Biology Lab - frequency of cell division in animal and plant cell

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Frequency of Cell Division in Animal and Plant Cell

2008-10-15

DESIGN:

Question:

How is the process of mitosis different between onion root tip cells and whitefish blastula cells?

Hypothesis:

If the percentage of prophase is the highest percentage of cells in division among mitotic phase for both onion root tip cells and whitefish blastula cells, then it means that interphase is the most occurring phase in mitosis because all stages must go though interphase before proceeding to other stages of mitosis. The differences between onion root tip cells and whitefish blastula cells in process of mitosis might happen in telophase. Since onion root tip cell is a plant cell, in telophase, it will produce cell plate in order to divide. However, in telophase, since whitefish blastula cell is an animal cell, it will produce cleavage furrow to divide into two separate cells.

Variables:

Controlled variable is a microscope because it doesn’t make changes. Independent variables are the slides because it doesn’t change but other variables are dependent on the slides. Dependent variables are the phases of mitosis in cells because they differ depending on the slide we observe through.

Materials:

  • Compound microscope
  • Prepared slides of onion root tip
  • Prepared slides of whitefish blastula

Procedure:

Onion (Allium) Root Tip:

Onion (Allium) root tip slide was prepared and was placed it on the stage on the compound microscope. It was first viewed under the low-power magnification and the slide was adjusted so that the slide was focused at the centre of the field of view. The coarse-adjustment was used to move the stage closer to the objective lenses for the clear view of the slide. The fine-adjustment was used to have a clear look at the slide. To have more focused and detailed view, nosepieces of the microscope were rotated to medium-power and then to high-power. Each stages of mitosis cycle were drawn on the diagram. The actual length, width and the magnification of the cell and the frequency of the mitosis were recorded and calculated on the back of the diagram. At the end, the calculated magnification of the cell was recorded on the bottom right of the diagram. The length and width of the cell and how many times it would fit across the width and the length of the field of view were estimated and recorded on the paper. To remove the slide, the nosepieces were rotated back to low-power and the coarse adjustment was used to put the stage further away from the objective lenses.

Whitefish Blastula (Feuilgn Stain):

Whitefish Blastula (Feuilgn Stain) slide was prepared and was placed it on the stage on the compound microscope. It was first viewed under the low-power magnification and the slide was adjusted so that the slide was focused at the centre of the field of view. The coarse-adjustment was used to move the stage closer to the objective lenses for the clear view of the slide. The fine-adjustment was used to have a clear look at the slide. To have more focused and detailed view, nosepieces of the microscope were rotated to medium-power and then to high-power. Each stages of mitosis cycle were drawn on the diagram. The actual length, width and the magnification of the cell and the frequency of the mitosis were recorded and calculated on the back of the diagram. At the end, the calculated magnification of the cell was recorded on the bottom right of the diagram. The length and width of the cell and how many times it would fit across the width and the length of the field of view were estimated and recorded on the paper. To remove the slide, the nosepieces were rotated back to low-power and the coarse adjustment was used to put the stage further away from the objective lenses.

DATA COLLECTION AND PROCESSING:

Raw Data Table:


Table 1. Data collected while observing the prepared slides of onion root tip in class. Number of cells in phase was calculated by counting 20 adjacent onion root tip cells and the cell which are in interphase or actively dividing stage was determined.

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Table 2. Data collected while observing the prepared slides of whitefish blastula in class. Number of cells in phase was calculated by counting 20 adjacent whitefish blastula cells and the cell which are in interphase or actively dividing stage was determined.


Table 3.        Data collected while observing the prepared slide of onion root tip in class. Class was divided into pairs and they each drew the diagrams of the process of mitosis of each stage. All students in the class recorded the data which was needed to calculate the field of view, drawing of ...

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