages of mitosis. Namely in the prophase and telophase stages, we could not see all the stages of mitosis because there were several factors that made this practicum not go well.

  At the beginning of the practicum, the practicum participants were asked to prepare the tools and materials that had been ordered by the laboratory assistant, then the practicum participants were asked to sterilize the tools that would be used before placing the samples in the tools that had been provided. The first step we took was to place the onion bulbs in a petri dish filled with water until the roots grew. Cut the tip of the root that had grown with a razor, take the white part then place it in a watch glass and add 70% alcohol and let it soak for 2 minutes. After 2 minutes, the 70% alcohol was sucked up with blotting paper, then soak the roots in the H2O2 solution for 5 minutes. Then take the onion root pieces from the watch glass, then cut the tip (root cap) and place it on the object glass. The next step is to drip it with acetocarmine solution, then chop it using a rusty cutter, then cover it with a cover glass. Then grind it with your thumb or a blunt pencil tip. The preparation was passed over a spirit lamp. Finally, observe the stages of mitosis division under a microscope.

  In the end, our group only got the results of two of the four stages of mitosis, namely the prophase stage, which is the longest and most energy-consuming phase of mitosis. The events that occur during prophase are as follows: Chromatin threads become chromosomes, then the chromosomes double into two chromatids but are still attached to one centromere. and the second is the telophase stage. At this stage, we have entered the final stage of mitosis. At this stage, the chromosomes have arrived at their respective poles. The spindle threads begin to disappear and the nuclear membrane also begins to appear between the two separate groups of chromosomes.

DOCUMENTATION

Observation process under a microscope

Drying onion root tissue samples to make them easier to separate or flatten when making microscopic preparations.

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