Observing Mitosis in Root Tips - A level biology required practical activity. Make sure you know how to calculate mitotic index. The notes towards the end of the clip explain this.
Hello Ma'am , actually i have one problem during squashing the root tips. the stain is moving out of the cells and i can't see any mitotic phase. please give me some suggestion.
Is the acetic acid stain necessary or will other stains work? I'm struggling to find it. If the acetic acid is part of the process, is it stronger than 5%? That's the strength of off the shelf vinegar.
You can use a stain called Toluidine blue but you do need a strong acid. Usually 5 molar HCl. You will only be able to get these from a scientific suppliers. I have to warn you that it is difficult to get good slides showing all stages of the cell cycle. So I wouldn’t bother with this if not absolutely necessary. You can buy ready prepared slides and there are good images on the internet.
Seeing images on the internet or slides prepared by someone else is not even remotely the same experience! We'll keep trying. I can make 5 molar HCl. That's easy enough. This afternoon we tried using Methylene blue and Carbol fuchsin with 1 molar HCl (that's all I had on hand). We didn't have much luck. I'll try some stronger HCl next time. What is the HCl doing to the cells? Is it breaking apart the layers?
@@biologypracticalsandrevisi8066 Thank you. We will experiment more. I'll try to get some toluidine blue. This is a really fascinating project. Now I'm excited to try out some of your other projects next. :-)
HCL quickly denatures any proteins including enzymes. It quickly stops cellular processes and kills cells halting the process of mitosis immediately so that cells in different stages of the cell cycle can be seen.
Thank you for the detailed reply! Extremely helpful. I have another question. I've seen people adding ethanoic acid on the slide before they place the cut root tips on it. Is this for cleaning the slide or does it serve a completely different purpose? Thanks again! This was a very useful video and it's helping me for my IB Bio IA.
Acetic acid has very low pH, which weakens hydrogen and ionic bonds. In young cell walls, pectins are largely acidic and then prone to establish electrostatic interactions with cellulose and hemicuellulose. In older tissues pectins are methyl-esterified -- more hydrophobic -- and harden at acid pH. Chromatin behaves roughly the same way. Interactions between histones and DNA are mostly electrostatic, so weaken by pH lowering. Weakened interactions between histones and DNA result in softer chromosomes that can be easily squashed Hope I am not that late lol
