biology
Name___________________________________ Score________________
Section___________________________________ Date_________________
EXERCISE NO. 1a
MITOSIS
OBJECTIVES
The students should be able to: 1. identify the different steps involved in mitosis and meiosis;
2. describe the behavior of the chromosomes during each stage of cell division;
3. identify specific events in mitosis and meiosis that allow the inheritance of traits and generation of variation.
MATERIALS
A. Microscopic Examination
Compound microscope cover slip Prepared slides of onion root tip (Allium cepa) 45% HAc Onion bulb alcohol lamp Farmer’s Solution (acetic acid-ethanol=1:3) 70% ethanol bent needle acetocarmine stain (2%) glass slide
PROCEDURE
A. Microscopic Examination
1. Fresh Specimens
Preliminary Preparation (2 days before laboratory period)
a. Grow onion root tips in tap water for days to a length of 2-3 cm.
b. Cut about 1 cm of the root tips and fix in Farmer’s solution for 48 hrs.
c. Transfer root tips to a vial containing 70% ethanol and store at 4oC.
d. Bring to class for examination.
Preparation of Temporary Mounts
e. Place the root tips in the middle of a glass slide and squash in 45% acetic acid with the use of a bent needle. Add 1 drop of acetocarmine solution. Put a clean cover slip on the smear.
f. Pass slide over the flame of an alcohol lamp for 10s to improve staining. Extreme caution must be observed so that the specimens will not be burned.
g. Examine under LPO, then under HPO. Focus at the region of elongation. Look for dividing cells and make the required sketches. Take pictures for documentation. DO NOT COPY DRAWINGS FROM THE BOOK!!!
h. Destaining can be done using 45% HAc if the cells appear to dark.
i. When cells are properly stained, seal the edges with paraffin balsam.
Sketches :
A. Microscopic Examination of onion root tip chromosomes
Section___________________________________ Date_________________
EXERCISE NO. 1a
MITOSIS
OBJECTIVES
The students should be able to: 1. identify the different steps involved in mitosis and meiosis;
2. describe the behavior of the chromosomes during each stage of cell division;
3. identify specific events in mitosis and meiosis that allow the inheritance of traits and generation of variation.
MATERIALS
A. Microscopic Examination
Compound microscope cover slip Prepared slides of onion root tip (Allium cepa) 45% HAc Onion bulb alcohol lamp Farmer’s Solution (acetic acid-ethanol=1:3) 70% ethanol bent needle acetocarmine stain (2%) glass slide
PROCEDURE
A. Microscopic Examination
1. Fresh Specimens
Preliminary Preparation (2 days before laboratory period)
a. Grow onion root tips in tap water for days to a length of 2-3 cm.
b. Cut about 1 cm of the root tips and fix in Farmer’s solution for 48 hrs.
c. Transfer root tips to a vial containing 70% ethanol and store at 4oC.
d. Bring to class for examination.
Preparation of Temporary Mounts
e. Place the root tips in the middle of a glass slide and squash in 45% acetic acid with the use of a bent needle. Add 1 drop of acetocarmine solution. Put a clean cover slip on the smear.
f. Pass slide over the flame of an alcohol lamp for 10s to improve staining. Extreme caution must be observed so that the specimens will not be burned.
g. Examine under LPO, then under HPO. Focus at the region of elongation. Look for dividing cells and make the required sketches. Take pictures for documentation. DO NOT COPY DRAWINGS FROM THE BOOK!!!
h. Destaining can be done using 45% HAc if the cells appear to dark.
i. When cells are properly stained, seal the edges with paraffin balsam.
Sketches :
A. Microscopic Examination of onion root tip chromosomes
References: