distilled water watch glass forceps root tip of onion or garlic microscope and light source. You are required to prepare a microscope slide of the meristem tissue from an onion root. You will add a stain to the material which allows you to see the chromosomes. You will look at the slide under the microscope to identify any cells showing stages of mitosis. You will then calculate the mitotic index. Safety Hydrochloric acid (5 mol dm-3) is corrosive and should be handled with caution. Eye protection must be worn. The beaker must be on a bench mat. Do not carry the beaker with acid in it. N.B. Do not leave root tips for investigation lying about on the bench top prior to staining. Cut your root tip immediately before you put it into the acid. This will stop any reactions and hopefully some cells will be in a stage of division. You should read these instructions carefully before you start work. Making your slide Stand the beaker on a bench mat before adding approx. 10ml of hydrochloric acid (5 mol dm-3) about 2 cm of root tip in the acid and leave for 15 minutes. Set up your microscope while you are waiting. Rinse the root tip in distilled water in the watch glass. Cut off the root tip (1mm) and place on a microscope slide. Cover the section with toluidene blue stain and macerate with the mounted needle to separate the cells. Continue to macerate until the tissue is well broken and the cells are stained dark blue. Add a cover slip and with gentle finger pressure the material and blot at the same time ‘spread’ by using a folded filter paper between finger and slide. Look carefully at all slides for undergoing mitosis. Chromosomes should stain dark blue. Repeat for several fields of view. Record your data in a suitable table. Calculate the mitotic index.
distilled water watch glass forceps root tip of onion or garlic microscope and light source. You are required to prepare a microscope slide of the meristem tissue from an onion root. You will add a stain to the material which allows you to see the chromosomes. You will look at the slide under the microscope to identify any cells showing stages of mitosis. You will then calculate the mitotic index. Safety Hydrochloric acid (5 mol dm-3) is corrosive and should be handled with caution. Eye protection must be worn. The beaker must be on a bench mat. Do not carry the beaker with acid in it. N.B. Do not leave root tips for investigation lying about on the bench top prior to staining. Cut your root tip immediately before you put it into the acid. This will stop any reactions and hopefully some cells will be in a stage of division. You should read these instructions carefully before you start work. Making your slide Stand the beaker on a bench mat before adding approx. 10ml of hydrochloric acid (5 mol dm-3) about 2 cm of root tip in the acid and leave for 15 minutes. Set up your microscope while you are waiting. Rinse the root tip in distilled water in the watch glass. Cut off the root tip (1mm) and place on a microscope slide. Cover the section with toluidene blue stain and macerate with the mounted needle to separate the cells. Continue to macerate until the tissue is well broken and the cells are stained dark blue. Add a cover slip and with gentle finger pressure ‘spread’ the material and blot at the same time by using a folded filter paper between finger and slide. Look carefully at all slides for undergoing mitosis. Chromosomes should stain dark blue. Repeat for several fields of view. Record your data in a suitable table. Calculate the mitotic index.