Cell Cycle & Division Tutorials

1. Cell Cycle & Division Tutorials vocabulary tutorial SA:V ratio activity review

2. Introduction • What do you think these cells are doing? • List 3 ways the nuclei of these cells differ from each other Answer the questions, then click forward

3. Introduction • What do you think these cells are doing? - they are dividing • List 3 ways the nuclei of these cells differ from each other - the placement of the chromosomes, - the presence of the nuclei and/or nuclei membranes - presence of an intermediate cell plate Next….

4. What must cells do within interphase in order to divide? Answer this question, then click forward

5. What must cells do within interphase in order to divide? • DNA must copy & form into sister chromatids • Cells must have enough organelles (like mitochondria) for 2 cells. Next….

6. What must cells do in prophase in order to divide? Answer this question, then click forward

7. What must cells do in prophase in order to divide? • Nuclear membrane must break down • Chromatin must condense into chromosomes • Centrioles must form (in animal cells) Next….

8. The Stages of Cell Division What happens in each stage? Click to find out.

9. The Stages of Cell Division Prophase: condensing of chromosomes, disappearance of the nuclear membrane Metaphase: lining up of chromsomes (2 sister chromatids) along the cell’s equator Anaphase: the 2 sister chromatids are pulled to either pole of the cell by shortening spindle fibers. Telophase: nuclear membrane reforms, cleavage furrow forms to divide the cell into two parts. Next….

10. Early Prophase What are the arrows pointing to? What is happening? How many strands of chromatin are there? Are the strands of chromatin paired? Answer the questions, then press the forward button.

11. Early Prophase nucleolus nuclear membrane chromatin What are the arrows pointing to? What is happening? Chromsomes, The cell grows 4 How many strands of chromatin are there? Are the strands of chromatin paired? There are 2 pairs but they are not paired up together.

12. Late Prophase What two things have happened? Answer this question, then click the forward button.

13. Late Prophase What two things have happened? • Nuclear membrane and nucleolus have broken down • Chromosomes have coiled & become double chromosomes Next…

14. Metaphase What 2 things have happened? Answer this question, then press the forward button.

15. Metaphase • Double chromosomes have lined up on the equator. • Spindle Fibers have attached to the centromeres. What 2 things have happened? Next…

16. Anaphase What has happened? Answer this question, then press the forward button.

17. Anaphase • Centromeres have split and the 2 sister chromatids are being pulled to opposite poles (once they separate, they are called chromosomes. What has happened? Next…

18. Telophase What structure is the arrow pointing to? What three things have happened? Answer the questions, then press the forward button.

19. Telophase Cell plate What three things have happened? • Nuclear membrane and nucleolus reappear • Chromosomes uncoil and become chromatin • Cytokinesis occurs after telophase (cytoplasm divides) Next…

20. Analysis • How did the number of cells change? • How did the number of chromosomes in each cell change? • Were the chromosomes in each cell always paired? • What would happen if one of the double chromosomes did not line up on the equator at metaphase? Answer these questions, then press the forward button.

21. Analysis • How did the number of cells change? • There was one cell to begin with, and at the end there were two cells. • How did the number of chromosomes in each cell change? • There were four chromosomes in the beginning cell, and four chromosomes in each of the new cells.. The number stayed the same.

22. Were the chromosomes in each cell always paired? • There were always 2 of each pair and the new daughter cells had 2 of each pair but they chromosome pairs weren’t attached together. • What would happen if one of the double chromosomes did not line up on the equator at metaphase? • The chromatids would not get separated and the new cells would have the wrong number of chromosomes. (one too many and one too few) Back to the Main Menu

23. SA:V Activity: Why do cells divide? • Problem: Many cells grow until they reach a certain size and then divide. Why don’t cells grow indefinitely until they become the size of basketballs? What are some problems that arise when a cell grows larger? Why does a cell divide into two smaller cells when it reaches a certain size? What are some factors that might limit cell growth?

24. Hypothesis: It is possible that it is more difficult for cells to get materials (food, water, oxygen) to the inside as they get larger because volume increases more than surface area increases. Therefore, “If a cell is smaller, it is able to get materials inside easier than larger cells.”

25. Experiment: three phenolphthalein agar cubes will represent three different sizes of cells. The cubes will be placed in a NaOH solution that will diffuse into them for 7 minutes. As the diffuse, the high pH will change the white blocks to pink. At the end of 7 minutes, the cubes will be cut open and the distance the solution diffused into each cube will be measured in millimeters. 3 cm. cube 2 cm. cube 1 cm cube

26. Press the button below to put the cubes in the beaker. Start experiment

27. Waiting 7 minutes... • What is the variable in this experiment? • What are the controlled variables (constants)? • What is the data you are collecting (dependent variable)? • How many trials should be done? Answer these questions, then press the forward button.

28. Waiting 10 minutes... • What is the variable in this experiment? • size of the cubes (cells) • What are the controlled variables? • same solution, temperature, time in solution • What is the data/dependent variable? • distance solution diffused into cubes (mm) • How many trials should be done? • each set of 3 cubes is one trial; you should do at least 3 sets (but we will do only one)

29. Results: Each cube is cut open and the distance that the solution diffused into the cube is measured.

30. Data: Distances NaOH diffused into phenolpthalein agar cubes as indicated by pink area (pretend the inch is really cm!!) What is missing in the table?

31. (This graph was made from the raw data on the previous slide) What other way could you process the data in order to make your conclusion? Which conclusion on the next slide is correct based on the results shown in the graph below?

32. A B C • Food and water diffuse into any size cell at the same rate. • Smaller cells can get food and water to the center the fastest. • When cells divide, they get smaller so the materials & wastes can travel throughout the cell quicker. A only B only C only A, B, & C A and B A and C

33. Sorry, try again! Click here to look at the graph again Click here to go back to the answers

34. Correct! Now let’s see if you can answer this question. Use the concepts from this activity to explain your choice. • Which person would likely get overheated more quickly, an infant or a teenager? • For an extra challenge, calculate the surface area and volume of 1” and 2” cubes. Show how the volume increases faster than the surface area as a cube gets larger. (volume increases about 10x faster. Return to main menu

35. Chromosome - DNA and protein in a coiled state Vocabulary

36. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Vocabulary

37. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Sister chromatids - a chromosome attached to its copy Vocabulary

38. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Sister chromatids - a chromosome attached to its copy Chromatid - one half of a double chromosome Vocabulary

39. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Double chromosome - a chromosome attached to its copy Chromatid - one half of a double chromosome Centromere - the “skinny” area of a chromosome where two chromatids are attached, this is also where the spindle fibers attach Vocabulary

40. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Double chromosome - a chromosome attached to its copy Chromatid - one half of a double chromosome Centromere - the “skinny” area of a chromosome where two chromatids are attached, this is also where the spindle fibers attach Vocabulary Mitosis - division of the nucleus, interphase is not part of mitosis

41. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Double chromosome - a chromosome attached to its copy Chromatid - one half of a double chromosome Centromere - the “skinny” area of a chromosome where two chromatids are attached, this is also where the spindle fibers attach Vocabulary Mitosis - division of the nucleus, interphase is not part of mitosis Cytokinesis - the process in which the cytoplasm divides

42. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Double chromosome - a chromosome attached to its copy Chromatid - one half of a double chromosome Centromere - the “skinny” area of a chromosome where two chromatids are attached, this is also where the spindle fibers attach Cytokinesis - the process in which the cytoplasm divides Cell plate - cell wall (plant cells) Vocabulary Mitosis - division of the nucleus, interphase is not part of mitosis

43. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Double chromosome - a chromosome attached to its copy Chromatid - one half of a double chromosome Centromere - the “skinny” area of a chromosome where two chromatids are attached, this is also where the spindle fibers attach Cytokinesis - the process in which the cytoplasm divides Cell plate - cell wall (plant cells) Vocabulary Mitosis - division of the nucleus, interphase is not part of mitosis Cleavage furrow - pinching of membrane (animal cells)

44. Chromosome - DNA and protein in a coiled state Chromatin - DNA and protein in an uncoiled state Double chromosome - a chromosome attached to its copy Chromatid - one half of a double chromosome Centromere - the “skinny” area of a chromosome where two chromatids are attached, this is also where the spindle fibers attach Kinetachore – protein ‘handle’ on a doubled chromosome that allows spindle fibers to attach during mitosis Cytokinesis - the process in which the cytoplasm divides Cell plate - cell wall (plant cells) Vocabulary Mitosis - division of the nucleus, interphase is not part of mitosis Cleavage furrow - pinching of membrane (animal cells)

46. To main menu

47. Let’s Review! 1. The “chromosomes” to the right are different because a. they are made of different substances b. in one, the DNA is coiled up and in the other it is not coiled c. one is found in animal cells and the other is found in plant cells d. they are found in different parts of the cell 2. In the diagram to the right, the DNA in the chromosome has a. divided b. done nothing c. replicated d. none of these answers

48. A B C D E 3. What is wrong with this cell? a.. The double chromosomes are being pulled apart b. The chromosomes are being pulled to the poles c. One of the double chromosomes is not being pulled apart d. There is nothing wrong with this cell 4. List the name of the stage of mitosis each of the following cells are showing. Then list why the cell is is that stage (what events are happening). Finally list what order they should go in. 5. Why do cells divide when they reach a certain size?