Meiosis Drawings

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The Cellular Basis of Inheritance

BIO 106 Life Sciences

Brightpoint Community College

OBJECTIVES

After completing this exercise, you will be able to:

· Discuss the importance of sexual reproduction.

· Describe the events that occur during the production of gametes.

· Chart chromosomal movement during meiosis.

· Observe and identify cells at various stages in meiosis.

· Compare and contrast the process of mitosis and meiosis.

SUBMISSION INSTRUCTIONS (Post-Lab Quiz)

After you have completed the lab, you will transfer your answers to a post-lab quiz in Canvas and submit the quiz. You will not turn in the lab protocol. Most students find it’s easier to answer all the questions in the lab and then transfer their answers to the post-lab quiz or lab data sheet.

QUESTIONS IN LAB or POST-LAB . Transfer your answers to Post Lab 7. A link to Lab 7 can be found on Chapter 7 and Lab 7 Overview in Module 2 in Canvas. As you review the post-lab quiz, you will see that many of the lab questions are converted to multiple choice questions to help guide you. Pick the best answer. You must use complete sentences for short answer- or essay questions. If there is a rubric at the end of the question, read and follow the rubric for full credit.

LAB DATA QUESTIONS . Data tables, graphs, etc. should be transferred to lab data sheet 7.

· A link for the lab handout can be found on Chapter 7and Lab 7 in Module 2 in Canvas.

· Once you have filled out the lab data sheet, save it as a PDF file and then upload to the last question on the post lab in Canvas.

INITIAL KNOWLEDGE CHECK

PROCEDURE:

Show your level of knowledge about the following concepts by putting a “x” in the box that best describes your understanding in Table 1. To paraphrase Yoda, “There is no right or wrong, there is only do”

LAB DATA QUESTION 1. Table 1: Assess your understanding of the concepts.

INTRODUCTION

Meiosis is a different type of cell division than mitosis, used to produce eggs and sperm in animals and spores in plants. Unlike most body cells, gametes (eggs and sperm) only have one set of chromosomes. Meiosis reduces the chromosome number by half. It occurs only in the gonads (testes and ovaries) and involves two rounds of cell division, resulting in four haploid gametes. In sexual reproduction, the gametes fuse during fertilization to restore the full chromosome number in the fertilized egg.

In humans, we see how both mitosis and meiosis are used in various stages of the life cycle. Humans have diploid chromosome number (2n) of 46 and a haploid chromosome number (n) of 23. This means that body cells possess 46 chromosomes (2 x 23 =46) and gametes contain 23 chromosomes (1 x 23 =23).

In this lab, you will analyze and draw the movement of chromosomes during mitosis and meiosis. You will also identify plant and animal cells at different stages of cell division. Before starting the lab, review the relevant sections on cell division in your textbook.

I. THE PROCESS OF MEIOSIS

The objective of this activity is to observe and track the movement of a pair of large homologous chromosomes and a pair of small homologous chromosomes during the different phases of meiosis. By accurately representing the chromosomes and their behavior, we can better understand how chromosomes segregate into daughter cells during this specialized form of cell division.

Materials:

Colored pencils, pens, or digital pen.

Textbook or online resources on mitosis

Lab 7 Data sheet.

Procedure:

Print the lab data sheet. Alternatively, use digital drawing software on your computer or tablet and a digital pen if you prefer.

Watch this video to review the different phases of meiosis, such as prophase I, metaphase I, anaphase I, telophase I, and the subsequent phases of meiosis II.

Choose two colors for the chromosomes (e.g., one large, one medium, and one small chromosome colored blue and one large, one medium, and one small chromosome colored red). This color scheme allows you to track the segregation of chromosomes into daughter cells and indicated which chromosomes were inherited from the mother (one color) vs the father (the other color). Video Tutorial: How to show stages of Meiosis.

Start by sketching the chromosomes in Interphase 1, G2 phase. Visualize and draw the large and small homologous chromosomes as they appear after DNA replication, with each chromosome consisting of two sister chromatids attached at the centromere. Use the designated colors to distinguish between the two pairs of homologous chromosomes.

Proceed to prophase I, the longest phase of meiosis. Depict the pairing of homologous chromosomes, known as synapsis, and the formation of structures called tetrads or bivalents. Show the crossing over, where genetic exchange occurs between non-sister chromatids of homologous chromosomes. Maintain the assigned colors to differentiate the two pairs of homologous chromosomes. Label the tetrads and sister chromatids.

Move on to metaphase I, where the tetrads align along the equatorial plane of the cell. Sketch the arrangement and positioning of the chromosomes, showing the separation of the large and small homologous chromosomes and their attachment to the spindle fibers. Use the assigned colors to track the segregation of the homologous chromosomes. Label the metaphase plate.

Progress to anaphase I, where the homologous chromosomes separate and move towards opposite poles of the cell. Depict the separation of the homologous chromosomes and the movement of the individual chromosomes towards their respective poles. Use the assigned colors to track the segregation of the large and small homologous chromosomes. Label the spindle fibers (microtubules).

Continue to telophase I, where the chromosomes arrive at the poles, and cytokinesis follows, resulting in two haploid daughter cells. Sketch the decondensation of the chromosomes and the formation of the nuclear envelope. Ensure that the color-coding for each pair of homologous chromosomes remains consistent.

Repeat the above steps for meiosis II, starting with prophase II and proceeding through metaphase II, anaphase II, and telophase II, until the formation of four haploid daughter cells.

Record your drawings on the lab handout, following the designated sections for each phase of meiosis. Make sure to label the phases, the color-coded homologous chromosomes, and any other important observations or notes.

Review your lab handout to ensure all the required information and sketches are present.

If you have any questions or need further guidance, refer to the corresponding sections on meiosis in your textbook or reliable online resources.

LAB DATA QUESTION 2. Cell DIVISION DRAWINGS – MEIOSIS I.

See Lab Data Sheet

LAB DATA QUESTION 3. CELL DIVISION DRAWINGS – MEIOSIS II

See Lab Data Sheet

Post-Lab Questions

QUESTION 1. Compare and contrast mitosis and meiosis.

QUESTION 2. What are homologous chromosomes?

QUESTION 3. How do homologous chromosomes differ in their behavior between mitosis and meiosis?

QUESTION 4. A cell with 80 chromosomes undergoes meiosis. At the end of meiosis, how many chromosomes are found in daughter cells?

QUESTION 5. A cell with 80 chromosomes undergoes meiosis. At the end of meiosis, how many daughter cells are produced?

QUESTION 6. A cell with 80 chromosomes undergoes meiosis. Are the daughter cells identical to one another or different from one another?

QUESTION 7. Be prepared to match the stages of meiosis with their descriptions.

Post Lab Knowledge Check

Show your level of knowledge about the following concepts by putting a “x” in the box that best describes your understanding in Table 1. To paraphrase Yoda, “There is no right or wrong, there is only do”

LAB DATA QUESTION 1. Table X: Assess your understanding of the concepts.

Post-Lab Assignment Submission Instructions:

Once you have finished this lab activity, you will need to submit your answers using the post-lab assignment on Canvas. Please follow these instructions:

1. You will not turn in this document, the lab protocol.

2. In Canvas, navigate to the corresponding Chapter and Lab module and under Labs, open the post-lab.

3. All the blue Questions have been converted to multiple choice questions on the post lab, pick the best answer.

4. Copy and paste all Lab Handout Questions to the Lab handout, save your completed lab handout as a PDF file on your device.

5. Upload the PDF file of your completed lab answer sheet to the designated area in Canvas for submission.

By following these steps, you will successfully submit your post-lab assignment for assessment.

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