Mitotic index- 2

Question 1

Mitotic index

Question 2

describe the method used to to prepare stained squash cells from plant root tips and identify the stages of mitosis.

Answer 2

1. get the bottle of Hydrochloric acid from the water bath. 10ml of HCL (1mol dm^3)
2. take the piece of root from the preservative and dip in beaker of water
3. place the piece of root in the acid, return to waterbath and leave for 5 minutes
4. set up your microscope while you are moving
5. Dip the root in the beaker of distilled water and dab on a paper towel
6. cut off the root tip (1+mm) on a microscope slide. repeat so you have at least 2 slides each
7. cover the section with one drop of toluidene blue stain and leave for 2 minutes.
8. Add a cover slip and with gentle thumb pressure ‘ squash’ the material and blot at the same time by using a folded paper towel between thumb and slide.
9. chromosomes should stain blue. repeat for several fields of view
10. record your data in a suitable table
11. calculate the mitotic index

Question 3

why can we use only 5mm of the root tip

Answer 3

• these are where cells are undergoing mitosis
• 1 layer of cells - allows light to pass through

Question 4

why is the squash put into acid?

Answer 4

Breaks down the cell wall/membrane to allow stain to enter/ kills cells and slows/pauses mitosis

Question 5

why do you press down firmly on the cover slip?

Answer 5

to get a thin layer of cells so light can pass through

Question 6

why do we use a stain/ why is the stain specific?

Answer 6

will stain chromosomes/ chromatin to see the stages of mitosis

Question 7

why do you use a mounted needle?

Answer 7

to lower the slip and prevent air bubbles under the cover slip

Question 8

What is the Mitotic index?

Answer 8

Mitotic index - (percentage of cells in mitosis at any time) provides a measure of the capacity of cells to divide and the rate of cell division.

Question 9

What equation can we use to calculate the mitotic index?

Answer 9

mitotic index = number of dividing cells/ total number of cells

Question 10

what can the mitotic index be used for?

Answer 10

it is used to identify the sites of growth within a tissue and to determine which cell types are dividing. it also functions as an important prognostic tool for predicting the response of cancer cells to chemotherapy

Question 11

why can a mitotic index be used to identify cancer?

Answer 11

an elevated mitotic index indicates more cells are dividing. In cancer cells, the mitotic index may be elevated compared to normal growth of tissues and cellular repair of the site of injury.

Question 12

Done