Muhammad Taha Saeed 28100487 Section 6 Observing Mitosis in Cells of Onion Roots Objective: To observe and understand the stages of mitosis in onion root tip cells using a microscope. To learn the preparation and staining of slides Introduction: Mitosis is a process of cell division that creates two identical daughter cells from a single parent cell. It ensures proper growth, development, and tissue repair in multicellular organisms. The onion root tip is commonly used to study mitosis due to its active cell division. By staining the cells, we can make chromosomes visible and observe the distinct stages of mitosis under a microscope. Materials Required: - Fresh onion root tips - 1M HCl (hydrochloric acid) - Aceto-orcein stain - Compound microscope - Microscope slides and coverslips - Razor blade - Micropipettes with tips - Filter paper & Tissue paper - Forceps Method: 1. Collect the Onion Root Tips: - Using a sharp blade, cut 1 cm from the terminal end of the onion root tip. 2. Prepare the Tissue: - Place a drop of 1M HCl on a clean microscope slide. - Transfer the root tip onto the HCl drop with forceps. - Let the root tip sit in the HCl for 2-3 minutes to soften it. 3. Stain the Cells: - Move the softened root tip to a new slide with a drop of aceto-orcein stain. - Chop the root tip into small pieces using a blade. - Leave the stained root tip for 3-5 minutes to enhance visibility of chromosomes. 4. Prepare the Slide: - Place a coverslip on top of the stained root tip. - Cover the coverslip with tissue paper and press gently with your thumb to spread the cells evenly 5. Examine Under the Microscope: - Place the slide under the compound microscope. - Start with the 10X lens to locate cells, then switch to the 40X lens for a closer view. - Adjust the focus to clearly observe cells at different stages of mitosis. Observation: Here are the observations made during the experiment: 1. Interphase: Most cells were in this stage, showing a nucleus with dispersed chromatin. 2. Prophase: Chromosomes started condensing into thread-like structures; the nuclear membrane began disappearing. 3. Metaphase: Chromosomes aligned in the center of the cell (metaphase plate), looking thick and distinct. 4. Anaphase: Chromatids were pulled apart to opposite poles, forming a V shape. 5. Telophase: Chromosomes decondensed, and new nuclear membranes formed around each set. Discussion: This activity successfully demonstrated the stages of mitosis in onion root tip cells. The use of aceto-orcein stain made the chromosomes highly visible. Proper staining techniques were critical for obtaining clear images. Studying mitosis is essential for understanding cellular growth and development. It also has applications in medical research, particularly in understanding uncontrolled cell division in cancer.
