Lesson 5. Closer Look at Meiosis

Estimated Time: 1 period

Objective

To identify why sexually reproducing organisms need meiosis for reproduction

EQ: Why is mitosis not good enough for sexually reproducing organisms?

Bridge

Why does the process of meiosis have to be different from the process of mitosis?

Mini Lesson

Share out responses from the bridge

Meiosis is the process of making sex cells (sperm cells in males (pollen in male plants) and egg cells in females) that we call gametes. These gametes are responsible for carrying the genetic information that may or may not become the offspring for the organism. Every other cell in our body will undergo mitosis, not meiosis. Why is that?

Let’s take a look at these processes side by side. As we watch the video, list what they have in common and what’s different and use this list to answer that question.

Take a look again at how recombination works in meiosis:

Let’s learn the meiosis song: sung to the tune of Frere Jacques (are you sleeping) have students repeat after you for the second set

Meiosis, Meiosis

Makes gametes, makes gametes

4 at a time, 4 at a time

Half the genes, half the genes

Work Period

Take the “imaginary organism” from your protein synthesis activity where you had to draw the organism from the protein code. Pair up with another group and assign one to be the boy (indicate the boy by placing XY on the paper) and one to be the girl (indicate the girl by placing XX on the paper). Show the process of meiosis in each of the organisms, drawing out the chromosomes at each stage (you can copy the colors you don’t need to copy the letters at this point). You need to show crossing over in at least 2 of your chromosomes. Do this on a separate sheet of paper.

What would have happened to the offspring of your organism if they had not gone through that second division?

Summary

Answer the EQ

Closing

Before we asked why it could be so detrimental to have a mutation during DNA replication as opposed to during transcription or translation. We will answer that don’t forget it! But during which of the processes, mitosis or meiosis, would a mutation have an effect on the offspring? How do you know?

SPED and ELL Modifications:

Additional Hands On piece before the Bridge:

  1. Give students a list of sentence strips for the bridge- have them sort in two groups: mitosis and meiosis

(Be sure that they group exact copy of cells with mitosis and genetically varied cells with the process of meiosis.)

  1. Then give students images of cells made by mitosis and meiosis (ex: of clones, and siblings- ( a visual demonstration/activity- to help draw same conclusion as listed in the bridge)

Apps and Internet Activities:

  1. SONGIFY app: Use the Songify App to make the Meiosis song in the mini lesson. Students could also use the voice memo recording tool on the iPads to make a song recording used in the mini lesson as well.
  1. An imaginary activity that demonstrates crossing over in a very visual and hands on way:
  1. A virtual Meiosis Lab
  1. A cloning activity:

Independent Practice

Reading on Genetic disorders: Trisomy 5 vs 18 vs 21 with questions (one or two they will have these for the next couple of days since we will only spend one day in class on this and it will give them a background to work from for those that bother to do homework)