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Student Exploration: Cell Division

Vocabulary: cell division, centriole, centromere, chromatid, chromatin, chromosome, cytokinesis, DNA, interphase, mitosis

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

1. Cells reproduce by splitting in half, a process called cell division. What do cells need to do between divisions to make sure that they don’t just get smaller and smaller?

The cell needs to go through a phase after cell division.

2. The genetic information of a cell is carried in its DNA (short for deoxyribonucleic acid). What do cells need to do between divisions to make sure that a full set of DNA gets passed on to each daughter cell? Cells need to synthesis DNA molecules to make sure that a full set of DNA gets passed on to each daughter cell.

Gizmo Warm-up
On the SIMULATION pane of the Cell Division Gizmo™, check that the Cycle Length is set to 12 hours. Click Play ([pic]), observe until the maximum number of cells is shown, and then click Pause ([pic]).

1. Look at the cells. Do they all look the same? All the cells look the same but some of them are in different stages of cell division.

2. Cells that are in the process of dividing are said to be in mitosis or cytokinesis. Cells that are not dividing are in interphase.

Check the Magnify box and move the cursor over the cells.

A. Of the 100 cells shown, how many are in the process of dividing? 15

B. Select the BAR CHART tab, and turn on Show numerical values. How many cells are in the interphase stage of their life cycle? 85 C. Based on these two observations, would you say that a cell spends most of its life cycle in interphase or in mitosis/cytokinesis? Interphase

|Activity A: |Get the Gizmo ready: |[pic] | | |Click Reset ([pic]). | | |Phases of the cell cycle |Select the DESCRIPTION tab. | | | |Click on the right arrow once so that Interphase is shown. | |

Question: What are the stages of the cell cycle?

1. Observe: Click Play and hold the cursor over the cell. Observe the cell as it divides several times. (This happens quickly!) What do you notice happening during this process?

The cell replicates itself and separates into two daughter cells.

2. Summarize: On the DESCRIPTION pane, read about each phase in the cell cycle. In the spaces below, summarize what occurs in your own words.

|Phase |Summary | |Interphase |Longest phase of the cell cycle in which the cell grows. The phase is divided | | |into 3 stages; G1 (RNA and proteins are synthesized), S (DNA is synthesized), | | |and G2. | |Prophase |The nucleolus and nuclear membrane disappear. Spindle fibers form between the | | |centrioles. | |Metaphase |Spindle fibers attach to centromeres of chromosomes and chromosomes line up | | |along the equator of the cell. | |Anaphase |Sister chromatids are pulled to opposite poles of the cell. | |Telophase |Nuclear membrane forms and nucleolus reappears and chromatids unwind into | | |chromatin. | |Cytokinesis |The...
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