Hi guys! Welcome to the first biology post, I hope you are as excited as I am.
Today I decided that it would be interesting to find out more about investigating mitosis in a garlic root tip squash. Talking about what chromosomes do during mitosis is interesting, but being able to see it adds more excitement. Just to warn you, this practical could be pretty disappointing as it doesn’t always work and sometimes it’s hard to see all the phases that are happening during mitosis.
Let’s figure out what mitosis is first. Mitosis is the term used to describe the entire process of cell division in eukaryotic cells. It actually refers to nuclear division. It’s important because we use it for growth, replacement and repair of tissues in multicellular organisms such as animals, plants and fungi. Mitosis consist of 4 stages – Prophase, Metaphase, Anaphase and Telophase. Sounds scary and complicated, right? Don’t worry, it all sounds scary at the start but when you get a hang of it, you are ready to go.
So… what about the actual practical? Your garlic roots need to be prepared 1-10 days in advance of the practical. You will need:
- Water bath at 60 °C
- Hydrochloric acid
- Watch glass (or small dish)
- Mounting needle
- Microscope slide
- Paper towels
OH! Before we start don’t forget about health and safety! Take care with ethanoic alcohol as it is corrosive, hot hydrochloric acid, and with the stain. Wear eye protection when handling these as you don’t want them getting into your eyes. Carry scalpels with care – hold them on a tile as you walk around the laboratory.
To clearly observe the different phases of mitosis, the root tissues must be well fragmented, otherwise each cell will remain attached to the others obstructing all observations. You want to cut off 1-2 cm of the root tips. Put in a small volume of ethanoic acid on a watch glass (or other shallow dish) for 10 minutes.
Meanwhile, heat 10-25 cm³ of hydrochloric acid. Take the root tips out and wash them in cold water for 5 minutes, then dry them. After you have done this use your mounted needle to transfer the root tips into the hydrochloric acid and leave them for another 5 minutes. Hydrochloric acid will weaken and even remove the bonds between the cells so the tissues could be separated into small fragments. Wash the root tips again in the cold water for 5 minutes. Now you are ready to transfer your root tips by using a mounted needle onto the slide. Add a small drop of stain and leave for 2 minutes. The stain will increase the contrast so the chromosomes will become visible.
Break up the tissue and put a cover slip and you are ready to go! Put your slide under the microscope and look for the chromosomes within the cell that are actively dividing.
I hope you enjoyed learning about this practical as well as understanding mitosis and how chromosomes work.
I have included some images for you to have a look at!