Cell Cycle and Mitosis Tutorial

Transcription

1 Cell Cycle and Mitosis Tutorial Get Started Interphase Prophase Metaphase Anaphase Telophase Take the Quiz

2 What is the Cell Cycle? All cells go through a series of events in their life. Cells grow, divide, perform their necessary function, divide some more, and eventually die. As they grow and divide, a series of changes take place in order for the cell to properly divide. These stages are known as the cell cycle. Resting Cell Two Daughter Cells As a cell progresses through the Cell Cycle it will enter the mitosis stage in the life of the cell. This is where the nucleus and cell divide to make two daughter cells.

3 Daughter Cells Resting Cell Daughter cell is the name given to the two cells that exist when the process is finished. Because the DNA in each cell should be an exact copy, the two cells should be genetically identical. The steps that took place to create these two daughter cells is what this tutorial will address. Two Daughter Cells The Cell Cycle can be broken down into 5 major steps: 1. Interphase 2. Prophase 3. Metaphase 4. Anaphase 5. Telophase Proceed to Interphase

4 Interphase The first stage of the Cell Cycle can be subdivided into three separate stages. As you can see in the picture, the majority of the life of the cell will be the Interphase stage. In some cells, the Interphase stage can last decades. Examine the pie graph. What percentage of time is spent in Interphase? 0% 25% 50% 75% 100%

5 Interphase (G1 Stage) G1 Stage The 1 st growth stage of Interphase is called the G1 stage. During this stage, cells are performing normal functions. For example, cells of the intestine are absorbing nutrients. As the G1 stage continues, the cell will grow larger in size. Additional organelles (mitochondria, ribosomes, lysosomes, etc ) are also created in this stage. After all, the cell will eventually split into two cells so new parts will be needed for each new cell.

6 Interphase (S Stage) S Stage The next stage of Interphase is the S stage. This is named S stage because DNA is synthesized during this stage. This means that an extra copy of DNA is created. One copy will be needed for each of the two cells. Here is a molecule of DNA. What will happen to this DNA molecule during the S Stage? It will be duplicated It will be destroyed It will be hidden

7 Interphase (G2 Stage) G2 Stage The 2 nd growth stage of Interphase (3 rd overall stage) is called the G2 stage. Just as the G1 stage, the cell continues to perform its normal functions. For example, cells of the digestive system would continue to release chemicals to help digest food. Again, the cell continues to grow larger during this stage. After all, it is about to split into two cells. Click the proper picture of interphase below to advance to the next stage.

8 Prophase (1 of 2) Now that Interphase is complete, the cell has entered the process of Mitosis. During the next few stages, the nucleus of the cell will divide into two and thus two daughter cells will ultimately be created. Prophase marks the start of mitosis. In the prophase pictures above, you can see the round nucleus is starting to dissolve and break apart. Notice how there are thick chunks inside the nucleus. DNA is normally inside the nucleus and is also normally in a long, linear form (kinda like strands of spaghetti). However, as prophase progresses, the long strands of DNA condense (coil) and tighten into chunky looking structures called chromosomes. In human cells, a total of 46 chromosomes will appear. The advantage of chromosomes is that the DNA is now in an easily moveable package. This will be important in the later stages of mitosis.

9 Prophase (2 of 2) Chromosomes form Key things to notice: -- Chromosomes form -- Nucleus dissolves -- Spindle fibers created Nucleus dissolves Click the proper picture of prophase below to advance to the next stage.

10 chromatid Go Back Metaphase (1 of 2) During Metaphase, the chromosomes (chunks of DNA) that are now fully formed are pulled by protein threads called spindle fibers towards the cell s equator (center). Spindle fibers act like a rope and lasso. Once the chromosomes are lassoed, the spindle fibers pull the chromosomes to the middle of the cell. The spindle fibers attach to locations on the chromosomes called the centromere. Notice in the two pictures above how the thick chunks called chromosomes appear near the middle of each cell. chromosome

11 Metaphase (2 of 2) chromosome Notice the chromosomes have been pulled to the cell equator. Just like the real picture to the left. chromatid Here is a cartoon picture of a cell with three X shaped chromosomes. Click the play button to see what the spindle fibers do. Click the proper picture of metaphase below to advance to the next stage.

12 chromatid Go Back Anaphase (1 of 2) When metaphase is finished, remember that the chromosomes have been pulled to the cell s equator. When this is finished, the stage called anaphase follows. Chromosomes (chunks of DNA) are made of two halves. Each half is called a chromatid. In the picture below, you can see that chromosomes resemble the letter X. The yellow half and the blue half are the two chromatids that make up this single chromosome. During metaphase, all the chromosomes are lined up in the middle of the cell. For humans, there are 46 total chromosomes lined up in the middle of the cell. chromosome

13 Anaphase (2 of 2) chromosome During anaphase, the spindle fibers that are still attached to the centromere pulls the chromosomes apart so that one chromatid (yellow) is pulled to one end of the cell and the other chromatid (blue) is pulled to the opposite end of the cell. Because the DNA of each chromatid is identical, each end of the cell will have a compete set of DNA. Cell in metaphase anaphase chromatid Click the proper picture of anaphase below to advance to the next stage. Click the play button to see what the spindle fibers do.

14 Telophase When anaphase is complete, all the chromosomes inside the cell were separated with one chromatid being pulled to each end of the cell. During Telophase, the following events take place: -- the cytoplasm begins to divide in a process called cytokinesis. -- the nucleus has begun to reform around the chromatids of each cell. -- the spindle fibers begin to dissolve and disappear. -- The chromatids that have been pulled to each end of the cell begin to unwind back into the linear (spaghetti) form called chromatin. cytokinesis Click the proper picture of telophase below to advance to the next stage. Chromatids unwind into chromatin Nucleus reforms

15 All Stages Back to Back Interphase Remember that when the process began there was one single cell. But now that Telophase and cytokinesis is complete, the cell has been split into two cells. Examine the pictures below. The pictures take you from the start of interphase (one cell) through the stages of the cell cycle until you finish with two cells. Prophase Metaphase Anaphase Telophase Take me to the quiz. I m ready!

16 Answer each question one at a time. There are 20 total questions. Be sure to fill out your worksheet along the way. 1) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

17 2) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

18 3) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

19 4) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

20 5) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

21 6) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

22 7) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

23 8) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

24 9) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

25 10) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

26 11) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

27 12) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

28 13) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

29 14) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

30 15) Which stage of the cell cycle is this? Interphase Prophase Metaphase Anaphase Telophase

31 16) During which stage of the cell cycle does the nucleus dissolve?

32 17) During which stage of the cell cycle do the chromosomes align along the cell's equator?

33 18) During which stage of the cell cycle does the G1, S, and G2 stages occur?

34 19) During which stage of the cell cycle does the cell perform its normal functions?

35 20) During which stage of the cell cycle are the chromatids pulled to each half of the cell?

36 The End I hope this tutorial was helpful. Be sure to turn in your worksheet when finished.