======Onion Root Tip Mitosis======


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**Alternative titles:** Observing Stages of Mitosis
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====Summary====                   
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====Procedure====  
  - Grow onion bulbs in water until new root tips develop (4–6 days).  
  - Collect about 3 cm of young root tips and place them in aceto-alcohol fixative (3:1 ethanol and glacial acetic acid) for 24 hours.  
  - Transfer a root tip to a clean slide and add 0.1N HCl followed by acetocarmine stain.  
  - Gently heat over a burner without drying the stain.  
  - Trim off less-stained portions and retain the well-stained root tip.  
  - Add a drop of water and mount a coverslip.  
  - Tap the coverslip gently to squash the tissue into a thin layer.  
  - Place the slide under the compound microscope and observe the stages of mitosis.



====Links==== 
Mitosis in Onion Root tip Experiment - ThomasTKtungnung: 
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How To: Observe Mitosis in Onion Root Tips - LabXchange: 
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📄 study-of-mitosis-in-onion-root-tip-cells - byjus.com: [[https://byjus.com/biology/study-of-mitosis-in-onion-root-tip-cells/]]\\


====Variations====
  * Use prepared slides of onion root tips if time or equipment is limited.  
  * Compare mitosis in onion root cells with mitosis in animal cells (e.g., whitefish blastula).  
  * Extend the study to include meiosis for comparison.



====Safety Precautions====
  * Handle sharp blades and scalpels carefully.  
  * Use stains (acetocarmine, HCl, aceto-alcohol) cautiously; they can damage skin, clothing, and surfaces.  
  * Heat slides gently to avoid boiling or cracking.  
  * Follow all lab safety rules, including wearing gloves and protective eyewear if required.




====Questions to Consider====
  * Why is mitosis called equational division? (Daughter cells have the same chromosome number as the parent cell.)  
  * Why are onion root tips commonly used to study mitosis? (They have actively dividing meristematic cells and large, visible chromosomes.)  
  * Which stage of mitosis shows the chromosomes most distinctly? (Metaphase, because chromosomes are thick, condensed, and aligned at the equator.)  
  * How can colchicine affect mitosis? (It prevents spindle fiber formation, stopping cells in metaphase.)  
  * How do plant and animal cells differ in spindle fiber origin? (Plant cells form spindle fibers from the cytoplasm; animal cells form them from centrioles.)