Observing Mitosis Flashcards
What were chromosomes stained with
orcein ethanoic stain
What equipment is required (12)
- Garlic roots
- sharp knife
- 1M hydrochloric acid
- Ethanoic alcohol
- Orcein ethanoic stain
- ice-cold distilled water
- water bath @ 60 ̊C, 2 watch glasses
- test tube, 2 pipettes
- microscope slides
- forceps, mounted needle
- filter paper
- microscope with mag x100 & x400
Outline the method
place test tube of 2cn3 1M HCl into 60 ̊C waterbath. Cut off 1-2cm of root tip from garlic root. Put in watch glass containing 2cm3 of acetic alcohol for at least 12 mins. Remove then place into another watch glass containing 5cm3 ice cold distilled water. Leave for 4-5 mins, then remove and dry. Place tips into heated HCl for 5mins then repeat process again by placing tips back into acetic alcohol etc. Tips will be very fragile at this point. Transfer 1 tip to microscope slide, cut 4-5mm from growing tip (site of mitosis) and keep the tip. Gently break up (macerate) with mounted needle, add 1 small drop of orcein ethanoic stain and leave for 2 mins. Add coverslip and blot with filter paper. View under microscope and identify the stages of mitosis.
What are some possible evaluation issues (3)
- Resolution of microscope
- Human error in counting numbers of cells
- Enough time in the solutions to enable successful maceration or staining.
