The root tip is heated with acid to break up the tissues into individual cells. The cellulose walls of plant cells are held together by pectins such as calcium pectate. Treatment with hydrochloric acid breaks this down.
What is the significance of hydrochloric acid in cell staining?
The links between the cellulose walls of plant cells are broken down by the treatment with hydrochloric acid. This ensures that the stain can penetrate the cells and allows the tissue to be squashed out one cell thick. The mitotic index is calculated like this:
How do you clean root tips with ethanoic acid?
Put in a small volume of ethanoic acid on a watchglass (or other shallow dish) for 10 minutes. b Meanwhile, heat 10-25 cm 3 of 1 M hydrochloric acid to 60 °C in a water bath. c Wash the root tips in cold water for 4-5 minutes and dry on filter paper.
How do you clean the root tips of a tomato plant?
a Cut off 1-2 cm of the root tips. Put in a small volume of ethanoic acid on a watchglass (or other shallow dish) for 10 minutes. b Meanwhile, heat 10-25 cm 3 of 1 M hydrochloric acid to 60 °C in a water bath. c Wash the root tips in cold water for 4-5 minutes and dry on filter paper.
Can I use ethanol Ida instead of methanol for root tips?
You can use ethanol IDA or 95% ethanol instead (Hazcard 40 A – highly flammable and harmful due to the presence of methanol), but chromosomes may not be as clearly defined. Root tips can be kept in this fluid for several months.
Why is hydrochloric acid used in the root squash?
The links between the cellulose walls of plant cells are broken down by the treatment with hydrochloric acid. This ensures that the stain can penetrate the cells and allows the tissue to be squashed out one cell thick.
What is the purpose of hydrochloric acid when preparing onion root tips?
Place the tip on a slide and add two drops of 0.5M hydochloric acid (HCl) to the tip. Let the root tip soak in the HCl for 10 minutes. (The HCl helps break apart the tissue so the cells can be seen better.)
Why are the root tips warmed in 1.0 M HCl before squashing and staining?
Treatment with acid and heat is used to break up the cellulose cell wall allowing stain to permeate the tissue and makes it easier to squash the tissue on a microscope slide.
Why do we use Acetocarmine for staining the root tips?
Acetocarmine is a DNA specific stain like feulgen stain, so the super coiled chromosomes during different stages of mitosis present in the onion root tip cells can be visualized perfectly by treating with this stain.
Why root tips should be fixed in the morning?
Root tips are fixed during morning hours to study mitosis in them. The root tips contain actively dividing meristematic cells so they can be used to view the chromosomes at different stages of cell division. Mitosis is affected by temperature and time.
Why does pH affect mitotic index?
If the pH of the surrounding is close to pH 5.5 to pH 6.5, the plant will have the highest mitosis(growth) rate, resulting in aheavier weight and a longer root. However, in pH 10 groups, the mitosis(growth) rate will be slower, resulting in a lighter weight and a shorter root.
Why are root tips squashed?
The root tip is squashed so you have a thin layer of cells through which the stain can easily penetrate and light can easily pass through.
Which stain is used in squash preparation?
Root meristems of Sonoran Desert succulents were used to illustrate the method. Fixed root tips were stained by Feulgen and squashes were prepared in a 1:2 mixture of solution A (45% acetic acid) and solution B (3:1 mixture of 0.5% gelatin in water:0.02% of alcian blue 8GX in 45% acetic acid).
Why do you need to squash the onion root tip?
An onion root tip is a rapidly growing part of the onion and thus many cells will be in different stages of mitosis. The onion root tips can be prepared and squashed in a way that allows them to be flattened on a microscopic slide, so that the chromosomes of individual cells can be observed easily.
Why is Acetocarmine basic?
What is Acetocarmine. Carmine is a basic dye prepared from an insect known as Coccus cacti. Acetocarmine is produced by mixing carmine with glacial acetic acid. It is a DNA-specific stain used for the visualization of super-coiled chromosomes during the different stages of mitosis.
Why is Acetocarmine used?
The stain used for dying the chromosome is acetocarmine. This stain is a DNA-specific stain and is used when the study of different mitotic stages is required. To stain chromosomes first acetocarmine dye is prepared using the carmine.
Why acetic acid is used in Acetocarmine?
Squashing the stained specimens in 45% acetic acid increases the contrast between stained chromosomes and destained cytoplasm. The advantages of this method are its simple procedure and applicability to both somatic and meiotic chromosomes.
How do you preserve onion root tips for mitosis?
0:515:24Mitosis in Onion Root tip Experiment - YouTubeYouTubeStart of suggested clipEnd of suggested clipCut out one centimeter of root tips and transfer them into a tiny vial containing car noise fixativeMoreCut out one centimeter of root tips and transfer them into a tiny vial containing car noise fixative fluid car noise fluid fixes the DNA of the root tip cells. Leave the roots in the fixative.
What effect will maceration and pressing the slide preparation have on the dividing cells?
What effect will maceration and pressing the slide preparation have on the dividing cells? single layer. This makes it easier to see the chromosomes and to identify the stages of division.
How do you identify metaphase stage?
Metaphase During metaphase, the nucleus dissolves and the cell's chromosomes condense and move together, aligning in the center of the dividing cell. At this stage, the chromosomes are distinguishable when viewed through a microscope.
How do you calculate mitotic index?
Worked ExampleMitotic index = number of cells with visible chromosomes ÷ total number of cells.Mitotic index = (prophase + metaphase + anaphase + telophase) ÷ total number of cells.Mitotic index = (14 + 5 + 3 + 6) ÷ (36 + 14 + 5 + 3 + 6)Mitotic index = 28 ÷ 64.Mitotic index = 0.44.