Mitosis Lab (Fields) Name: _______________________________Prelab Watch: http://www.bozemanscience.com/ap-bio-lab-3-mitosis-meiosis Do: Worksheet http://static1.squarespace.com/static/50d5cc57e4b0e383f5b1eb34/t/53ea51fee4b0a5efca19e984/1407865342438/AP+Bio+Lab-03+Mitosis+and+Meiosis+Worksheet-WL.pdf

Statistical Analysis of The Cell Cycle & Mitosis Under Experimental Environments

Mitosis is just one part of the cell cycle – in fact, it is usually the shortest part of the cycle. Mitosis (and cytokinesis) alternates with the much longer-lasting Interphase. Interphase counts for about 90% of the cell cycle and can be divided into three subphases: G1 (“first gap”), S (Synthesis), and G2 (“second gap”). During all three of these subphases, the cell is growing by producing proteins and cytoplasmic organelles. It is important to note that this entire cycle is constantly being repeated (assuming the cells have received the signal to repeat this process). In the above picture, the cells are identified as either being in interphase or in prophase, metaphase, anaphase, or telophase (these four represent the four phases of mitosis).

The onion root tip represents a model study of the rate of the cell cycle. After taking measurements of a standard onion root tip, using basic math, we can determine the relative percentage of time spent in any given phase of the cell cycle. These percentages represent the average or expected values for their respective phases. In short, cells that have a larger percentage of cells in one of the four mitotic states are likely to be undergoing the cell cycle at a faster rate. Conversely, cells that have an extravagant percentage of cells in interphase are likely not undergoing the cell cycle with a great rate (perhaps because they are in a nondividing phase).

If onions (and subsequently their roots) are treated with certain chemicals, then perhaps the rate of the cell cycle may change depending on the chemical added. In the case of stimulatory chemicals or enhancing chemicals such as cyclin, the rate of the cell cycle should be expected to increase. If an inhibitory chemical is added, the rate of the cell cycle should be expected to decrease. Using the above picture and the pictures below, you will study the statistics (utilizing basic percentage skills and chi-square analysis) to determine the effects on two different chemicals on onion root tip growth.

Interphase Prophase AnaphaseMetaphase Telophase

Mitosis Lab (Fields) Name: _______________________________

The following picture represents the control – an onion root tip that was not given a stimulatory chemical (such as cyclin) or an inhibitory chemical. In other words, this represents a root tip that is under normal or standard conditions. If a cell cannot be distinguished because of poor image quality, simply do not factor it into the statistical analysis.

Phase of the Cell Cycle

Number of Cells

Percentage of Cells

Number of Minutes Per Day Spent in that Phase

Interphase

Prophase

Metaphase

Anaphase

Telophase

Mitosis Lab (Fields) Name: _______________________________

The following picture represents an experimental test – an onion root tip that was given a stimulatory chemical (such as cyclin). In other words, this represents a root tip that may possibly not be undergoing standard rates of the cell cycle. To determine if the chemical is in fact able to stimulate the cell cycle, collect date and perform a chi square using the expected values from the control test. HINT: I would suggest studying the percentages during this analysis. If a cell cannot be distinguished because of poor image quality, simply do not factor it into the statistical analysis.

Phase of the Cell Cycle

Number of Cells

Percentage of Cells

Number of Minutes Per Day Spent in that Phase

Interphase

Prophase

Metaphase

Anaphase

Telophase

Mitosis Lab (Fields) Name: _______________________________

What are the implications of the chi-square analysis? What statements can be made? What conclusions can be drawn about the chemical in question?

Chi Square Analysis

Mitosis Lab (Fields) Name: _______________________________

The following picture represents an experimental test – an onion root tip that was given an inhibitory chemical (having the opposite effect of cyclin). In other words, this represents a root tip that may possibly not be undergoing standard rates of the cell cycle. To determine if the chemical is in fact able to inhibit the cell cycle, collect date and perform a chi square using the expected values from the control test. HINT: I would suggest studying the percentages during this analysis. If a cell cannot be distinguished because of poor image quality, simply do not factor it into the statistical analysis.

Phase of the Cell Cycle

Number of Cells

Percentage of Cells

Number of Minutes Per Day Spent in that Phase

Interphase

Prophase

Metaphase

Anaphase

Telophase

Mitosis Lab (Fields) Name: _______________________________

What are the implications of the chi-square analysis? What statements can be made? What conclusions can be drawn about the chemical in question?

Chi Square Analysis