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Key Ideas

  • Mitosis is the division of replicated chromosomes which is necessary for making new cells having the same number of chromosomes and the same traits as the parent cells.
  • Meiosis is the division process that reduces the chromosome number, producing gametes (sperm and ova) in preparation for fertilization.
  • Fertilization, or union of sperm and ovum, yields a zygote (fertilized ovum) and restores the normal number of chromosomes in somatic cells of that new organism.
  • Models are important tools that help geneticists explain biological processes.

Overview

Applying and extending their knowledge of chromosomes and heredity, students learn about the differences between mitosis and meiosis. They identify mitosis as a process necessary for cell division of somatic cells to produce exact copies of parent cells for growth, replacement, and repair. Through a simulation, students demonstrate and explain that meiosis is a unique type of cell division to produce gametes (sperm and ova) that have half the number of chromosomes, in preparation for fertilization. At fertilization, the union of sperm and egg restores the normal number of chromosomes for that organism, ensuring continuity of genetic information from one generation to another.

Objectives

Students:

\checkmark distinguish the differences between mitosis and meiosis.

\checkmark demonstrate and explain the process of meiosis.

\checkmark simulate and explain the transfer of chromosomes during fertilization.

\checkmark explain the importance of DNA replication and meiosis to the continuity of a species.

\checkmark propose reasons why models are important tools to help geneticists learn more about important processes like DNA replication, mitosis, and fertilization.

Vocabulary

fertilization, gamete cells, meiosis, mitosis, ova, ovum, sperm, zygote

Student Materials

Activity 4-1: Cell Division - Double or Nothing

  • Activity Report
  • Crayons or colored pens or pencils (same colors as pipe cleaners if possible); 2 large paper plates; 8 pipe cleaners (2 long of color A, 2 long of color B, 2 short of color A, and 2 short of color B)

Activity 4-2: Meiosis and Fertilization

  • Data Sheets 1 and 2
  • Activity Report
  • Crayons or colored pens or pencils (same colors as pipe cleaners if possible)
  • 4 large paper plates
  • Pipe cleaner set (4 double pairs) 2 long pairs (Each member of the pairs is made up of 2 long pipe cleaners for a total of 4 pipe cleaners per pair. 1 pair, color A. 1 pair, color B.) 2 short pairs (Each member of the pairs is made up of 2 pipe cleaners for a total of 4 pipe cleaners per pair. 1 pair, color A. 1 pair, color B.)

Teacher Materials

Activity 4-1: Cell Division - Double or Nothing

  • Activity Report Answer Key
  • Additional student supplies

Activity 4-2: Meiosis and Fertilization

  • Activity Report Answer Key
  • Extra pipe cleaners

Advance Preparation

See Activities 4-1 and 4-2 in the student edition.

Activity 4-1: Cell Division - Double or Nothing

  • Collect student materials.
  • You may want to extend students' experiences with Activity 4-1 by using Enrichment 4-1: Chromosome Cards.

Activity 4-2: Meiosis and Fertilization

  • Arrange for video equipment if you plan to tape the activity.
  • Obtain pipe cleaner sets for each team.
  • You may want to extend students' experiences with Activity 4-2 by using Enrichment 4-2: Crossing Over in Meiosis.

Interdisciplinary Connection

Art Compare and contrast mitosis and meiosis by using models, drawings, etc.

Enrichment Activities

Enrichment 4-1: Chromosome Cards

This Enrichment activity extends students' experiences with Activity 4-1. Because this is an extension of Activity 4-1, there are no Teacher Activity Notes or Activity Report, There is a Student Activity Guide on TE page 58. Students should complete Activity 4-1 before they complete Enrichment 4-1.

If you choose to do this optional activity, consider the following:

  1. Laminate the chromosome cards before students use them.
  2. Encourage students to enhance their demonstrations of chromosome card movements with verbal and/or written explanations.
  3. Students can summarize what they learned by completing one of the following additional creative activities to share with classmates.

They can create a

  • poster.
  • book, with illustrations.
  • poem.
  • computer simulation.

Enrichment 4-2: Crossing Over in Meiosis

This Enrichment activity extends students' experiences with Activity 4-2. Because this is an extension of Activity 4-2, there are no Teacher Activity Notes. There is a Student Activity Guide on TE page 63. The Teacher Resource for Enrichment 4-2 provides background information on meiosis. Students should complete Activity 4-2 before they complete Enrichment 4-2.

This activity illustrates genetic variation in gametes.

Encourage students to investigate nondisjunction of chromosomes and the results in humans. For example, Down syndrome results from nondisjunction of chromosome pair 21.

Image Attributions

Description

Authors:

Grades:

6 , 7 , 8

Date Created:

Feb 23, 2012

Last Modified:

Feb 23, 2012
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CK.SCI.ENG.TE.1.Human-Biology-Genetics.5.1

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