Question

Prepare a temporary slide of onion root tip and study at least two mitotic stages.

Answer 1

Answer:

stages of mitotic cell division is karyokenesis ( prophase,metaphase , anaphase , telophase) and cytokinesis)

Explanation:

1. prophase :

in prophase , condensation of basically thin thread like chromosomes starts . due to this , they become short and thick and they start to appear along with their pairs of sister chromatids .

centrioles duplicate and each centriole moves to opposite poles of the cells .

nuclear membrane and nucleolus start to disappear.

2. metaphase:

nuclear membrane completely disappears in metaphase .

chromosomes complete their condensation and become clearly visible along with their sister chromatids .

all chromosomes are arranged parallel to equatorial plane( central plane ) of the cell.

special type of flexible protein fibres ( spindle fibres ) are formed between centromere of each chromosome and both centrioles.

onoions are in the phase of division hence all the stages can be clearly seen.

the stain used for mounting of onion cells is acetocarmine.

Answer 2

Temporary slide of onion root tip and mitotic stages

Explanation:

Preparation of temporary slide of onion root tip:

Materials required:onion,acetoalcohol,water N/10 HCl,acetocarmine,slides,coverslip,forceps,blade,

Procedure:

1. Cut root tips from a freshly grown roots of onion
2. Keep them in a watch glass containing water
3. Place the root tips in a tube containing aceto alcohol with the help of forceps
4. Keep them submerged for a day
5. Next day take a root tip, place it on a glass slide and put a drop of N/10 HCl
6. After that add 2-3 drops of acetocarmine stain on it
7. Use a burner to warm it up(do not burn)
8. Cut the stained portion of the root with the help of a blade and place it on a fresh slide
9. Put a drop water on it
10. Place coverslip on it with the help of a needle
11. Tap a little on the coverslip so that the meristematic tissue is compressed
12. Slide prepared can be observed using a microscope

       Mitotic stages observed are:

• Prophase:nuclear envelope breaks,chromosomes start to coil in the centre

• Metaphase:is the middle stage,all the chromosomes line up at the metaphasic plate of the cell
• Anaphase:Spindle fibres become short,chromosomes are pulled apart to the two opposite poles
• Telophase:the final stage of mitosis,nuclear envelope is reformed,new cell wallis established and two daughter cells are formed