"cell cycle lab - DOC"
Cell Cycle Lab Question: How long do the stages of the cell cycle take? Background Information: The purpose of this lab is to estimate how long each stage of the cell cycle is. Cells from the tips of onion (allium) roots will be observed. The tip of roots is where the root ___________ and gets longer as it is tapping into water sources. Thus it is an area where cells are reproducing and dividing. The most important part of the cell cycle is making sure the new cell gets a copy of the DNA. Remember the different stages of the cell cycle. _____________ is where the cell does normal cell functions. It ___________, _________________ its DNA and gets ready for cell ____________. The next stage is ___________. Mitosis consists of 4 stages. ___________ is where the DNA coils up to form ______________ and the nuclear membrane breaks down. ________________ is when the chromosomes line up at the center of the cell. ______________ is when the chromosomes get pulled by the spindle fibers to the opposite sides of the cells. _________________ is when a new nucleus forms around each set of chromosomes. After mitosis ____________ happens and the cell membrane halves to form 2 new cells. Procedure: 1. Each group gets a slide that contains 3 onion root tips. 2. Look at the slide on low power first. Select one of the onion root tips. Make sure it is aligned in the middle of the view circle. 3. Eventually focus on medium and then high power. The diaphragm might need to be set on 4 or 5 so the cells appear darker. 4. On high power, examine the cells row by row. Count the cells that are in interphase. Record that number in the data table under first sample. 5. Repeat step 4, this time count the cells that are in prophase, metaphase, anaphase, and telophase. 6. The second person in the lab group repeat steps 2-5 this time enter into the data table under second sample. 7. The third person in the lab group repeats steps 2-5 this time enter into the data table under the third sample. 8. Everyone in the group is responsible for putting the microscope away properly and returning the slide. Data, Calculations, and Graph Data Table st nd rd Stage of Cell Cycle 1 sample 2 sample 3 sample Total number interphase mitosis: prophase mitosis: metaphase mitosis: anaphase mitosis: telophase Total number of cells counted Calculations: Calculate the average (mean) number of cells for each stage. Then calculate the percent for each stage. Label and show your work below. Graph: Make a pie chart out of the percent for each stage. Make sure you label each section of the pie chart. Questions: 1. Which stage of the cell cycle did you observe most often? 2. The cell cycle for onion root tips takes about 720 minutes (12 hours). Use your data and the formula below to find the number of minutes each stage takes. Time for each stage = % for each stage x 720 min. 3. Use the data to compare the amount of time spent in mitosis with the total time for the whole cell cycle (mitosis and interphase).