By: Linette Godley

Light dependent reactions

Introduction to Mitosis:
Focus on A brief review of cell division:
stages of mitosis—interphase, prophase, metaphase, anaphase, and telophase.

Meiosis Definition: A type of cell division that reduces chromosome number by half to produce four non-identical haploid gametes (sperm and eggs).

Purpose:
Produce gametes for sexual reproduction.
Ensures genetic diversity and maintains chromosome number across generations.

Genetic Diversity:
Crossing Over: Exchange of genetic material during Prophase I.
Independent Assortment: Random chromosome distribution during Metaphase I.
Fertilization: Combines genetic material from two gametes.

Haploid vs. Diploid:

Diploid (2n): Two sets of chromosomes (body cells).
Haploid (n): One set of chromosomes (gametes).

Scratch Basics: Introduction to the Scratch interface, including how to use sprites, backdrops, and programming blocks to animate biological processes.

Code for Meiosis Animation

1. Initialization
When the green flag is clicked, set up the initial positions and show the nucleus.
when green flag clicked go to x: 0 y: 0
show set size to 50%
create 4 chromosome sprites (you can duplicate the same chromosome sprite)
create nucleus in the center of the screen

2. Prophase I (Chromosomes condense and form pairs)
when green flag clicked, wait 2 seconds, repeat 10, change size by 5, move 10 steps towards the center end

3. Metaphase I (Homologous chromosomes align in pairs)
when I receive [Metaphase I v] go to x: 0 y: 100 // Center of the cell, repeat 2, move 100 steps right, wait 0.5 seconds, move 100 steps left, wait 0.5 seconds, end

4. Anaphase I (Chromosomes are pulled apart)
when I receive [Anaphase I v], repeat 2, move 200 steps right, wait 1 second, move 200 steps left, wait 1 second, end

5. Telophase I (Nucleus reforms and cytokinesis)
when I receive [Telophase I v], create new nucleus sprite at opposite poles, wait 2 seconds, repeat 5, move to opposite side, change size by 5% to simulate the formation of two new nuclei, end

6. Meiosis II (Repeat process like mitosis but with haploid cells)
when I receive [Prophase II v], show spindle fibers, wait 2 seconds

etc

Hook/Minds-On

Start with a short video or animation that visually explains the stages of mitosis. Afterward, ask students what they noticed about the process and how it relates to cell growth and reproduction.
Engage students in a class discussion and ask them to describe the steps of mitosis, and note their responses on the board.

Action

• start by introducing Scratch and explain how it can be used to model biological processes.
• demonstrate how to create a simple Scratch project: use sprites to represent chromosomes.
• add sound or text explanations for each stage to guide the user through the simulation

Activity: students begin working on their Scratch projects-they should animate the process of meiosis in whatever way they want.

• they should check the accuracy of the mitosis stages and add elements to enhance the interactivity and educational value of their projects.

Assessment

How will you gather evidence of student learning?

▢ Observations of:

• observing students while periodically going from group to group during work period

▢ student/teacher conversations (whole class, small group, individual questioning):

• class discussion at the beginning of lesson

▢ student tasks / products that provide students with ways to demonstrate learning, specifically:

• meiosis animation reflection at the end

Consolidation

students share their Scratch projects with the class. As they present, ask them to explain the mitosis stages and the choices they made in representing them in Scratch.

Exit ticket Reflection: Have students reflect on the lesson. What did they learn about mitosis? How did coding help them understand the process better?

They should hand in this short reflection before they leave the class