Mitotic Cell Cycle

Observing Mitotic Cell Cycle in the roots of Onion

INTRODUCTION

The cell cycle refers to sequence of events that takes place in a cell leading to its division and duplication (replication). This process is important to genetics because through the cell cycle genetics information for all sorts are passed from parents to daughter cells. (Griffiths. A et al)

A new cell starts after the division and production of two new cells. Each new cell undergoes metabolism, growth and development. At the end of its cycle the cell divides and produces two new cells which then undergo further cell cycle. (Elseth .G et al)

The cell cycle consist of two major phases the first is interphase (an extended period of cell growth, accumulating nutrients needed for mitosis and synthesizing its D.N.A. The second period is the mitosis phase (M phase) during which the cell splits itself into two distinct cells called daughter cells. (Griffiths. A et al)

Mitosis is broken down into four stages: prophase, metaphase, anaphase and telophase. When living organism needs new cells to repair damage, grow or maintain its condition, cells undergo the cell cycle.

The cell cycle is a significant process by which single celled fertilized egg develops into mature organisms, as well as the process by which hair; skin, blood cells and some internal organs are renewed. (Practical Biology.org)

Aim: the scientific aim of this study is to observe the stages of cell cycles in living tissues, generally and specifically in the meristematic cells of the root of onion or garlic and calculate the mitotic index percentage.

METHOD

1-2 mm of root tip of growing garlic roots were cut off. The root tip was placed in one of the Petri dishes and a few drop of 1 M of hydrochloric acid ...

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...nt the overlapping of cell. Furthermore we used toluidine blue to stain the samples so that the chromosomes can be observed clearly and finally cover slip was used in the experiment to flatten the tip of the onion root for better viewing.

In conclusion, Cell cycle can be divided into interphase and M phase (Mitotic phase). Interphase can be divided into three different phases; they are G1 (first gap) phase, S (synthesis) phase and G2 (second gap) phase. M phase consist of mitosis and cytokinesis. Mitosis, on the other hand consists of four main phases which are prophase, metaphase, anaphase and telophase. The largest stage of cell cycle is interphase, followed by prophase. The shortest would be metaphase, anaphase and telophase. The greater the percentage of cells, the longer the time spent by each cell in that stage. Therefore the hypothesis is accepted.