85900

OBSERVING MITOSIS IN ROOT TIPS

Лабораторная работа

Биология и генетика

Nuclear division has 2 forms: mitosis and meiosis (Kent 2000, 74). Mitosis is the process of cell cycle, by which there will be created 2 identical copies of original cell (BBC 2014). This means, the haploid parent cells will produce haploid daughter cells, while the diploid parent cells will produce...

Украинкский

2015-03-31

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Biology Lab Report

OBSERVING MITOSIS IN ROOT TIPS

Completed on 19.10.14

Experiment was performed on 13.10.14

By Kalima Razbek

Group “K”

Lab Partner: Ruslan Nassyrov

  1.  INTRODUCTION

     Nuclear division has 2 forms: mitosis and meiosis (Kent 2000, 74). Mitosis is the process of cell cycle, by which there will be “created 2 identical copies of original cell” (BBC 2014). This means, the haploid parent cells will produce haploid daughter cells, while the diploid parent cells will produce diploid daughter cells: n → n, 2n → 2n (Gregory Ph.D. n.d.). This division is very important in the world of biology, as it is the way of reproduction and growth of cells. Mitosis starts with the stage called interphase, where the replication of DNA, and forming of ATP energy occurs (Kent 2000, 76). There are 3 stages in interphase: G1, S and G2 which are continued by mitosis in its own main 4 stages: prophase, metaphase, anaphase, and telophase (Kent 2000, 76-77). In Prophase “the nucleoli in nucleus disappears” and chromosomes construct in line to get joined to the centrosome (Dawson 2002). Metaphase provides the centrosomes to be aligned to each other and chromatids are applied to the micro tubes for forming the spindle (Dawson 2002). “The paired chromosomes separate” in anaphase, and it ends up with having 2 different cells with finished total set of chromosomes (Dawson 2002). Telophase provides the completed mitosis, where one nucleus has divided into two identical daughter cells; this leads to cytokinesis that forms a cleavage furrow (Dawson 2002).

       So, the aim of this practical is to learn to observe the mitosis in root tips and to study how to use microscopes and to record the results.

       The objectives of this experiment are:

  1.  Be able to better understand the stages and procedure of mitosis in experiment.
  2.  To learn how to prepare the required equipment for the experiment, while remembering about the health and safety.
  3.  To be able to read the results and record them.  

  1.  Materials and Method

  1.  This lab work requires materials as:

Risky Materials:

Danger:

1 M hydrochloric acid

Irritant

Acetic Alcohol

Corrosive and highly flammable

Orcein ethanol stain

Corrosive, irritant, causes burn, has an irritating vapour and stains.

      Furthermore, it needs to have garlic roots and hot/cold water, and lab equipment for doing the experiment.

  1.  The working methods of this lab work are:
  2.  The first step is putting a test tube with 2 cm³ 1 M hydrochloric acid into 60ºC water bath.
  3.  Some root tips of growing garlic root was cut off for about 1 cm. Root tips should be white and rounded up in end.
  4.  The root tips were put in a watch glass that comprises about 2 cm³ of acetic alcohol for at least 10 minutes.
  5.  The root tips were replaced to second watch glass with about 5 cm³ ice-cold water. It was left for 4-5 minutes, then root tips were dried on filter paper.
  6.  The root tips were put into pre-heated hydrochloric acid for properly 5 minutes.
  7.  The step 3 was repeated.
  8.  2-3 mm of root tip was cut in its rounded tip.
  9.  The root tip was gently broke up by a mounted needle, then a one drop of acetic orcein stain was added, and left for 2 minutes.
  10.  The ready root tip was prepared for microscopic view, and was viewed under x400 magnification.

In this experiment, the variables are time and measurement in length of root tips and volume of liquids. This lab needs some work with time to have an appropriate result, however, the highest variable is time as it may change variably. Measurements such as length and volume are also variable, because there are can be uncertainty in equipment. These variable are controlled by doing the experiment many times with several many root tips to have an exact results.

Health and Safety: In the table above, all the potential safety hazards are shown. So, the precautions for them are:  be careful using orcein ethanol stain, acetic alcohol and wear eye protections and gloves as well. Avoid any contact with eye and skin. Follow the lab room rules, and be maximum accurate during the lab experiment.

  1.  Results

  1.   Identifying cells in the following stages of mitosis.

―Interphase.

 This stage was observed by the view of cells to being ready for cell division and chromatin was condensed.

―Prophase.

 Nucleoli got gradually disappear and chromosomes lined up.

―Metaphase.

 This stage was noticed by forming the spindle.

―Anaphase.

 The chromatids of each chromosome have separated slowly and the little daughter cells were noticed and moved away from each other.

―Telophase.

  Two daughter cell were formed.

  1.  Number and Percentage of cells in each stage of mitosis.

Phase

Number of cells

Percentage of cells

  1.  Interphase

67

65.69 %

  1.  Prophase

11

10.78%

  1.  Metaphase

8

7.84%

  1.  Anaphase

5

4.90%

  1.  Telophase

9

8.82%

Total number of cells – 102

  1.  Mitotic index

Mitotic Index =

Mitotic Index:  

These results were taken by the last measurement, because the first two observations were weak and inappropriate to investigate. So, there were 3 measurements repeated and the last one only was the most exact one.

  1.  Discussion

  1.  I could ensure that my results are reliable, because the results were taken precisely concrete. They are valid, as they are really rely on the aim and topic of experiment.
  2.  This experiment is full of using dangerous liquids, as ethanoic stain, acetic alcohol and hydrochloric acid. In this case, wear eye protection and avoid any contact to skin and eye. They are highly flammable, so wear special lab clothes and be careful while the experiment.
  3.  During the experiment the middle lamella was broken down, and the reason why this did occur is – the takin away the things that hold cell together will help to get better result. Middle lamella holds cells together, so by destroying that, we can observe the better result.
  4.  Cells are growing rapidly, so we can see few dividing cells in one moment. As initially it grows faster, then slows down. So, I suggest, getting older is the major reason of finding few dividing cells in root tips.

  1.  Conclusion

In this lab work, we have learned how to observe mitosis in root tips. We studied to prepare the plant tissue and observe in under microscope. We developed our experimental skills while working. We get know more about health and safety precautions. Also, we investigated how to record the results, counting number cells, and percentage and mitosis field. Moreover, we learned how to have a precise result. Even it was difficult to see the mitosis under microscope and find the most reliable result, I can say that we did justify by our results and we did achieve our aim and objectives.

  1.  References

  1.  BBC. 2014 “Producing new cells.” n.d.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/growth_development/newcellsrev1.shtml

  1.  Dawson, Marcella. 2002. “Stages of Mitosis.” Last modified March 2002.

http://teachertech.rice.edu/Participants/dawsonm/cells/Stages_of_Mitosis.htm 

  1.  Gregory, Ph.D., Michael. 2012. “Mitosis and Meiosis.” n.d.

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20laboratory/mitosis/mitosis.htm 

  1.  Kent, Michael. 2000. Advanced Biology. Oxford: Oxford University Press.

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20laboratory/mitosis/mitosis.htm 


 

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