Lab Report ?3 Title:Observing Mitosis By Yerkebulan Yesbolatov Biology course, tutorial group I October 18, 2012 Lab partner: Azhar Zhaisanova Introduction Experiment is intend to show mitotic stage of cell cycle, phases of mitotic stage, to define predominance in the number of each phases over the others, if it is possible. Objectivity of lab is to observe the different phases of mitotic stage of cell cycle, to get skills for special technique( by using orcein ethanoic stain) designed for making slide enable to observe mitotic stage of cell cycle.
The tip of Garlic bulb’s root is suspected to be relevant for that, for observing the cell cycle. Aim To observe cell cycle in definite stage-in this experiment mitosis. To get knowledge of which phase is predominate in cell cycle. Precautions During the procedure it is need to wear eye protection cause hydrochloric acid is irritant It is necessary to wear gloves and coat – Toluidine blue is had ability to ingrain. Don’t ingest- it is harmful. It is necessary to wear goggles and avoiding of content with orsein ethanoic stain, cause it corrosive, irritant, causing burns, has ability to irritate by vapour.
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In case of making contact immediately necessary to wash with water for 10 minutes. It is necessary to wear eye protection and avoid a skin contact, cause Acetic alcohol is corrosive and highly flammable Methods and Materials First method of staining is cancelled. Second method with 1-st step was provided in advance. First, several root tips was cut off, added to watch glass with acetic alcohol(2cm3) for 10 minutes. Then, specimens transferred to second glass, which contain 5cm3 ice cold water,4-5 minutes are needed to wait after that. Later on specimens, dried off with filter paper.
Next step, in order to haven’t damage a specimen ,it was poured with pre-heated hydrochloric acid rather than putting the pattern to test tube and vice versa till 5 minutes. Next step is to repeat step with acetic acid (2cm3) for 10 minutes in a watch glass. After 10 minutes, specimen (one of several) was put to glass slide then poured with 1-2 drops of stain called acetic orcein stain, it should cover whole surface of pattern. Note that to stain the wall would be better to leave specimen in a dye more than 2 minutes. Finally, specimen is covered with coverslip and pushed under the filter paper, put to microscope and observed. Result
Question 1 is in separate page Question 2 Number of cells viewed under visible area x400. 43 cells 43×4=172 Table of numbers of cells at field of view Total number of cells| Names of mitosis phases| ? in each stage| 172| Interphase| 138| | Prophase| 28| | Metophase| 3| | Anaphase| 2| | Telephase| 1| Question 3. Percentage in each stage of mitosis Interphase =138172×100%= 80. 232% Prophase =28172×100%=16. 279% Metophase =3172×100%=1. 744% Anaphase =2172×100%=1. 162% Telephase =1172×100%=0. 581% Ranking of stages of cell cycle Interpase>prophase>metaphase>anaphase>telephase As it said, preparation freezed at one time.
Most of cells, about 90% of cell and consequently 90% cycle cell spent in interphase, it is proved by findings. Roughly 20 percent, approximately quarter of interphase are taken by prophase, metaphase, anaphase, telephase. Question 4 Mitotic index Mitotic index=28+3+2+1172=34172= 0. 197 Mitotic index enable to find a tendency to grow of cells. It is mean that how cell is divide, at which rate it is reproduces. Question 5 Reliability and validity If centromeres of chromosomes are draw up at equator, we definitely could say it is metaphase, if we see sister chromatids at inverse poles we could say definitely say as it anaphase.
A lot of cells are there with round nucleuses that is why it is – prophases. Telephase is differ by starting of dividing of cells. In interphase cells are as they are swallowed, e. c become bigger. Question 6 Safety precautions Wear goggles to avoid contact with orsein ethanoic stain is corrosive, has ability to irritate by vapour Wear gloves – acetic alcohol is corrosive and highly flammable. Question 7 Treatment with hydrochloric acid It enable to stain the specimen of root tip. It can help to break the hydrogen bonds contain in it. Question 8 Reason Cells are in phase of telephase of mitosis or meiosis stage could start.
Discussion There was cells with purple chromosomes on a pink background. There was drawn the each phases of mitosis to make easier the differentiation of phases cause is sometimes difficult to differ. At the beginning, when final stage of slide preparation was done, there was problem, three times with its observing-the image wasn’t enough pure to see a cells in mitosis stage. Cause could be wrong decay of specimen during the pressing. It should be taken into care that pressing of stained specimen should be strong to make image more clear and transparent. To define the number of cells visible t point of view (image which enable objective to see during reviewing without changing the position) of microscope it was calculated the quarter of circle row by row cause cells are not same, so rows are not same. Defining of microscope’s point of view is necessary for further calculating the percentage of each phase of mitosis. So, quarter of visible cells was equal to 43. These cells was multiplied to four. To tell every phase of mitosis:138 of interphases,28 prophases,3 metaphases,2 anaphases, 1 telephase. As shown in calculations, abundance are correspond as follows: Interphase=80. 32; Prophase=16. 279% ;Metophase=1. 744% ; Anaphase=1. 162% Telephase=0. 581% ; As we see interphase is equal to roughly 80%,however in book there was claim that interphase spend 90% of cell cycle. From this point could be proposed that root grown in favorable condition as it is known that in interphase cell is phase of rash activity, cell copy own DNA and energy is create for further mitosis. As shown in mitotic index formula, numerator contain only cells with visible chromosomes, that is mean that interphase is not taken to consideration.
Mitotic index enable to find a tendency to grow of cells. It is mean that how cell is divide, at which rate it is reproduces. In this experiment mitotic index is equal to 0. 197 Due to fact that there was not mitotic index scale it is difficult to say anything about tendency. In oncology(study of tuour cells) mitotic index has its special calibration, special standards. Error analysis Probability of error may cause the fact that in some case there was nuclear membrane without changing, but nucleoli had already vanished.
So, there was probability of error to take to consideration the stage as a interphase and as prophase. Conclusion It is proved that is visible the dividing (in cell cycle) cells with method using a orcein ethanoic stain. Most of time cells a spend for interphase. This is proved by experiment result-80% of cells was at interphase stage. Most of all it is possible or easy to define exactly the stages such as anaphase, metaphase cause it definite characters are allow to do so. The late prophase and beginning of telephase is difficult to differentiate cause processes happened in them are opposite to each other.