Lab Report Of Garlic Hair Root Mitosis Writing Assignment (Lab Report Sample)

BIOLOGY
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Abstract
Cell division is a key process that ensures continuity of cells lineage. Among the types of this process is mitosis. This practical is meant to demonstrate stages of the process and calculate the population of the cells at each stage. Five phases are involved in mitosis and in each phase, activities are done to a dividing cell. Different stains can be used to stain structures of the cell but in this practical, toluidine blue and aceto-aorcein are used to stain nucleus for easy identification in microscope. In this practical, cells are observed at each phase under a light microscope and mitotic index is then calculated and then the index is compared to other phases. The process of mitosis is utilized majorly in the human body for maintaining growth and replacing dead cells.
Objectives
The aim of the practice is to prepare, observe and identify the cells at different phases of mitosis in a meristematic tissue from root tips then photograph them and this information used to calculate the mitotic index. This practical also is meant to sharpen skills of microscope handling in students: viewing and illumination to get accurate results.
Introduction
Mitosis is a process of cell division where double similar daughter cells are yielded. There are two classifications of cell division: meiosis and mitosis. Meiosis is the process that takes place in sex cells while mitosis occurs in somatic cells. Mitosis ensures cell growth and also the replacement of worn out or dead tissue. Some organism reproduced by means of cell division (mitosis). During this process, chromosomes are replicated and two similar nuclei are produced. This process occurs in five steps: interphase, prophase, metaphase, anaphase and telophase. During the interphase, the DNA is duplicated in preparation of consequent mitosis (Kanopy (Firm), 2016) Here, chromosomes are not seen in the nucleus clearly. In the prophase stage, the nuclear membrane is dissolved and the chromatin starts to condense. They are seen under a microscope. Microtubules structures become linked to kinetochores and they start to move. Kinetochores are structures that lead to the formation of chromatids when a cell is dividing and makes it possible for a spindle fibre to attach to a chromosome. The cell then enters the metaphase stage where chromosomes become aligned by spindle fibres in the centre of the nucleus (metaphase plate) (Taiz, Zeiger, Møller, & Murphy, 2015). This alignment aids to ensure that during the next phase when chromosomes will be partitioned, a single copy of new nucleus will be placed on each chromosome. In the anaphase step, the cell the chromosomes which are in pairs begin to move to opposite ends. During the last stage of telophase, the daughter cells are the surrounded by new membranes and the chromosomes are seen to disperse (Films for the Humanities & Sciences (Firm), Films Media Group, & TVOntario, 2009).
Materials
* Water bath (600C)
* Scalpels and scissors
* Microscope
* 1M Hydrochloric acid
* 100ml beaker
* Paper towels
* Watch glass
* Coverslip and microscope slip
* Mounted needle
* Toluidine blue and aceto-orcein in dropper bottles
* Garlic with sprouting roots
* Ethanoic alcohol in dropper bottles
Procedure
* 2cm of the root tip was cut off and placed in 1ml of ethanoic acid on a watch glass while 20ml 1M hydrochloric acid was heated using hot water bath
* They were then washed for 4 minutes in cold water, dried and then transferred to hot hydrochloric acid and left for 5 minutes
* They were then rewashed for 5 minutes in cold water and dried then placed on a clean microscope slide and in each, a piece of 2 mm was taken from root tip and the other parts kept
* A drop of toluidine blue and another drop of aceto-orcein were each placed on each root tip and mounted needle was used to break up the tips
* After the covering with a coverslip, it was then squashed by a dropped mounted needle to hit the center of the coverslip.
* The root tissues were then seen under a microscope at an enlargement of x400 and chromosomes and the meristematic zone were located.
* Photographs of cells seen under a field of view were taken at different stages of mitosis and the mitotic index calculated then compared to different days.
Results
The photographs below show the microscopic view of root tip cells division on day 2
Mitotic index was calculated as follows:
= Amount of dividing cells in the field of view divided by total count of cells in the field of view
= 8/22 = 0.36
The photographs below show the microscopic view of root tip cells on day 5
Mitotic index = Count of cells dividing cells in the field of view divided by total count of cells
= 5/33 = 0.15
Discussion
During the practical, garlic root was used because they are readily available to acquire in the lab. Also because garlic has a meristem in the root apex which consists of a large number of rapidly dividing cells that can be viewed easily in the microscope (Beeckman, 2010). This meristem has cells that are in the different stages of mitosis hence each distinct phase can be observed clearly. Hydrochloric acid was added to break the bonds that exist between the cells without destroying the cell walls making the nucleus easily reached. They also make the root softer. This acid also stops the process of mitosis hence keeping cells remain constant at their respective stages of mitosis (Nielsen, 2009). To make sure that the results are more accurate, two root tips are used so as to bring a comparison hence minimizing errors that can be incurred during the practical. Although aceto-orcein was used, toluidine blue is preferred as a method of staining because it is cheaper, reliable and easy to handle. It is meant to stain the nucleus. Ethanoic alcohol was used to prevent chemical and structural changes in the cells while they were being stained and mounted (fixative). Mitotic index is important since it shows the number of cells that are undergoing mitosis at a particular time in a certain population. The bigger it is, the higher the number of cells dividing. This index may be increased in processes like cancer and repair of cells in the human body.
Based on the results above, the largest mitotic index is found to be on the second day where almost all the cells are in the interphase stage. Because interphase has a larger mitotic index, therefore most cells spend a lot of time here waiting for mitosis (Baker, 2010). This preparation is to ensure all that is needed for su...