MITOSIS LABORATORY – MICROVIEWER 55

  1. The following eight microviewer slides show the photographs taken from a single ______. The cells were taken from the rapidly dividing region called the “meristem”.
  1. Go to Slide #1, find cell “A” that is in the resting stage called ______.

a)Name 2 important events that occur during Interphase.

______

______

b)Describe what the nucleus looks like.

c)Label the following organelles: nuclear membrane, nucleolus, cell wall, cytoplasm

  1. Go to Slide #2, locate the cell in the middle that is undergoing the second stage of the cell cycle called ______.

a)Are chromosomes now visible during prophase?

b)What has happened to the genetic material to make them clearly visible inside the nucleus?

c)Describe the changes that have occurred to inside the nucleus (i.e. nucleolus & nuclear membrane).

d)What features allow you to identify this cell as a plant cell and not an animal cell?

  1. Go to Slide #3, locate cell “C” that has reached the middle stage of mitosis called ______.

a)Describe where the chromosomes are now located in relation to the cell.

b)Can evidence of chromosome duplication be observed now? Explain the appearance of the chromosomes.

c)What are the fibres called that become visible during this phase?

  1. Go to Slide #6, locate cell “F” that is the late stages of ______.

a)Describe what is occurring to each chromosome during anaphase.

b)What term is given to the genetic material during this phase? ______
What letter of the alphabet does it resemble? ____

c)Toward what area of the cell are chromosomes being directed? ______

d)What structure is responsible for the movement of chromosomes during this phase?

  1. Go to Slide #7, locate cell “G” that is in the last stage of mitosis called ______.

a)There are _____ sets of chromosomes that are tightly forming a dense mass at each ______. Each of these mass will eventually become the ______of the cell.

b)What cell parts begin to reappear during this phase?

c)What cell parts begin to disappear during this phase?

  1. Then look at Slide #8, locate cells “H” which shows late ______and the two genetically ______daughter cells.

a)How many cells have now formed from the original cell?

b)The daughter cells are genetically (identical/different) from each other. (Circle one)

c)Once the cell finishes telophase, it will then enter this next phase of the cell cycle ______.

d)In order to form 2 fully independent cells, what structure/organelle must be formed between the two daughter cells? ______

Part B – Determining the Rate of Cell Division (Onion Root Tip)

a)For each of the following cells from (1 to 12), identify the stage of the cell cycle.

1______7 ______

2______8 ______

3______9 ______

4______10 ______

5______11 ______

6______12 ______

b)Majority of the cells are found in this stage of the cell cycle: ______

c)Is this a realistic portrayal of an onion root tip? Explain.

DETERMINING THE RATE OF CELL DIVISION

PURPOSE: to identify different stages within the cell cycle and to observe changes in the genetic material as it undergoes mitosis.

MATERIALS: microscope, prepared slides of onion root tip (Allium) longitudinal section, microviewer, microviewer slide (Plant Mitosis – Set 55)

PROCEDURE – Microscope & Slide

  1. Locate with a microscope the region of rapidly dividing cells on the prepared slide of the onion root tip, as shown in Figure 15-1.
  1. After locating the cells under low power, switch to medium & then high power. *Note: make sure that the specimen is well-focused before changing magnification.
  1. Count 20 cells that are next to one another in the onion root tip. Determine which of those cells are dividing (i.e. mitosis).
  1. Complete the chart below by recording the number of cells you found in each phase of the cell cycle. Use the diagrams below to help you identify each stage.

Phase / Number of Cells / *Percentage of total in phase / **Pie Graph
(degree)
Interphase
Prophase
Metaphase
Anaphase
Telophase
TOTAL / 20 / 100% / 360o

*to calculate percentage total, take the number of cells divide by 20 and multiply by 100.

**to calculate degree for pie graph, change the percent into a decimal place and multiply by 360.

INTERPHASEPROPHASE

METAPHASEANAPHASE

TELOPHASE

  1. Using the pie graph below, indicate how much of each phase takes up the entire cell cycle. *Note: you will need a protractor to help you graph your information. Make sure to include a legend and colour code each phase of the cell cycle.

Analysis Questions:

a)What stage/phase were the majority of the cells in?

b)Is your data accurate with the actual cell cycle? Explain.