How do Living Things Grow and Repair Themselves - Mitosis

BioQuest:Cell Cycle and Mitosis Name Mitosis Date__ Per_ How do living things gr<'w and repair tl1emselves? Why? J wear out. New cells must Ье formed for tlie living thing to sieve. Model 1 Nucleolus Prophase Replicate Cell Cycle Metaphase Anaphase G 1 + 5 + G 2 = lnterphase М = nL1clear & cytoplasmic division 1. List tlie pliases in tlie 1'hitosis process bу looking at Model 1. Tl1ere .age four pl1_ases. 2. Wl1ere is 1nitosis in tlie cell cycle? Before • Z 3. What three phases of the cell cycle are consid,ered "inte1phase"? 4. а) Ho,v many cells are present at the end of G2? J Ь) How many cells are present at the end of М? 2... 5. What shape do the replicated chromosomes look like in Qro2hase of the original cell? х. 6. How many chromatids are in eacl1 replicated chromosome? 7. How many replicated chromosomes are there in the original cell during p.ropl1ase? (Нint: When counting chromosomes, count "1" for а pai1· of sister chromatids) 8. How many single chromosomes are there in each of the new cells in telophase? 9. Уour answers to 7 and 8 should Ье d1e same. Why is this important? Chromosomes are made ofDNA wound around proteins. They contain all the genetic infor1nation of d1e living organism. Before d1e cell divides d1e chro1noso1nes in the original parent cell must fu:st Ье douЫed (replicated). Tlus happens so d1at wl1en the cell divides into t"\vo ne,v cells, bod1 ,vill Ье identical to the parent cell. 1О. As а group, ,vrite а gra1n1natically correct sentence d1at explains ,vliat а chro1noso1ne is and ,vЬу it is iinportant. 11. Tl1e clirom&omes that are sl1aped like ''X's" (1nade of t"\vo sister chro1natids) l1ave douЬle d1e amount ofDNA tЬan d1e cliro1noso1nes tЬat are sl1aped Ы:е "I's". During ,vhat pl1ase of tЬе cell cycle do you clщik tЬе chro1nosomes are replicated (copied)? .S 12. Describe the difference in appearance between tЬе chro1noso1nes during propl1ase in tЬе original cell and tЬе chromosomes in tЬе t"\vo ne,v cells in telophase. 13. Tl1e S phase stands for synthesis, wliich 1neans to make s01netЬing. Scientists know that during tЬе S pl1aseDNA is being 1nade in tЬе nucleus of tЬе cell. Why do you tЬink tЬе cell needs to 1nake 1noreDNA at this tiine in the cell cycle? 16. During wE.at phase to you see that the spindle fibers have clisappeared? 17. Look at metaphase and anaphase. What do you think фе function of the �pindle fibers is dw:ing mitosis?10 18. Describe happens to the nuclear membrane after prophase. 19. Why do you think it is necess�1-y to clisintegrate the nuclear membrane during mitosis? 20. Ву the end of wl1at phase of mitosis Ьаs the nuclear 1nembrane refor1ned? 21. What stt-ucture reappears in the nucleus after _cytokinesis? 22. What is actually' clividing dw:ing cytokinesis? 23. Cellular clivision has t\vo parts: mitosis is tl1e clivision of the nucleus and cytokinesis is the clivision of the cell into two new cells. Explain why 1nitosis has to come before cytokinesis in 24. Dw:ing cytokinesis the chro1noso1nes uшvind and beco1ne а pile of ve1y long, tl1in, threadlike DNA and the cell goes back to looking "nor1nal" until mitosis begins. Brainstorm "vith your group ideas "\vhy the DNA must coil up into cl1ro1noso1ne structures be.fiп-e it clivides. 25. Make а tаЫе belo"\v wl1ere you list each of tl1e phaes of nuclear and cell clivision in tl1e left l1and column and· а word description of "vhat is happening during that pl1ase in the right l1and column. Phase of Cellular Division 26. In some cells, mitosis occurs WITHOUT cytokinesis. What· would the resulting cell look like? 27. Explain the importance of mitosis of cells in а skinned knee and during the growth of а plant. 28. Wid1 your group consider the effect on а cell if the sister chromatids did not line up correcdy during 1netapl1ase. For exa1nple if some lined up side Ьу, sic;:le instead of single file along tl1e middle, how might this affect the resulting cells? Extension _Questions 29. Colchicine is а poison d1at acts to inhiЬit the development of spindle fi.bers. Describe tl1e effects on mitosis in а cell that has been treated wid1 colchicine.