Lab+7.++Cell+Division+exercise+using+socks+as+chromosomes+2020

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Dec 6, 2023

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1) At some points during a cell’s life, its genetic material is “unraveled” and diffuse (see Cell A below). At other points during times during a cell’s life, its genetic material becomes compacted so that you can see individual chromosomes (see Cell B below). a) Which of the above cells shows what the genetic material looks like during interphase ? Cell A OR Cell B b) In your own words, briefly describe what cells are doing during interphase. In other words, what’s the purpose of interphase? During interface, so gross and creates the structure of proteins. I can repair the damage porch in transports, nutrients, eliminates waste, as well as prepare for my ptosis by building proteins. c) In your own words, briefly describe what cells are doing during mitotic phase. In other words, what’s the purpose of mitotic phase? The purpose of mitotic phase is to create two identical daughter cells from the original one. It contains four stages them being prophase, metaphase, anaphase, and telophase. d) Consider the time period that starts when a cell is “born” and ends when the cell divides. Approximately what percentage of this time is devoted to interphase? About 95% of the time it’s about it’s interphase e) Say that you look at the nuclei of 100 skin cells taken from the same person. About how many of these skin cells would you expect to be in interphase? I would expect her about 90% of the skin cells to be in interphase f) Think about a group of cells that are undergoing very frequent cell divisions (e.g. cells that are part of a growing embryo). Suppose that you looked at 100 of these cells. How many of these cells would you expect to be in interphase? Circle your answer . More than the number from part e OR Less than the number from part e g) Explain your answer to part f. 1 Pre-Lab Questions for Cell Division exercise using socks A B

More cells are in mitotic phase because they’re actively dividing which means they spend less time in inter-phase, and spend more time in the mitotic phase 2) In your own words, explain the difference between mitosis and meiosis (focus more on the final results, instead of the details of each individual subphase). It’s less than the number from part E, because after mitosis, two cells are formed, and all of them have the exact same genetics, and after meiosis cells are formed and their genetics it’s only half of their parents 3) How are mitosis and meiosis similar? Both of these have the same stages of cell division ACTIVITY #1: CELL DIVISION SIMULATION Introduction The purpose of this activity is to reinforce the major concepts discussed during lecture/seminar regarding cell division. See if you can work through this activity using what you remember from class. Use your textbook (or other resources) only as a last resort. Materials •Six pairs of socks that are all different colors (or at least identifiable as pairs) and four long pieces of string. Procedure 1) Take 6 pairs of socks out of your drawer. Do your best to select them such that you have two of each pair (it is even better if they each pair of sock pairs is similar but different, representing homologous chromosomes from each parent). This is 12 socks total, and there should be 4 of each type. Each sock will represent a single chromosome (or a single chromatid/copy of a chromosome). Keep in mind that in some phases of the cell cycle, sister chromatids/copies are attached to each other. The heel of each sock will represent the centromere. 2) Separate them into two equal piles (one sock from each pair in each pile). One pile will represent the genome of an organism that has a diploid number of 6. Humans have a diploid number of 46 (2x23). (the other pile will be used to demonstrate what they look like after DNA replication has occurred during the cell cycle). 2

3) Assuming that the cell has a diploid number of 6 (2N = 6), lay-out the chromosomes showing how the cell would look before S-phase has taken place with a piece of string around them in a circle to represent the nuclear membrane. Q1: How many single chromosomes do you see? Take a picture and insert it here: 6 4) Now demonstrate what this organism’s chromosomes would look like after S phase but before Mitosis begins. This is where the other pile of socks are required. Q2: When do you see sister chromatids (circle one)? Before S-Phase After S-Phase Before and After S- Phase Take a picture and insert it here: 5) Show how this organism’s chromosomes would LINE UP with each other during Metaphase of MITOSIS. Q3: Are sister chromatids attached to each other at this point? Why or why not? Take a picture and insert it here: yes, because chromatids are attached in homologous chromosomes are paired up Q4: Are homologous chromosomes paired with each other at this point? Why or why not? Yes, homologous chromosomes are paired up with each other Now pull apart the chromosomes to opposite sides of your bed to show how they separate during MITOSIS (Anaphase and Telophase). Use string to draw in the nuclear envelopes and cell membranes surrounding each set of new chromosomes. Each of the cells you drew in represents a daughter cell containing their new set of chromosomes. Take a picture and insert it here: Q5: Are sister chromatids attached to each other at this point? Why or why not? yes, sister chromatids are attached to each other this point 6) After step #5, you should now have two cells, one on either side of your bed. 3

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Q6: How many chromosomes does each of the daughter cells have? Each of the daughter cells have four chromosomes Q7: How does this number compare to the number of chromosomes in the original parent cell? It is equal to half of its parent cell Q8: Would you consider the daughter cells to be diploid or haploid? I would consider the daughter cells to be haploid Q9: Are these daughter cells more likely to be skin cells or sperm cells? Explain your answer. These daughter cells are more likely to be sperm cells Next, we’ll have you work through the process of meiosis. But before we do that, answer Q10-Q12 below: Q10 : Homologous chromosomes typically have… BOLD all that apply i. the same genes. ii. the same number of genes. iii. the same exact combination of genes (i.e. the exact same alleles) iv. roughly the same size. Q11 : Sister chromatids typically have… BOLD all that apply i. the same genes. ii. the same number of genes. iii. the same exact combination of genes (i.e. the same alleles) iv. roughly the same size. Q12: Is it possible for homologous chromosomes to have different alleles? Yes or No Now, we’ll work through what occurs during meiosis. 7) Now simply take two socks from similar pairs, but not the same pair. These two socks represent one chromosome from each parent. Q13: These two chromosomes be called…( circle one ) Homologous Chromosomes or Sister Chromatids 4

Q14 : These two chromosomes are the same size, but if each original pair of socks had been worn differently, these two socks would looks similar but different. Would you assume that each chromosome has the same general organization? In other words to they contain the same types of genes? Yes or No Q15 : If you answered “ Yes ” to the previous question, is it possible that this type of trait (brown, blue, etc.) is exactly the same on each chromosome? Explain your answer. If you answered “ No ” to the previous question, explain your reasoning. it is not possible that these type of tree is exactly the same when each chromosome because the genes contain allele , which foods follow a dominant relation, which one would be dominant, while the other one is recessive Q16 : Is it possible for homologous chromosomes to have any of the same alleles on them? Explain your answer. No, because each Málaga Spear is from different individuals 8) Now arrange all 12 socks to show how this organism’s chromosomes would PAIR UP with each other during Prophase I of MEIOSIS I. You should try to illustrate what crossing over looks like at this stage of Meiosis. Take a picture and insert it here: Q17: Crossing over occurs between… circle your answer i. One chromatid and its sister chromatid ii. One chromosome and its homologous chromosome Q18: In your own words, briefly describe what crossing over is. Crossing over means the exchange of chromosomes between nonsister chromatids during the production of gametes 5

9) Now arrange the chromosomes to show how they will align during Metaphase I of MEIOSIS I. Take a picture and insert it here: Q19: Are sister chromatids attached to each other at this point? If so, draw and label a pair of sister chromatids in the space below. If not, then explain why not. Yes, because your first two identical copies, which were made by DNA replication of a chromosome Q20: Are homologous chromosomes paired with each other at this point? Why or why not? Yes, I’m like is chromosomes paired with each other at this point, because the pair of chromosomes align on either side of the equationql of plate 10) Now pull apart the chromosomes to opposite sides of your bed to show how they separate during MEIOSIS I (simulate Anaphase I and Telophase I). Take a picture and insert it here: Q21: Are sister chromatids attached to each other at this point? If so, draw and label a pair of sister chromatids in the space below. If not, then explain why not. Yes Q22: Are homologous chromosomes paired with each other at this point? If so, draw and label a pair of homologous chromosomes in the space below. If not, then explain why not. No, because homologous chromosomes are separate in anaphase in which sister chromatids remain attached is 11) Now pull apart the chromosomes to show how they separate during MEIOSIS II (simulate Metaphase, Anaphase and Telophase of the second part of Meiosis). Use strings to draw the membranes around the daughter cells. Take a picture and insert it here: 6

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Q23: Are sister chromatids attached to each other at this point? Yes or No Q24 : At the end of MEIOSIS, you should be looking at 4 sets of chromosomes arranged on different sides of your bed. Each of these chromosome sets will be incorporated into new daughter cells. Q25: How many chromosomes does each of the daughter cells have? each of the daughter cells have half of the mother cell Q26: How does this number compare to the number of chromosomes in the original parent cell? The chromosomes in the original parent so it’s half of its parents cell Q27: Do all of the daughter cells have the exact same set of alleles? No Q28: Would you consider these daughter cells to be diploid or haploid? Haploid Q29: Are these daughter cells more likely to be skin cells or sperm cells? Explain your answer. The daughter cells are more likely to be sperm cells 12) If you joined one of the cells from the end of Meiosis II with a similar cell from another student in the class…… Q31: How many total chromosomes do you have after you mixed together the two sets? After mixed together, the two sets there are six chromosomes Q32: Is this a diploid number or a haploid number of chromosomes? It’s a diploid number of Q33: The chromosome mixing you’ve just performed represents which of the following? a) A skin cell dividing b) The formation of a birth defect c) The fertilization of an egg 7

Lab+7.++Cell+Division+exercise+using+socks+as+chromosomes+2020

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