Lesson Plan 2

Basics of Transcription and Translation

8th grade Science

Overview

The lesson will provide students a connection between material they have learned about DNA structure and how it ties into macromolecules and genetic inheritance. Using just 8 bullet point notes, the lesson will cover the process of sending a coded message from the nucleus to the cytosol to the ribosome for making a protein.

Estimated Time

55 minutes

Essential Questions

How is genetic information moved from the nucleus to proteins?

What is the evolutionary rationale for messenger RNA and tRNA?

Knowledge Objectives

Students should know: what mRNA is, how it is related to DNA, the exact amount of DNA used in each mRNA, how long unbundled DNA is, where the mRNA arrives at in the cytosol, the function of the ribosomes, and what tRNA is.

Materials

Laptop, projectors, PowerPoint, student lab notebooks.

“The Central Dogma of Biology” video from the DNA Learning Center (Cold Spring Harbor) on YouTube: https://www.youtube.com/watch?v=9kOGOY7vthk

Vocabulary

Transcription: “Copying down the DNA code to a message”

Translation: “Telling the message to the ribosome to make a protein”

Amino Acid: “Building block of proteins”

Prerequisite knowledge/skills

Students will have learned about the molecule structure of DNA and base-pairing rules and what “sequence” means. Students will also understand that DNA is inherited and is responsible for generating traits that are observable on the outside.

Lesson

1.) Do Now: Copy vocabulary and definitions

2.) Add notes title and page number to notebook table of contents

3.) Set up the notes page with the title and one horizontal line for each slide

4.) Conceptual introduction: DNA codes for the instructions for life, but DNA is trapped inside the nucleus. How does the cell get instructions from the DNA? Some probing questions to explain why DNA is trapped in the nucleus could be: “How long is one molecule of DNA? If we lined up each strand of DNA from each cell in our body, it would go to the sun and back.”

5.) Transcription (Top of notes page)

“DNA code is copied to a messenger”

“Messenger leaves nucleus and goes to ribosome”

“The messenger tells the code to the ribosome”

“What is this messenger called? mRNA”

Can use hypothetical stories to relate to everyday experiences for the children.

6.) Pop Quiz (To wake students up)

“What are the 4 macromolecules of life? (Lipids, Carbohydrates, Nucleic Acids, and Proteins”

“Where are proteins made? (Ribosomes)”

Emphasize that proteins are the most important of those 4 molecules

7.) Translation (Bottom of notes page)

“Ribosomes can’t read the message”

“Ribosomes have to translate the message into amino acids”

“This allows your body to make proteins (Skin, Hair, Muscles)”

Ask students if “Messenger RNA is called mRNA, what is Transfer RNA called? (tRNA)”

Engagement Activity

Students at each table are broken into 4 numbers, and each number is given a different secret code in secret (simulating the opening of DNA to begin transcription).

Students start by copying the message down. Then, the paper is passed in a circle and students begin to encode the message (simple Caesar cipher) (simulates transcription). The original message is taken and students pass the encoded message. The code is deciphered and then passed (simulating translation). The deciphered code is then compared to the original message for mistakes.

Optional quantification activity: students can count the number of mistakes (normalized as a percent of message length) and see whose table completed the tasks with the fewest mistakes.