Procedure for Staining Root Tips

Preparing the Onion Root Tips Fill two jars with 1.5 cm of fine sand. Label one jar control and the other with your independent variable. Wet sand in IV jar with your IV. Wet the sand in control jar with H2O. Prepare bulbs by cutting off dried roots back to base with razor blade. Insert onions in to sand till they touch bottom of the jar. Store in dark for 1.5 – 2 days

Harvesting the Onion Root Tips Wearing gloves remove bulbs from sand and rinse off sand with H20 Cut off the roots from each bulb using razor blade. Place in Carnoy’s fixative for 24 hours

Harvesting the Onion Root Tips Remove tips from Carnoy’s fixative. Place tips in plate with 70% ethanol Place in ethanol and store covered at 4°C Preparing chromosome squashes. Place Root tip in 6 M HCl for 4 minutes Transfer to Carnoy’s fixative for 4 minutes Remove slide form Coplin Jar with 70% ethanol, dry with kim wipe, and label slide Place onion tip on slide, cut off distal (far away from root tip) portion of the tip. Try to keep only the tip. Cover with 1 drop carbol fuschin stain for 2 minutes Blot off excess stain and cover tip with 1-2 drops H2O Place cover slip over tip . Press down with eraser end of a pencil