(3rd ed.) Page 1 BIO 100 LAB SIGN OFF PAGE - UNIT 5 Name ___________________________ Please staple all of your lab pages for this Unit together with this page as the top. You will use this page to get your Labs for Unit 5 signed off by the Biology Learning Center staff. You need to have all of the following steps initialed by a staff member before you will be allowed to take the Unit 5 Exam. After you have obtained all of your sign offs for this Unit, be sure that a BLC staff member indicates on your Lab Card that you are OK to take the Unit 5 Exam. Also, keep this sign off page, along with your completed lab worksheets, as proof of your lab completion. If your Lab Card indicates that you have not completed the required Labs for this Unit, and you feel that you have, it is up to you to provide proof that you have indeed done the Labs. Keep this page! ___________ Unit 5, Step 2A (Mitosis demonstration and verbal questions) ___________ Unit 5, Step 2B (Meiosis - check of Telophase II and answers to written questions) ___________ Unit 5, Step 2C (Online Karyotyping activity) *BLC Staff: After the student receives his/her last initial on this page, please record that he/she has completed the required lab signoffs for this unit.Page 2 of 9 NOTE: DO NOT ATTEMPT ANY OF THESE LABS UNTIL AFTER YOU HAVE READ THE TEXTBOOK CHAPTER AND VIEWED THE CORRESPONDING STUDY GUIDE! THEY PROVIDE THE NECESSARY BACKGROUND INFORMATION. Unit 5, STEP 2A: Mitosis lab activity This lab must be done in the Biology Learning Center. Additional illustrations (within a PowerPoint presentation) are located in Unit 5, Step 2A&B, of the BIO 100 Course Website. To begin, go to Biology 100 Course Website, click on the Unit 5 link on the Course Content page, scroll down to find Step 2, and then click on the link to the “Mitosis and Meiosis lab illustrations”. Follow the instructions on these worksheets, along with the illustrations in the PowerPoint presentation. At the end, you will demonstrate the different phases of mitosis in front of a BLC staff member, while also answering some questions. You will need the following materials: KIT #101 3 blank sheets of 8 ½” x 11” white paper (you can use scratch paper as long as it is blank on one side). You will use one of these blank sheets of paper for Step 2B, Meiosis. Note that the human body has 46 total chromosomes in each somatic (non-sex) cell. However, it would be impractical to do this exercise with 46 chromosomes. Instead, we are only using 4 total chromosomes, or two homologous pairs of chromosomes (1 small pair of red and white chromosomes and l large pair of red and white chromosomes). Your PowerPoint presentation includes 13 different slides. We will begin with slide #1. ______________________________________________________________________________ Slide #1 MITOSIS: PROPHASE To begin, on a blank sheet of paper (serving as your “cell”) draw the 2 centrioles (shown as 2 large, black circles in the PowerPoint slide) on either side of the paper. Be sure that your paper is positioned in the same orientation as in the PowerPoint. Add the microtubules (shown as dotted lines in the PowerPoint slide). Your microtubules should connect to each of the centrioles in the same way as in the Powerpoint illustration. Next, take your chromosomes out of the kit envelope. Be sure that they are assembled just like in the PowerPoint illustration. You should have 4 total chromosomes: 1 small, white “X” with a large, black bead holding the X together, 1 small, red “X” with a large, black bead holding the X together, 1 large, white “X” with a large black bead holding the X together, and 1 large, red “X” with a large, black bead holding the X together. Note that the large, black bead is the centromere, and the two parts of each “X” (each chromosome) stand for sister chromatids. Thus, each of the 4 chromosomes has a centromere and two sister chromatids.(3rd ed.) Page 3 Each of the large chromosomes also has smaller colored beads, which we will use when we demonstrate meiosis (Step B). These smaller beads stand for alleles (alternate forms of a gene). The large, red chromosome should have a green bead and a blue bead on each sister chromatid (with the blue beads positioned closest to the centromere), whereas the large white, chromosome should have a yellow bead and a pink bead on each sister chromatid (with the pink beads positioned closest to the centromere). Be sure that they are oriented on the chromosomes just like in the PowerPoint illustration. Place your 4 chromosomes on your paper containing the centrioles and microtubules. Note that in prophase the chromosomes are randomly distributed within the cell. Thus, place them randomly on your paper. They do not have to be in the same orientation as in the Powerpoint slide. There is one more thing that we should mention about prophase. During prophase, the nuclear envelope breaks down. However, you are not going to show that event in your “cell” (on your paper). To review, 3 major events occur during prophase: 1. DNA condenses into chromosomes -- you placed your 4 (condensed) chromosomes randomly within your “cell” (the sheet of paper). 2. Microtubules form and radiate from centrioles at opposite poles of the cell -- you drew your centrioles and microtubules within your “cell” (on your blank sheet of paper). 3. The nuclear envelope breaks down -- you are not demonstrating this event. ______________________________________________________________________________ Slide #2 MITOSIS: METAPHASE Now position your chromosomes as shown in slide 2. Note that your paper is smaller than the one used in the PowerPoint slide. Thus, you will not be able to position your chromosomes in exactly the same way as the illustration. Just make sure that two of your centromeres touch the microtubules (dotted lines on your paper) and that all of your chromosomes are lined up down the middle of the paper. The edges of two of your chromosomes will likely have to go off the paper in order to orient in this way. In metaphase: 1. The chromosomes line up in the middle, or equator, of the cell (between the two poles). 2. Microtubules attach to each of the chromosomes at their centromeres. ______________________________________________________________________________Page 4 of 9