MADE BY: BY: PRADEEP SINGH CLASS:: XII CLASS
Objective:
Student Observes The Cells O An On!"n R""t T!# And C"$#%res The &u%nt!t' O Cells In The D!(erent Ph%ses O M!t"s!s)
The stages of mitosis
Prophase:-During prophase, the chromosomes supercoil and the fibers of the spindle apparatus begin to form between centrosomes located at the pole of the cells. The nuclear membrane also disintegrates at this time, freeing the chromosomes into the surrounding cytoplasm.
Prometaphase. During prometaphase, some of the fibers attach to
the centromere of each pair of sister chromatids and they begin to move toward the center of the cell.
Metaphase. At metaphase the chromosomes have come to rest along the center plane of the cell.
Anaphase.
During anaphase, the centromeres split and the sister chromatids begin to migrate toward the opposite poles of the cell.
Telophase. During telophase, the chromosomes at either end of the cell cluster begin to cluster together, which facilitates the formation of a new nuclear membrane. This also is when cytokinesis occurs, leading to two separate cells. One way to identify that telophase has begun is by looking for the formation of the cell plate, the new cell wall forming between the two cells.
Materials: S$%ll
resh "n!"n
S$%ll
*%rs+ ,l%sses+ "r be%-ers
T""th#!.-s Mur!%t!.
%.!d /012 HCl3 "und %t h%rd4%re
st"res S%et' L%te5
,",,les
,l"ves
6"r.e#s
"r t4ee7ers
D!st!lled
4%ter
P!#ette P%#er
"r e'e dr"##er
t"4els
R%7"r bl%de "r s.%l#el
8 needles "r #!ns
1)92 T"lu!d!ne blue %v%!l%ble "nl!ne
M!.r"s."#e sl!des %nd ."versl!#s
D!sse.t!n, $!.r"s."#e "r $%,n!'!n, lens
C"$#"und l!,ht $!.r"s."#e
Experimental Procedure: Create
your hypothesis as to which phase of mitosis you believe will be most prevalent in your sample and why. Base this hypothesis on which phase you believe will take the longest amount of time in the cell. e!t, insert "#$ toothpicks around the sides of the onion and place the onion root side down %stem side up& in a glass or 'ar of water. The bottom of the onion should be submerged in the water. (ait a few days for roots to grow.
Once
there are long roots growing on the onion, remove the onion from the water and use the ra)or blade or scalpel to slice about * mm off the tips of the roots. +lace the root tips into another small beaker or thin#walled glass 'ar. +our muriatic acid into the 'ar with the root tips. (ear hand and eye protection while working with the acid. Allow the root tips to sit in the acid for about - minutes.
se
forceps to remove the root tips from the acid and rinse the acid down the drain with plenty of running water. +lace the root tips on a microscope slide and rinse them several
times with a pipette and distilled water. (ear hand and eye protection during these steps as well.
Carefully
use the ra)or or scalpel to trim the root tips to mm long, keeping the tips. se needles or pins to carefully slice the root tips into or more length#wise sections. Doing this work with a magnifying lens or under a dissecting microscope may be helpful.
se
a pipette to coat the dissected root tips in Toluidine blue. /et sit for minutes. +lace a coverslip on top and pipette distilled water onto the slide. se a paper towel to soak up e!cess dye. se more than one microscope slide for multiple roots, with only about root tips per slide.
+lace
the slide on the microscope. Turn the microscope on and make sure that it is placed on its lowest magnification first. 0ocus the image until you can clearly distinguish the tip of the root. 1ove up slightly from the tip and focus on the area 'ust above root tip where the cells will be replicating. Change the microscope ob'ective to the ne!t highest magnification. 0ocus on the area of cell replication. 2dentify the different stages of mitosis. 2f this is difficult at this magnification, try moving up to the highest magnification. Once you are able to easily identify the stages of mitosis within the area of cell replication, draw a
sketch of each stage that you view. Compare the sketches to internet or te!tbook images of the stages to ensure that you are correctly identifying each stage of mitosis. ow that you are able to easily and correctly identify each stage, begin counting the cells in each stage. 3ou must do this carefully and systematically to avoid counting cells more than once. Try moving from one area of the root tip, down and over to another area. Count many cells in multiple root tips, with a goal of counting at least 4--- cells. Take breaks between root tips if needed to rest your eyes and recheck your sketches. 5ecord the number of cells in each stage with tick marks in a table. 6aving someone help you record the numbers while you count might be helpful. Once
you have counted at least 4--- cells, convert your tick marks to numbers. 7raph your results with a bar graph. Compare your results to your hypothesis and draw conclusions about which stage of mitosis is most common and takes the longest amount of time.
OBSERATION
D!(erent #h%se " "n!"n .ell
Re#resent%t!"n
Des.r!#t!"n
D!%,r%$
s!n,le+ #r"$!nent nu.leus
.hr"$"s"$es v!s!ble
.hr"$"s"$es l!ne u#
.hr"$%t!ds se#%r%te
RES;LT
t4" nu.le! v!s!ble+ .ell s#l!ts
Onion Root Tip – Cell Count
N"4 th%t 4e %re %ble t" !dent!' .ells !n d!(erent st%,es " the .ell .'.le+ n"4 !t !s t!$e t" underst%nd h"4 l"n, % .ell 4!ll tend t" be %t e%.h " these st%,es)
Th!s !s t" ."unt h"4 $%n' .ells !n '"ur r""t t!# s#e.!$en 4ere <r"7en !n t!$e= !n d!(erent st%,es " d!v!s!"n 4hen th!s sl!de 4%s $%de)
Stage of
Total
Mitosis Interphase
Percent Of Cells
4
36
47
2!
6"2#$
3
#
4
2%"%$
2 Prophase
%
Metaphase
6
!
4
!
7"3!$
&naphase
2
3
2
7
3"43$
Telophase
7
!
4
6
7"#4$
Total
%%$
Deter$!n!n, T!$e S#ent In D!(erent Ph%ses O The Cell C'.le Stage of Mitosis
Time Spent
Interphase
4$ hours $ minutes Prophase
$ hours $8 minutes Metaphase
4 hour $9 minutes &naphase
$8 minutes Telophase
4 hour *8 minutes
References: http:;;www.biology.ari)ona.edu;cell
ycle.html http:;;www.marietta.edu;=biol;introlab;Onion>-root
>-mitosis.pdf
http:;;www.biologycorner.com;worksheet;mitosis
