mitosis practical Flashcards
(8 cards)
detailed method
- cut off root tip off onion/garlic and add to beaker of 10ml hydrochloric acid
- leave in for 10 mins
- rinse the root tip in distilled water
- place specimen on microscope slide
- cover specimen with toluidene bleu stain and macerate with mounted needle to separate cells
- add cover slip and spread material gently
- look through microscope
- chromosomes should stain dark blue
- take a photo of sample
- calculate mitotic index
why are you told to observe cells that are found at or just behind the root tip called the meristem
most ideal area to look for mitosis, meristem cells are undifferentiated, and constantly dividing, making them ideal to observe.
cells in meristem are totipotent
explain why cells may appear elongated with no visible chromosomes if they are taken too far along the root
in the region of cell elongation, they are increasing in size but not dividing
why use HCL
-HCL quickly denatured any protein including enzymes
- it quickly stops cellular processes
- kills cells halting the process immediately so the cells in different stages can be seen
why use toluidine blue
Dye is used for staining of acid rich tissues
As it can be absorbed by nucleic acid
- it increases contrast
- makes chromosomes visible
why is it necessary to spread the material on the slide
cells could overlap each other
stain might not have been dispersed properly
why is it suggested to look at several fields of view
-comparison
-mean of mitotic index
what does diploid number of 16 mean
-8 chromosomes from male
-8 from female