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CELL DIVISION Cell Division Check off the assignments as you complete them. _____ 1. Read “My Planet Diary” on page 92. Complete ‘Interpret Data’ on the right hand side of the page. _____ 2. Read ‘What Are the Functions of Cell Division’ at the bottom of page 92. _____ 3. Read page 93 in your textbook. Complete ‘Identify’ and ‘Challenge’ for Figure 1 on page 93. _____ 4. Obtain an answer key and check the answers on page 93. Correct anything that is wrong then return the answer key _____ 5. Answer questions 1 and 2 in the “Cell Division” notes that start on page 4 of this booklet. _____ 6. Complete Assess Your Understanding on page 93. _____ 7. Read page 94. Complete ‘List’ for Figure 2 on page 94. _____ 8. Obtain an answer key and check the answers for ‘List’ on page 94. Correct anything that is wrong, then return the answer key. _____ 9. Complete ‘Apply it!’ on the top of page 95. _____ 10. Obtain an answer key and check the answers for ‘Apply it!’ on page 95. Correct anything that is wrong, then return the answer key. _____ 11. Read page 95. Complete ‘Compare and Contrast’ for Figure 3 on page 95. _____ 12. Obtain an answer key and check the answers for ‘Compare and Contrast’ on page 95. Correct anything that is wrong, then return the answer key. _____ 13. Answer questions 3, 4, 5a, 5b, 5c, 5d, and 6 in the “Cell Division” notes. _____ 14. Read pages 96 and 97. Complete ‘Interactive Art’ on pages 96 and 97. _____ 15. Obtain an answer key from your teacher and check the answers for ‘Interactive Art’ on pages 96 and 97. Correct anything that is wrong, then return the answer key. _____ 16. Read page 98. Complete ‘Ask Questions’ on the left hand side of page 98 and ‘Compare and Contrast’ for Figure 5 on the bottom of page 98. _____ 17. Obtain an answer key from your teacher and check the answers for ‘Ask Questions’ and ‘Compare and Contrast’ on page 98. Correct anything that is wrong, then return the answer key. 1 _____ 18. Answer questions 7 and 8 in the “Cell Division” notes. _____ 19. Complete ‘do the math!’ on page 99. _____ 20. Obtain an answer key from your teacher and check the answers for ‘do the math!’ on page 99. Correct anything that is wrong, then return the answer key. _____ 21. Complete Assess Your Understanding on page 99. _____ 22. Obtain an answer key for the notes from your teacher and check the answers. Correct anything that is wrong, then return the answer key. _____ 23. Complete the Mitosis worksheet starting on page 6 of this booklet. 2 Cell Division (Pages 92 – 99) 1. What are the three functions of cell division? (page 93) 2. How do most organisms reproduce? (page 93) 3. What is the cell cycle? (page 94) 4. What happens during the cell cycle? (page 94) 5. Define the following terms: a. interphase: (page 94) b. replication: (page 94) c. chromosomes: (page 94) d. mitosis: (page 95) 6. What is the result of replication? (page 94) 3 7. What is cytokinesis? (page 98) 8. How does cytokinesis differ between plants and animals? (page 98) Mitosis Worksheet cell plate dividing parent centromere division phase chromatids exact phases divide metaphase repairing divides nuclear Directions: Fill in each blank with the word that best completes the reading selection. Cells multiply by dividing. The process known as cell division allows living things to grow bigger. Cell division also helps living things replace old or injured cells. When one cell divides, two new cells take its place. The two new cells are called daughter cells. A human body cell contains 46 (that's two sets) chromosomes. This is called the diploid number of chromosomes. One set of 23 chromosomes came originally from your father while the other set came from your mother. These 46 chromosomes contain all the genetic information to make you, you. As you grow or your body needs ___________________, your cells divide. If you think of chromosomes as a way of packaging DNA, then mitosis is a way of making sure that the chromosomes and the DNA they contain are split equally when a cell divides. Before a eukaryotic cell (that's a cell with a true nucleus) divides, the genetic material in the nucleus of the cell copies itself. When the cell _______________________, the genetic material divides in half so that each daughter cell gets genetic material that is the same as the parent cell's genetic material. The dividing of the ______________________ material is known as mitosis. In the last stage of cell division, the cytoplasm divides as well. That is known as cytokinesis. There are now two complete cells where there used to be one. Cell division occurs in a predictable series of stages or _______________________. These steps make sure that the new daughter cells are the same as the cell from which they formed. Each stage has a name. The first _______________________ actually takes place before cell _______________________ starts. It is called interphase, and is part of the cell cycle but NOT part of mitosis. As a cell prepares to ________________, each chromosome in the nucleus makes a(n) _______________________ copy of itself. This process is called replication. The two copies are called sister _______________________ . If you're looking at cells under a microscope, the individual chromosomes are not visible at this stage. During prophase, the first phase of mitosis, the nucleus prepares for cell division. The genetic material shortens and thickens. With a microscope, you can see the chromosomes. The chromosome copies are held together at their centers by a _______________________, so they look like an X. The nuclear membrane starts to break down. 4 During metaphase, the two copies of each chromosome line up in the center of the cell, called the _______________________ plate. The copies of the chromosomes are attached to protein fibers which form the spindle. During anaphase, the copies separate. One complete set of chromosomes is pulled by the spindle fibers to one side of the cell. The other complete set is pulled to the other side of the cell. A new nuclear membrane forms around each set of sister chromosomes. Telophase is the final stage of cell division. Two groups of chromosomes are now located at opposite ends of the cell. They begin to uncoil and can no longer be seen with a microscope. In animal cells, the cytoplasm pinches in at the center of the cell and the cell membrane squeezes together around the center of the cell, _______________________ the original cell in half. In plant cells, a _______________________ forms across the middle of the cell creating new cell membranes between the daughter cells. When cell division is complete, two new daughter cells are formed. The daughter cells are identical to the __________________ cell. To help you remember the stages of the cell cycle in order, you can remember this: I picked my apples today. The first letter of each word of the phrase begins with the first letter of the phases. I stands for interphase (before mitosis starts), p stands for prophase, m stands for metaphase, a stands for anaphase, and t stands for telophase. 1. What happens when a cell divides? 2. A human body cell with a diploid number of chromosomes has ______. 98.6 chromosomes 46 chromosomes 23 chromosomes 3. Mitosis is ______. Dividing of the nuclear material including genetic material Dividing of cytoplasm Cell division in prokaryotes 4. Chromosomes are replicated or copied in _____. Interphase Metaphase Anaphase 5. What are the four stages of mitosis? Interphase, synthesis, prophase, metaphase Prophase, metaphase, anaphase, and telophase Interphase, metaphase, anaphase, and telophase 6. During metaphase, what happens to the chromosomes? Each copy goes to opposite ends of the cell. Both copies line up across the center of the cell. They are all mixed up and hard to see. 5 7. During telophase, what happens? Two groups of chromosomes line up in the middle of the cell. Spindle fibers pull them apart. Two groups of chromosomes go to opposite ends of the cell. The cytoplasm divides, and two new cells are formed. The cell is growing and replicates or copies its chromosomes. 8. When cell division is complete, what has been formed? Two new sister cells with different chromosomes Two new daughter cells with identical chromosomes Two new sister chromotids CELL CYCLE MINI BOOKLET 6 Meiosis Check off the assignments as you complete them. _____ 1. Read pages 132-133. _____ 2. Complete ‘Art In Motion’ on pages 132 – 133. _____ 4. Obtain an answer key and check the answers on page 93. Correct anything that is wrong, then return the answer key. _____ 5. Answer questions 1, 2, and 3 in the “What Happens During Meiosis” notes that starts on page 13 of this booklet. _____ 6. Obtain an answer key for the notes and check the answers. Correct anything that is wrong, then return the answer key. _____ 7. Complete the Meiosis worksheet starting on page 14 of this booklet. What Happens During Meiosis? (pages 132 – 133) 1. What kind of cells are produced in meiosis? (page 132) 2. What happens during meiosis? (page 132) 3. How many divisions take place during meiosis? (page 133) 7 Meiosis anaphase divide divisions exception necessary organisms reproduction sperm Directions: Fill in each blank with the word that best completes the reading comprehension. Living things reproduce to make more organisms like themselves. When organisms reproduce, many traits of the parents are passed to the new organism. Reproduction is ______________________ for the survival of the species. If _______________________ didn't reproduce, the species would die out. Many organisms reproduce by combining cells from two different parents. This type of reproduction is called sexual reproduction. In sexual _______________________, the offspring receive genetic material from both parents of different sexes. Plants, insects, animals, some fungi, and people all make more of themselves by sexual reproduction. Special cells, sperm and egg cells, are used in sexual reproduction. These cells, called gametes, form by a type of cell division called meiosis. Cells formed through meiosis have only half the number of chromosomes or genetic material of the parent cell. For example, most cells of fruit flies have eight chromosomes, arranged as four similar pairs. But the egg or sperm cells of a fruit fly have only four chromosomes. Humans have forty-six chromosomes, arranged in twenty-three pairs. But human egg and sperm cells only have twenty-three chromosomes. How does this happen? There are two ways cells replicate: mitosis and meiosis. Mitosis is the simple duplication of a cell and all of its parts. It duplicates its DNA and divides, and the two new daughter cells are exactly the same. They have the same genetic code. One cell becomes two cells that are identical. All cells in the human body ____________ in this way-- all except the egg and sperm cells. These cells are different. One egg and one _______________________ cell will join together in a process called fertilization. If each of them carried a full set of chromosomes, fertilization would result in a new organism having twice as many chromosomes as it should have. So for these special cells, there must be two cell _______________________ . This is called meiosis (pronounced my-OH-sis). Remember the cell cycle steps of mitosis? They are prophase, metaphase, _______________________ , and telophase. In meiosis, the cell goes through these steps twice. Scientists call each group meiosis I and meiosis II, but it is basically just two cell divisions. The interphase that happens between the two is very short, and the DNA is not duplicated a second time. Another difference in meiosis and mitosis is that four daughter cells are created from the original cell. Each of the four cells has half the DNA of the parent cell. This is known as a haploid cell. Haploid just means that it has half the regular number of chromosomes. A normal cell with the correct number of chromosomes is called diploid. 8 The process of meiosis allows each new offspring to have different genes from the parents. This process called crossing over mixes up the genes so that the new cells are not duplicates of the parent cell. In fact, with humans having 23 pairs of chromosomes, there are over 8 million combinations possible! This is why children are not exactly like their parents. It also explains why brothers and sisters are never exactly alike. The only _______________________ to this is in the case of identical twins. Identical twins form from one egg cell that has been fertilized by one sperm cell. Because they form from the same 46 chromosomes, 23 from each parent, they do have the same genes. Not all twins are identical. Sometimes twins result from the female releasing two egg cells at the same time. Each egg cell has different genes, and each egg cell is fertilized by two different sperm cells, also having different genes. These twins are called fraternal. They may look no more alike than any other set of siblings. Fraternal twins can be the same sex, or they can be the opposite sex. Identical twins, however, are always the same sex. 1. Which kinds of cells take part in sexual reproduction? Brain and body cells Skin and heart cells Egg and sperm cells 2. What are gametes? Skin and heart cells Egg and sperm cells Brain and body cells 3. All cells in the human body, except egg and sperm cells, duplicate by: Meiosis Sexual reproduction Fission Mitosis 4. Egg and sperm cells duplicate by: Mitosis Meiosis Fission 5. Mitosis results in: Two cells with identical genes Four cells with different genes Four cells with identical genes Two cells with different genes 6. Meiosis results in: Two cells with different genes Four cells with identical genes Four cells with different genes Two cells with identical genes 9 7. Diploid cells have: Half the chromosomes of the parent organism Twice the number of chromosomes of the parent organism The regular number of chromosomes of the parent organism 8. Haploid cells have: Half the chromosomes of the parent organism Twice the number of chromosomes of the parent organism The regular number of chromosomes of the parent organism 10 VOCABULARY MEIOSIS chromatid - one-half of two identical copies of a replicated chromosome chromosome - A chromosome is a long, stringy collection of genes that carries heredity information (DNA) and is formed from condensed chromatin. centromere - region on a chromosome that joins two sister chromatids. ______________________ ______________________ ______________________ ______________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ___________________________ ___________________________ ___________________________ _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ 11 _______________________ CELL DIVISION WEBQUEST PART 1 The Cell Cycle Go to http://www.cellsalive.com/ Click on “Mitosis” under the picture labeled “Interactive Eukaryote Cell Cycle.” Read the text on this page. You may have to scroll down to see it. Complete the chart below. Which stage does the following occur? EVENT STAGE Chromatin condenses into chromosomes Chromosomes align in center of cell Longest part of the cell cycle Nuclear envelope breaks down Cell is cleaved into two new daughter cells Daughter chromosomes arrive at the poles Click on the read box at the top, left of the page that says “Start the Animation.” View the animation. Watch it carefully. You can slow down the video by clicking the button, and moving step by step through the phases. The colored chromosomes represent chromatids. There are two of each color because one is an exact duplicate of the other. How many chromosomes are visible at the beginning of mitosis? ________________ How many are in each daughter cell at the end of mitosis? __________________ The little green T shaped things on the cell are _________________. 12 What happens to the centrioles during mitosis? Identify the stages of these cells: ___________________ _________________ ___________________ __________________ 13 Part 2 Mitosis: The Amazing Cell Process That Uses Division to Multiply Go to the following website and watch the video: https://www.youtube.com/watch?v=gwcwSZIfKlM Amoeba Sisters Video Recap of Mitosis: The Amazing Cell Process That Uses Division to Multiply Mitosis is done by your body cells. This cartoon illustrates an exception. What type of cells do NOT undergo mitosis? Describe how mitosis is important for your body. _____________________ ____________________ _____________________ ____________________ _____________________ ____________________ _____________________ _____________________ This illustration is trying to demonstrate something that mitosis is not. In mitosis, the cells that are created are ____________________. Mitosis is just one small part of the cell cycle! Describe what would occur if cells were in mitosis more than they were in interphase. ____________________ ____________________ ____________________ ____________________ 14 ____________________ Then cells are dividing, it is important to understand that they have to move chromosomes equally to both cells. Based on this illustration, describe what a chromosome is made of. Mitosis starts and ends with diploid cells. That means they have two sets of chromosomes (both parents each contribute a set). In humans, how many chromosomes should be in each of the diploid cells after mitosis? ________________ _________________ ________________ ________________ 15 Sketch the Mitotic Stages Directions: Sketch the mitotic stages. Label the chromosomes, spindles, and nucleus where applicable. Prophase Metaphase Anaphase Telophase 16 Part 3 Onion Root Tip Go to http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html Read the introduction, then click the “next” button. Study the pictures of each stage of the cell cycle, then click the “next” button. A small cell will appear, click on the phase where you think it belongs. You will have 36 cells to classify. When you’re finished, record your data in the chart below. Interphase Prophase Metaphase Anaphase Telophase Total Number of cells 36 Percent of cells* 100% *To calculate percent: number of cells divided by total cells (36) x 100 Part 4 Virtual Cell Animation Go to: http://vcell.ndsu.nodak.edu/animations/meiosis/first.htm 1. What happens to the DNA during prophase I? _______________________________________ _______________________________________ 2. What happens with the homologous chromosomes during prophase I? _______________________________________ _______________________________________ _______________________________________ This is called c __ __ __ __ __ __ __ o __ __ __ 3. What happens to the connected chromosomes during metaphase I? _______________________________________ _______________________________________ _______________________________________ What is an easy way to remember this? (Hint: It has to do with the first letter of metaphase.) _______________________________________ _______________________________________ _______________________________________ _______________________________________ 17 4. Draw, IN COLOR, picture 4 in the space below, paying very close attention to the colors of the chromosomes. How do the chromosomes in picture 4 differ from the chromosomes in picture 1? _______________________________________ _______________________________________ _______________________________________ _______________________________________ When did this change occur? (Hint: Look at the right side of picture 2.) _______________________________________ _______________________________________ 5. What happens during anaphase I? ___________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ 6. What happens during telophase I? ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ 18 7. What happens during prophase II? ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ 8. What happens during metaphase II? ____________________________________ ____________________________________ ____________________________________ ____________________________________ 9. What happens during anaphase II? ____________________________________ ____________________________________ ____________________________________ ____________________________________ 10. What does elongate mean? (Hint: Google it.) _______________________________________ _______________________________________ 11. What happens during telophase II? ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ 12. How many new cells are formed during meiosis? ______________________________ 13. What are gametes? (Hint: Google it.) _______________________________________ _______________________________________ 19 Part 5 Meiosis: The Great Divide Go to https://www.youtube.com/watch?v=toWK0fIyFlY Amoeba Sisters Video Recap of Meiosis: The Great Divide The purpose of meiosis is to make gametes, also known as sperm and egg cells. In humans, your body cells have 46 chromosomes. How many chromosomes are in a sperm or egg cell if, when they come together to form a fertilized zygote, there are 46 chromosomes? Write the correct number of chromosomes next to the sperm and egg. Interphase must occur once before meiosis can happen. (Same thing for mitosis.) What would happen if interphase didn’t occur first? Remember that a cell begins meiosis with 23 chromosomes inherited from mother and 23 chromosomes inherited from father. In the process of meiosis, chromosomes begin to match up in homologous pairs. How would you know if two chromosomes were homologous? Crossing over is a very important event on Prophase I of meiosis! What happens during crossing over and what is the significance? 20 Meiosis does PMAT twice! That means there is a prophase 1 and a prophase 2. There is a metaphase 1 and a metaphase 2, and so on. If the cartoon below has chromosomes in the middle of the cell, how would you know whether it was in metaphase 1 or metaphase 2? Meiosis does not always occur without any difficulties. Describe what occurs during nondisjunction and the effect on the resulting cells. 21 Keeping mitosis and meiosis in your mind can be a bit tricky. Read the information in the boxes below. Determine whether they would be correctly place in the mitosis video, the meiosis video, or both. Write the corresponding number in the proper place in the Venn diagram. 1 Interphase occurs only once before the process begins. 4 Produces 4 cell that each have 23 chromosomes for humans. 2 Process ends with identical cells. 5 Crossing over occurs 3 Produces gametes. 6 Process is important for growth and repair Mitosis Meiosis 22 Part 6 PBS: Mitosis vs. Meiosis Go to http://www.pbs.org/wgbh/nova/baby/ Click on "How Cells Divide" then “Launch Interactive” (NOTE: If the Interactive does not work, click on “Printable Version”) After viewing the animation, fill out the chart below, by placing a check in the box or boxes to indicate which the event occurs in (some events might have checks for both mitosis and meiosis). Meiosis Mitosis Two cell divisions Centrioles appear Chromosomes pair up Spindle fibers form Two cell divisions Cytokinesis Four daughter cells Cell Division Review Use the information in this booklet or your textbook (pages 92-99) to answer the following questions. Phases of Mitosis Phase Event 1. Prophase Chromosomes attach to the spindle fibers. 2. 3. Anaphase 4. New nuclear envelope forms 23 5. Which stage of the cell cycle usually lasts the longest? ________________ 6. During which stage of the cell cycle does DNA replication occur? _________ 7. During which stage of the cell cycle does the cell membrane pinch the cell into two? ____________ Mitosis and Meiosis Word Scramble Scrambled Word istmosi eisisom seetgma Clue Process in of cell division, one cell turns into two cells Process in which one cell divides into four sex cells Answer Sex cells Region where sister chromatids are attached in a chromosome rtreonecme clceeycll nipesld sonyteeicks Process in which cells grow and reproduce (2 words) Fibers that attach to the chromosomes during mitosis or meiosis Stage in which the dividing cell splits into two new cells 24 CELL DIVISION C A N C E R V O L U M S T E M Across 4. Series of events a cell goes through as it grows and divides; the cell ___ 6. The phase in which DNA copies itself 8. Holds sister chromatids together 9. When a cell divides, it forms two ___ cells 10. Cells that can become any other cell type; ___ cells 11. Division of the cell nucleus 13. The phase where cytokinesis begins 15. The phase where chromosomes line up along the equator Down 1. Division of the cytoplasm 2. Structure made of fibers that help to move chromosomes during mitosis 3. A chromosome consists of two identical ____ 5. Disease caused by uncontrolled cell growth 7. Cells are limited in size by their surface areas and ____ 8. Paired structure that helps to organize the spindle 12. Cells exchange materials across the cell ____ 14. The phase where chromatids separate 16. The phase where chromosomes first become visible 25 CELL DIVISION “REVIEW AND REINFORCEMENT” You may use your textbook and notes to complete this review DIRECTIONS 1-4: Injured and old, worn-out cells in your body are constantly being replaced by new cells. New cells are produced by the processes of mitosis and cell division. Study the four stages of mitosis shown in the pictures. Number the stages in the order in which they occur. Match the names of the stages below with their descriptions. Then answer the questions. DIRECTIONS 5-8: Label the name of each stage above. DIRECTIONS 9-13: Use the word bank bold faced and italicized below to put the best letter in each blank A. prophase C. anaphase B. metaphase D. telophase ______9. The doubled chromosomes separate. Single chromosomes move to opposite ends of the spindle. ______10. Doubled chromosomes form, the nuclear envelope disappears, and the spindle forms. ______11. The cell divides in two. ______12. The spindle disappears. A nuclear envelope forms around each set of chromosomes. ______13. Doubled chromosomes line up in the middle of the spindle. 26 DIRECTIONS 14-25: Use your understanding of cell division to address each of the following 14. In what stage is a cell before mitosis begins? _____________________________________________ 15. What takes place in the cell during this stage? _____________________________________________ _____________________________________________ _____________________________________________ 16. What process occurs as mitosis ends? _____________________________________________ 17. How does the cell cycle differ in animal cells and plant cells? _____________________________________________ _____________________________________________ _____________________________________________ _____________________________________________ 18. Why is the process of mitosis an important part of the cell cycle? _____________________________________________ _____________________________________________ _____________________________________________ _____________________________________________ 19. Write a saying that will help you remember the stages of Mitosis in order. For example, Pass Me A Tissue. (You may NOT use the example!!!) _____________________________________________ ___________________________________________________________________________ ____________________________________________________________ 27 20. Write the names of the stages of the entire cell cycle in the correct order below: ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ 21. IN YOUR OWN WORDS, define the words cell division: ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 22. What is the name given to the original cell before it divides? ____________________ 23. The two cells formed due to cell division are called ____________________. 24. Mitosis is a form of ____________________ reproduction. 25. The parent cell is ____________________ to the daughter cells. 28