Mitosis and Meiosis: Key Concepts and Observations in BIO201L

Lab 3 Mitosis and Meiosis BIO201L Student Name: Narek Hakobyan Access Code (located on the lid of your lab kit): AC-NFDQUK Lab Report Format Expectations Utilize college level grammar and professional formatting when completing this worksheet. Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre- lab Questions 1. What are chromosomes made of? Long Strands of Double Helix DNA 2. Compare and contrast mitosis and meiosis, ensuring to detail the differences in both function and in process . ( Hint : Your response should be 4-5 sentences long.) Meiosis happens in plants, animals, and fungi, but not in viruses. Mitosis happens in all other living things. Meiosis and mitosis both copy DNA and have a diploid number of chromosomes. However, during meiosis, the copying changes to a haplioid number of chromosomes. 3. Cancer is a disease related to uncontrolled cell division. Investigate two known causes for these rapidly dividing cells and use this knowledge to invent a drug that would inhibit the growth of cancer cells. ( Hint : Your response should be 4-5 sentences long.) Mutations in genes and changes in the environment are known to cause cancer cells to divide quickly. The growth would be slowed down by a drug called Akousua.

Lab 3 Mitosis and Meiosis BIO201L EXPERIMENT 1: OBSERVATION OF MITOSIS IN A PLANT CELL Introduction Questions 1. State how you will calculate the number of hours each stage of mitosis takes based on observations. Do so by either stating the “Hours of Stage” equation, or by discussing the equation and its application. If you decide to insert an equation, you must use an equation editor to properly state the equation with the correct symbols and fraction format. Click here to enter text. 2. In Table 1, below, predict how many hours of the 24-hour cell cycle you think each step takes. Ensure you provide robust supporting evidence to back your prediction. Table 1: Mitosis Predictions Predictions Interphase will be the longest at 19 hours and Mitosis will only take up 5 hours Supporting Evidence Interphase takes the longest so majority of the time will be in the interphase stage.

Lab 3 Mitosis and Meiosis BIO201L Data and Observations Record your observations in the table below. Based on those observations, calculate the percentage of time spent in each phase of mitosis. Table 2: Mitosis Data Chosen Image Onion Root Picture Stage Number of Cells in Stage Total Number of Cells Calculated % of Time Spent in Stage Interphase 20 38 52% Prophase 10 38 26% Metaphase 3 38 7% Anaphase 2 38 5% Telophase 1 38 2% Cytokinesis 2 38 5%

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Lab 3 Mitosis and Meiosis BIO201L Below, insert the drawings you generated of each phase of mitosis. You must include your handwritten name in the background. Submissions that do not meet this requirement will be rejected. Table 3: Stage Drawings Cell Stage Drawing Cell Stage Drawing Interphase Anaphase Prophase Telophase Metaphase Cytokinesis

Lab 3 Mitosis and Meiosis BIO201L Results and Discussion 1. Label the arrows in the slide image below with the appropriate stage of the cell cycle. A. Interphase B. Telophase C. Interphase D. Cytokinesis E. Prophase F. Anaphase

Lab 3 Mitosis and Meiosis BIO201L 2. What stage were most of the onion root tip cells in? Based on this observation, explain why this is to be expected. Most of the Cells are in interphase, and this makes sense since it is the longest phase during cell division 3. As a cell grows, what happens to its surface area : volume ratio? (Think of a balloon being blown up). How is this changing ratio related to cell division? This is because the ratio goes down when a cell divides because the cell surface is cut in half. It makes sense that as a cell gets bigger, the ratio goes up. 4. What is the function of mitosis in a cell that is about to divide? Mitosis divides chromosomes between two cells evenly to get identical results 5. What would happen if mitosis were uncontrolled? To many news cells would be produced and the cells would not have time to preform their own functions. 6. How accurate were your time predictions for each stage of the cell cycle? I was partially correct in stating which phase is going to take the longest 7. Discuss one observation that you found interesting while looking at the onion root tip cells. The most interesting phase is the Anaphase phase, where you can see the actual cell division

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Lab 3 Mitosis and Meiosis BIO201L EXPERIMENT 2: TRACKING CHROMOSOMES THROUGH MITOSIS Introduction Questions 1. Cite an example of a type of cell that undergoes mitosis. Why is it important for each daughter cell to contain information identical to the parent cell? If a cell is not identical to the parent cell, the DNA sequence is altered. If not corrected by the body the problem can become bigger problem in some cases the cause of cancers 2. Hypothesize what would happen if the sister chromatids did not split equally during anaphase of mitosis. The Cells would not be Identical and a mutation will accur. 3. Human skin cells divide at a higher rate than neurons (nerve cells). Hypothesize why this may be. Skin cell cycles are much faster because mitosis is frequently accuring. On the other hand were nerve cells are in the interphase for decades because of that they do not divide.

Lab 3 Mitosis and Meiosis BIO201L Data and Observations Once you have completed the digital exercise, select the “Results Table” button at the bottom right- hand corner of the screen and select the “Generate PDF” button at the top of the following screen. Insert your download into this document by selecting the Insert > Object > Text from file. Resize if necessary.

Lab 3 Mitosis and Meiosis BIO201L Results and Discussion 1. How many chromosomes were present before mitosis? 46 2. How many chromosomes did each of the daughter cells contain after mitosis? 23

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Lab 3 Mitosis and Meiosis BIO201L EXPERIMENT 3: FOLLOWING CHROMOSOMAL DNA MOVEMENT THROUGH MEIOSIS Introduction Questions 1. List two differences between meiosis I and meiosis II. In meiosis I homologous chromosomes divides and in meiosis II sister chromatids separate. Meiosis II seperates the haploid cells to for a total of 4 cells. 2. Why is it necessary to reduce the number of chromosomes in gametes, but not in other cells? Meiosis copies the chromosomes and then divides them twice, making four daughter gamete cells that each have half as many chromosomes as the parent. During fertilization, two gametes come together, and the number of chromosomes they have will be the same from each parent, so the number of chromosomes in the gametes needs to be lowered so that they have the same number as the parents. 3. What is the ploidy of the daughter cells at the end of meiosis I? What about at the end of meiosis II? Two and Four

Lab 3 Mitosis and Meiosis BIO201L Data and Observations Once you have completed Part 1 of the digital exercise, take screenshots and insert them below. Resize if necessary. Table 5a (Meiosis I):

Lab 3 Mitosis and Meiosis BIO201L Table 5b (Meiosis II):

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Lab 3 Mitosis and Meiosis BIO201L Once you have completed parts 2, 3, and 4, select the “View Data Table” button at the bottom left-hand corner of the home screen. Review your table. If you would like to make any changes, select the “Return” button in the bottom right-hand corner. If you are satisfied with your answers, take a screenshot and insert it below. Resize if necessary:

Lab 3 Mitosis and Meiosis BIO201L Results and Discussion 1. How did crossing over affect the genetic content in the gametes? Use your results to support your answer. A new combination of gene sequences 2. Based on your observations in the digital exercise, what can you conclude about the severity of nondisjunction that occurs in meiosis I as opposed to meiosis II? The seriousness is high because of the damage they do to the body, such as copying or losing whole chromosomes. 3. Blue whales have 44 chromosomes in every cell. Determine how many chromosomes you would expect to find in the following: a. Sperm Cell: 22 b. Egg Cell: 22 c. Daughter Cell from Mitosis: 44 d. Daughter Cell from Meiosis II: 22

Lab 3 Mitosis and Meiosis BIO201L EXPERIMENT 4: THE IMPORTANCE OF CELL CYCLE CONTROL Introduction Questions 1. In this experiment, you will review some of the karyotypic differences that can be observed when comparing normal, controlled cell growth and abnormal, uncontrolled cell growth. What is a karyotype? Give the definition below. A karyotype is the full set of an organism's chromosomes, which are usually shown in a structured way, usually paired up based on size, shape, and other factors. This picture shows a quick look at a person's chromosomes and can be used to find genetic problems, figure out a person's sex, or study the shape and amount of chromosomes. Karyotypes are useful in genetics and medicine because they help researchers and doctors figure out what genetic diseases and conditions people have.. 2. Why do cells which lack cell cycle control exhibit karyotypes which look physically different from cells with normal cell cycle. They look different because there are no checkpoints outside of them. There are no rules in place to make sure they are reproducing properly. 3. Record your hypothesis from Step 1 in the Procedure section here. Since cancer cells don't go through interphase, I would expect to see a lot of changes that make the lengths look shorter or more uneven. 4. What are HeLa cells? Why are HeLa cells appropriate for this experiment? A certain kind of cell growth is used in lab research. It is a line of eternal human cells that were made from cervical cancer cells. This is a good topic to study to show what can happen when cell cycle control isn't working right and changes happen..

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Lab 3 Mitosis and Meiosis BIO201L Data and Observations 1. Below, write a paragraph or paragraphs that detail(s) the observations you made during your research. To earn credit, describe the images you viewed, where you obtained them, and the differences you noted between the normal and abnormal karyotypes. ( Hint : Your response must be thorough and will likely contain around 6-10 sentences.) You may include copies of the photos you reviewed, but these are not required for credit and will not be graded. In a standard karyotype, chromosomes are usually placed in pairs. Humans have 46 chromosomes, which are ordered in 23 pairs. There are two sets of sex chromosomes (XX for females and XY for men) and 22 sets of non-sex chromosomes, or autosomes. A normal karyotype shows that the chromosomes are physically whole, with no big losses, duplications, translocations, or inversions. Changes in the amount or shape of chromosomes can cause karyotypes that aren't normal, which can lead to genetic diseases or conditions.Chromosome number changes can be caused by aneuploidy (like trisomy 21 in Down syndrome, where there is an extra chromosome 21) or monosomy (like Turner syndrome in women, where there is only one X chromosome).To sum up, normal karyotypes show how a healthy person's chromosomes are usually arranged, while abnormal karyotypes show changes from this pattern, which are usually linked to genetic illnesses and structural chromosomal abnormalities. Keeping an eye on karyotypes is a very important part of genetics and clinical medicine for finding genetic diseases and understanding them.

Lab 3 Mitosis and Meiosis BIO201L Results and Discussion 1. What do your results indicate about cell cycle control? Cells continue to rapidly divide, which in turn can cause physical changes in the karyotype 2. Research the function of the protein called p53. What does this function do? Explain how it can affect cell cycle control. In the G1 to S transition, the cell cycle stops because of the p53-dependent production of the CDKs inhibitor or (CDC). It takes time to fix DNA damage during this "pause" in the cell cycle. 3. What is the Philadelphia chromosome? How is this chromosome related to cancer? Identify how this chromosome appears physically different on a karyotype than it appears on a karyotype of normal chromosomes. chromosome 22 has a problem or mutation. This happens when chromosomes 9 and 22 break apart and proteins are swapped. This has to do with cancer because chromosomes 9 and 22 are linked to chronic myeloid leukemia. The tail on chromosome 9 is usually longer than it should be, and the tail on chromosome 22 is usually shorter than it should be. This change in shape is because each chromosome broke and switched places. 4. Suppose a person developed a mutation in a somatic cell which diminishes the performance of the body’s natural cell cycle control proteins. This mutation resulted in cancer, but was effectively treated with a cocktail of cancer-fighting techniques. Is it possible for this person’s future children to inherit this cancer-causing mutation? Be specific when you explain why or why not. Somatic cells cannot be passed down from parent to child, only genetic makeup can be passed down from parent to child.

BIO201 Lab 3

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