EXPERIMENT 6.2 Objective. To study various stages of mitosis in animal cells (grasshopper) from permanent slide.

                         EXPERIMENT 6.2

Objective. To study various stages of mitosis in animal cells (grasshopper) from permanent slide.

REQUIREMENTS

Permanent slide of mitosis in animal cells, record file, pencil, eraser, sharpner, ruler, a laboratory guide or practical book.

PROCEDURE

1.Place the permanent slide under the microscope.

2.Observe first under the low power of the microscope to locate the dividing cells.

3.Then observe under the high power of microscope to examine different stages of mitosis.

OBSERVATIONS

1.Under high power of the microscope following stages are observed:

Interphase

(i) The cells contain a prominent nucleus with intact nuclear membrane and nucleolus.

(ii) Chromatin material appears in the form of network within the nucleus.

Prophase

(i) The chromatin material shortens and condenses into thread like structures called chromosomes. Each chromosome consists of two chromatids joined at a point called centromere.

(ii) The centriole pair replicate to form two pairs of centrioles, which migrate towards opposite poles.

(iii) Nuclear membrane and nucleolus start disappearing.

Metaphase

(i) A bipolar spindle develops in the cell, with asters made up of centriole pairs forming the poles.

(ii) Chromosomes are arranged at the equator of the spindle.

Anaphase

(i) The sister chromatids of each chromosome separate and appear in V, J, L and I shape towards poles.

5. Telophase

(i) Daughter chromosomes uncoil to form chromatin fibres at the two poles.

(ii) Nuclear membrane and nucleoli are reformed to form daughter nuclei.

(iii) A constriction start developing between the two nuclei.

(iv) The constriction divides the parent cell into two daughter cells.

PRECAUTIONS

1.Use fine adjustment knob, while focussing in high power of the microscope.

2.Objective lens should not touch the slide.