Week 3 Experiment

WEEK 4 EXPERIMENT ANSWER SHEET Please submit to the Week 4 Experiment dropbox no later than Sunday midnight. SUMMARY OF ACTIVITIES FOR WEEK 4 EXPERIMENT ASSIGNMENT  Experiment 4 Exercise 1 –Mitosis in a Plant Cell  Experiment 4 Exercise 2 – Meiosis  Experiment 4 Exercise 3 – Karyotyping Experiment 4 Exercise 1: Mitosis in a Plant Cell Read through the Experiment 4 Introduction material before starting. In this exercise we will look at the different stages of mitosis in onion cells. The length of the cell cycle in the onion root tip is about 24 hours , but mitosis only occupies only one to two hours. Procedure A. Review the information on p 125 in your book and record your predictions as to the percentage of cells you expect to see in each of the phases of the cell cycle in Table 1 (after the photographs). B. In the four photographs below, examine each cell indicated by a red dot. There are a total of 65 cells that need to be examined. Determine how many cells are in the various stages of the Cell Cycle . Refer to your book and the Experiment 4 Introduction information for help determining the cell cycle stages. C. Enter your data in Table 1 . Note that the “Calculated %” is equal to the Number of cells in stage / Total cells counted x 100. D. Answer the questions that follow.

Table 1: Predictions and actual number of cells observed in each stage of the cell cycle (2 pts) Stage Predicted % Number of Cells Total Cells Counted Calculated % Interphase 7 0 4 5 65 69.2 Prophase 1 2 5 65 7.7 Metaphase 8 6 65 9.2 Anaphase 5 4 65 6.2 Telophase 5 5 65 7.7 Total 100% 65 65 100% Questions 1. What stage of the cell cycle were most of the onion root tip cells in (1 pts)? Most of the onion root tip cells were in the interphase stage. Is this what you would expect based on what you’ve read this week; why or why not? Cite source(s) used (1 pts) . “Interphase lasts for at least 90% of the cell cycle”. ( Simon, E.J., J.L. Dickey and J.B. Reece. 2013. Campbell Essential Biology, 5th Edition. Pearson: Boston) 2. How accurate were your predictions, based on your data, for each stage of the cell cycle (1 pts)? I think my predictions were accurate, due to the fact that the interphase makes up the majority of the cell cycle. 3. What is the function of mitosis in an organism such as a human? Cite source(s) used (2 pts) . The function of mitosis in an organism such as a human is to divide cells to produce more essential cells to be able to heal and grow (Meister, 2016). Experiment 4 Exercise 2: Meiosis Review this week’s reading in your book (pp 131-141) and this week’s online lecture. Then view the following animation before answering the questions below; be sure your audio is on: McGraw-Hill Higher Education. 2006. How Meiosis Works http://highered.mcgraw-

hill.com/sites/0072495855/student_view0/chapter28/animation__how_meiosis_ works.html Questions 1. Why is it necessary to reduce the chromosome number in gamete cells (egg and sperm), but not other cells of an organism? Cite source(s) used (2 pts) . It is very important to reduce the chromosomes number in gamete cells because it prevents a zygote from having too many chromosomes. If both parents were to put all of their chromosomes, 46 form the father and 46 from the mother in their egg and sperm – this would lead to failed for a zygote to become a person. A person needs only 46 chromosomes, and half (23) come from each parent to achieve the needed number. (Simon, E.J., J.L. Dickey and J.B. Reece. 2013. Campbell Essential Biology, 5th Edition. Pearson: Boston) 1. Describe at least two differences between Meiosis I and Meiosis II in terms of what is produced and what occurs with the chromosomes . Cite source(s) used (2 pts) . Meiosis I – Makes recombination in the daughter cells. Includes 4 phases (prophase, metaphase, anaphase, telophase) Meiosis II – Is the division of Meiosis I. The splitting of the cell in half is the result of meiosis II. 2. If humans have 46 chromosomes in each of their body cells, determine how many chromosomes you would expect to find in the following cells (4 pts): Sperm 23 Liver cell 23 Daughter cell from mitosis 46 Daughter cell from Meiosis II 46 3. _____ are separated during Meiosis I, while _____ are separated during Meiosis II (2 pts). a. Sister chromatids, sex chromosomes

Chromosome Presented Matches # Chromosome a 2 Chromosome b 16 Chromosome c 12 Chromosome d 5 Chromosome e 21 Questions 1. What notation would you use to characterize Patient A's karyotype? Be sure to read over the information presented so you know the correct notation format (1 pts). 47, +21, XX 2. Based on the table of possible chromosomal disorders displayed on the website, what diagnosis would you give patient A (1 pts)? Down syndrome. 3. When during Meiosis does the error occur that results in this karyotype; be specific (1 pts)? During nondisjunction . Procedure (continued) E. Click on the Patient History button (bottom of the page) and then click on Complete Patient B’s Karyotype . F. Match the chromosomes presented as done in the previous exercise. G. Fill in the Table 3 below, indicating how you matched up the chromosomes presented with the actual chromosomes in the karyotype. Table 3 . Patient B karyotype data (1 pts). Chromosome Presented Matches # Chromosome a 21

Chromosome b 11 Chromosome c 14 Chromosome d XX/XY Chromosome e 3 Chromosome f 20 Chromosome g 10 Chromosome h (This is a tough one) XXY Questions 4. What notation would you use to characterize Patient B's karyotype (1 pts)? Male, 47 chromosomes, and an extra sex chromosome. 5. What diagnosis would you give patient B (1 pts)? Klinefelter’s syndrome. Why does this individual exhibit male characteristics and not female? Cite your source (2 pts) . Klinefelter Syndrome is the result of an extra X chromosome in males. A sex trisomy, instead of XY males instead have XXY chromosome. Females are XX. Procedure (continued) H. Click on the Patient History button (at the bottom) and then click on Complete Patient C’s Karyotype . I. Match the chromosomes presented as done in the previous exercise. J. Fill in Table 4 below, indicating how you matched up the chromosomes presented with the actual chromosomes in the karyotype. Table 4 . Patient C karyotype data (2 pts). Chromosome Presented Matches # Chromosome a 12 Chromosome b 3 Chromosome c 11