Cell Structure: Biology - Grade 9

Subject: Biology

Grade: 9

Lesson Objective: Understanding the structure and the function of a cell.

Common Core Standard: CCSS.ELA-LITERACY.RST.9-10.4 - Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9-10 texts and topics.

Materials

• Sheet of plastic or other table covering
• Glass Bowl
• Jello
• Unsharpened pencil
• Pipe Cleaners
• Tissue paper
• Small Sandwich baggie
• Pom-poms
• Glitter
• Plastic Wrap
• Green construction paper cut into rounds
• Paper Clips

You can use any additional or substitute craft supplies on hand.

Starter

Do:

• Line the bowl with plastic wrap. Follow the Jell-o directions; pour into the bowl. Cool overnight.

Say:

• All living creatures are made up of cells.
• Today we are going to look at what those structures are and how they function, all while building our own three-dimensional model of a cell!

Main

Say/Do:

• Stand in front of the class with students close—place the bowl of Jell-o on the covered table's center.

Say:

• Representing our cell we have a bowl of Jell-O. Plant cells have a unique feature called a cell wall. Animal cells do not have this wall. Today, we will be making a plant cell. Which part of our cell represents the cell wall?
• Allow students to answer. The bowl will function as your cell wall, while the plastic wrap will serve as the membrane. The Jell-o will be the cytoplasm.

Say:

• We are using the bowl as our cell wall. This gives the cell a rigid structure. Inside our bowl, we have a secondary boundary, the plastic wrap. This will function as the cell membrane.
• Cell membranes differ from cell walls because cell walls are fully permeable. This means outside materials may pass through this wall. The cell membrane is selectively permeable, having the ability to sort through what it allows to pass through to the cytoplasm. The Jell-O represents cytoplasm.
• Cytoplasm carries enzymes, molecules, and pathways for the cell. It is particularly important for the structure and function of the cell. The next organelle in our cell is going to be the nucleus.
• The nucleus functions as the brain of the cell. This is where genetic material is stored and processed. The nucleus is the most easily recognizable structure in the cell. It is round and surrounded by membranes. In addition to housing the chromosomes, the nucleus can also make copies of the DNA that is stored within the chromosomes. This is what gives direction to the cell during all stages of its life.
• Allow a student to push a pom-pom into the Jell-o as the nucleus.

Say:

• Does anyone know what the vacuole does?
• Allow students to discuss what the primary function of the vacuole may be. Bring a student forward to place the baggie into the Jell-o. This will represent the vacuole.

Say:

• The vacuole is a structure within the cytoplasm that does not have a set shape or structure. It is large in plant cells, taking up most of the interior of the cell. Vacuoles perform several duties, much of which is storage. While it stores the nutrients of the cell, it also has space to hold the cell waste. Now we will focus on Ribosomes. Ribosomes are found in the cytoplasm. They are small particles that are made of RNA and proteins. They bind the two types of RNA together. 
• Sprinkle the glitter lightly throughout the Jell-o portion of the cell to represent ribosomes.

Say:

• Ribosomes are also found near the nucleus on the rough endoplasmic reticulum. The endoplasmic reticulum borders the nucleus. A cell has two types of endoplasmic reticulum: smooth and rough. They both act as the highway of the cell. First the endoplasmic reticulum processes protein, and then it transports it from its location near the nucleus to our next part of the cell.
• Ask a student to come forward and pick out two pipe cleaners, bending them into zig-zag shapes. They may sprinkle glitter lightly onto one before pressing them into the Jell-o as close to the nucleus as they can.

Say:

• Once the endoplasmic reticulum are done transporting the proteins, they bring them to the Golgi body.
• The Golgi body's most important function is to package the proteins brought to it by the endoplasmic reticulum. Once it packages the proteins, they continue following various pathways to their destinations.
• This process happens in the folds of the membranes that make up the Golgi body's folded structure.
• Allow for another student to come forward. Let them fold a small piece of tissue paper into a stack and place it near the endoplasmic reticulum.

Say:

• Next, we have the amyloplast. Amyloplasts are small organelles in our cells that process starches.   
• Have a student select a small pom and place it in the Jell-o.

Say:

• Chloroplasts are where photosynthesis takes place. Photosynthesis is when plants turn sunlight into energy. This process does not exist in animal cells. Photosynthesis can occur because of chlorophyll—what gives plants their green color—contained in the chloroplast.
• Place a green circle into your Jell-o.

Say:

• Finally, our last organelle is the mitochondria. The mitochondria produce energy by taking carbohydrates and combining them with oxygen in a process known as respiration.
• Mitochondria may be oval or round and have two membranes. The inner membrane is folded many times over, allowing for a larger surface area. This assists the energy-making processes.
• Ask a student forward, have them fold many paper clips together. This can serve as your mitochondria. Allow student to place in Jell-o.

Feedback

Say:

• Now that we have built our own cell together, we should have a much better understanding of how a cell looks and functions.
• Each of us and every living creature is built up entirely of cells, from the smallest single-celled organisms to elephants and whales.
• We have discussed the many basic jobs each of the organelles in our cell perform, are there any further questions?

Written by Amber White

Education World Contributor

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