Science - Lesson #4: Protein Synthesis Modeling Activity

Body Systems Exam Thursday, 2/5 - Lessons 1-7

Science

Lesson #4:

Protein Synthesis

Learning Intention:

Students will conduct a modeling activity that represents how DNA uses mRNA to make specific shaped proteins.

Success Criteria:

I am successful when I can...

1) Loop back to past units in preparation for the regents.

2) Complete a hands-on model that demonstrates translation and transcription.

3) Communicate instructions to my peers.

Agenda:

Part 1: Regents Application

Part 2: Modeling Activity

Part 3: Stop n' Jot

Reminders:

Tutoring Wednesdays in A-301 after school.

Part 1: Regents Application

(10 min)

The Silent Cell Killer

Ricin is a potent toxin found naturally in the seeds of the castor oil plant (Ricinus communis). It is one of the deadliest substances known; a dose the size of a few grains of salt can be fatal to an adult human.

The danger of ricin lies in its ability to target a specific component of the cell. Once ricin enters a human cell, it acts as an enzyme to structurally modify and permanently disable the ribosomes. A single molecule of ricin can inactivate over 1,500 ribosomes per minute. Without functioning ribosomes, the cell quickly loses its ability to maintain its structure or catalyze chemical reactions, leading to rapid cell death and organ failure.

1. If a scientist were to analyze the cytoplasm of a cell shortly after exposure to ricin, they would likely observe an abnormal accumulation of which specific building blocks?

(1) Simple sugars, because mitochondria are disabled.

(2) Amino acids, because they are not being assembled into chains.

(3) Fatty acids, because the cell membrane is dissolving.

(4) Nucleotides, because DNA replication has accelerated.

2. The symptoms of ricin poisoning occur because the disabled ribosomes prevent the cell from expressing its genetic code. This directly stops the synthesis of which class of organic molecules?

(1) Carbohydrates, such as glucose.

(2) Lipids, such as steroid hormones.

(3) Nucleic acids, such as DNA.

(4) Proteins, such as enzymes.

3. (Short Response) Identify one specific protein molecule required by the human body. Explain the specific negative effect on the body if ricin prevented the synthesis of this protein.

Part 2:

Modeling Activity

(15 min)

Today, you will model how DNA sends a message to the ribosome, telling it what amino acids to string together in order to make a specific shaped protein.

Remember, protein shape determines the function (job) of the protein.

Step by Step Directions

1) One person from each group will step outside with Mr. Pinho. These students represent DNA. They know how to make the protein but are trapped in the hallway (Nucleus).

2) One person from each group will act as messenger RNA. They will listen to the DNAs instructions and then recite them to the ribosomes.

3) One or two people at the table will be the ribosomes. They will build the protein using the amino acid blocks provided.

4) First group to build their protein correctly wins!

Modeling Key

DNA - The person in the hallway reading the instructions.

RNA - The person carrying the instructions

Ribosome - The two people building the protein using different amino acids.

Mutation: An error in the instructions that may change the shape of the protein.

Amino Acid: The plastic connectors we will be using.

Part 3:

Stop n' Jot

(2 min)

We just modeled how DNA sends mRNA instructions to the ribosome so that it can string together amino acids in a specific sequence and make a specific shaped protein. These events have specific names:

Transcription: DNA makes mRNA to carry instructions for making protein.

Translation: The mRNA instructions are read by the ribosome and it strings together amino acids in a sequence (order) to make a protein.

Part 4: Protein Shape Determines Traits

(10 min)

Some people have genes that code for a specific trait, while others do not. We are going to make a class gene tree to see what traits our genes code for.

We will focus on three traits:

1) Ability to taste PCT

2) Attached Ear Lobes

3) Ability to roll tongue

Part 5: Exit Ticket

Answer the short response questions on the Google form below:

1) What is the most common combination of traits in the class?

2) What is the least common combination of traits in the class?

3) Is the number of people in this experiment enough to determine the percentage of these traits in the human population? Why/Why not?

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