Meiosis I: Separating Homologous Chromosomes

Biology Grades High School 9:44 Video
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Lesson Description

Explore the stages of Meiosis I: Prophase I, Metaphase I, Anaphase I, and Telophase I. Learn how homologous chromosomes separate, leading to genetic variation.

Video Resource

Phases of meiosis I | Cells | MCAT | Khan Academy

Khan Academy

Duration: 9:44
Watch on YouTube

Key Concepts

  • Homologous chromosomes
  • Chromosomal crossover (recombination)
  • Haploid vs. Diploid
  • Metaphase I: Alignment of homologous pairs
  • Anaphase I: Separation of homologous pairs (not sister chromatids)

Learning Objectives

  • Describe the events of Prophase I, Metaphase I, Anaphase I, and Telophase I.
  • Explain the significance of chromosomal crossover in creating genetic variation.
  • Differentiate between the separation of sister chromatids in mitosis vs. homologous chromosomes in Meiosis I.
  • Define the terms haploid and diploid in the context of meiosis.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing the purpose of meiosis: to produce haploid gametes for sexual reproduction. Briefly recap the differences between mitosis and meiosis, setting the stage for a deeper dive into Meiosis I.
  • Video Viewing and Note-Taking (15 mins)
    Play the Khan Academy video 'Phases of meiosis I'. Instruct students to take detailed notes on each phase: Prophase I, Metaphase I, Anaphase I, and Telophase I, paying close attention to the unique events of each stage.
  • Guided Discussion (10 mins)
    Facilitate a class discussion using the discussion questions below. Encourage students to share their notes and clarify any points of confusion.
  • Interactive Modeling Activity (15 mins)
    Engage students in the 'Chromosome Modeling' activity to physically represent the steps of Meiosis I.
  • Assessment (10 mins)
    Administer the multiple-choice and fill-in-the-blank quizzes to assess student understanding.

Interactive Exercises

  • Chromosome Modeling
    Provide students with pipe cleaners of different colors to represent chromosomes. Have them model the stages of Meiosis I, demonstrating crossover, alignment in metaphase, and separation in anaphase.

Discussion Questions

  • How does chromosomal crossover in Prophase I contribute to genetic diversity?
  • What is the key difference between Anaphase I of meiosis and anaphase of mitosis?
  • Why is it important that homologous chromosomes separate during Meiosis I instead of sister chromatids?

Skills Developed

  • Visualizing complex biological processes
  • Differentiating between similar processes (mitosis vs. meiosis)
  • Critical thinking and problem-solving
  • Note-taking and information synthesis

Multiple Choice Questions

Question 1:

During which phase of meiosis I does chromosomal crossover occur?

Correct Answer: Prophase I

Question 2:

In Metaphase I, what lines up along the metaphase plate?

Correct Answer: Homologous chromosome pairs

Question 3:

What separates during Anaphase I?

Correct Answer: Homologous chromosomes

Question 4:

At the end of Meiosis I, how many cells are produced from one original cell?

Correct Answer: 2

Question 5:

Are the cells at the end of Meiosis I haploid or diploid?

Correct Answer: Haploid

Question 6:

Which structure is responsible for moving chromosomes during meiosis I?

Correct Answer: Microtubules

Question 7:

What is the main event that occurs during Telophase I?

Correct Answer: The nuclear membrane reforms

Question 8:

The exchange of genetic material between homologous chromosomes is called:

Correct Answer: Crossing Over

Question 9:

The random way homologous pairs split is called:

Correct Answer: Random assortment

Question 10:

The number of chromosomes in haploid cells after meiosis I is ____ the number in the original diploid cell.

Correct Answer: Half

Fill in the Blank Questions

Question 1:

The process of cell division that produces gametes is called ________.

Correct Answer: meiosis

Question 2:

Homologous chromosomes pair up during ________ I.

Correct Answer: prophase

Question 3:

The point of attachment between sister chromatids is called the ________.

Correct Answer: centromere

Question 4:

In Anaphase I, ________ chromosomes are separated.

Correct Answer: homologous

Question 5:

The division of the cytoplasm is called ________.

Correct Answer: cytokinesis

Question 6:

A cell with two sets of chromosomes is described as being ________.

Correct Answer: diploid

Question 7:

The microtubules attach to the chromosomes at the ________.

Correct Answer: kinetochores

Question 8:

The structure that forms to divide the cell during cytokinesis is the ________ furrow.

Correct Answer: cleavage

Question 9:

The nuclear envelope reforms during ________ I.

Correct Answer: telophase

Question 10:

Sexual reproduction relies on the production of ________ cells.

Correct Answer: haploid

Educational Standards

B.LS3.1:Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. B.LS3.2:Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors. B.LS1.4:[Standard] Use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms.

Teaching Materials

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