Labs & Activities › Cell differentiation activity

Same DNA, Different Cells

A neuron and a red blood cell are very different, yet they carry the same DNA. Use cell cards to see how cells become specialized.

30–40 minutes
Pairs or groups of 3–4
Paper only
Biology BIO.1E.1
Foundations FB.3.1

Question

If every body cell has the same DNA, why do different cells look and work differently?

Background

An embryo starts as one cell. That cell divides again and again. As the cells divide, they differentiate, which means they become specialized for a job. All the cells in your body that came from the same fertilized egg have the same DNA. What differs is which genes are turned on. A muscle cell uses the genes for muscle proteins. A red blood cell uses the genes for hemoglobin. The genes that are not needed stay off. Stem cells have not specialized yet and can become many kinds of cells. Differentiated cells also divide to repair and replace tissue, and they pass on the same DNA to their daughter cells.

differentiation
specialized cell
stem cell
gene expression
tissue
mitosis

Activity

Read the cell cards below. Each one gives the cell’s job and a key structure.
Complete the table: for each cell, write how its structure helps it do its job.
In the last column, write the main protein or product the cell makes a lot of. Use the clue in the card.
Answer the analysis questions.

Cell card 1

Neuron (nerve cell)

Job: carry electrical signals over long distances.

Structure: long extension called an axon with branches.

Clue: makes ion channels and signaling molecules.

Cell card 2

Red blood cell

Job: carry oxygen.

Structure: flat disc, no nucleus when mature.

Clue: packed with hemoglobin.

Cell card 3

Skeletal muscle cell

Job: contract to move bones.

Structure: long fibers with many mitochondria.

Clue: makes actin and myosin.

Cell card 4

Root hair cell (plant)

Job: absorb water and minerals from soil.

Structure: a long thin projection that increases surface area.

Clue: has many transport proteins in the membrane.

Cell card 5

Pancreatic cell

Job: make and release hormones and digestive enzymes.

Structure: lots of rough endoplasmic reticulum and Golgi.

Clue: makes insulin or digestive enzymes.

Cell card 6

Guard cell (plant)

Job: open and close a leaf pore called a stomate.

Structure: a pair of bean-shaped cells with chloroplasts.

Clue: changes shape when water moves in or out.

Specialized cells
Cell	How the structure fits the job	Main protein or product
Neuron
Red blood cell
Skeletal muscle cell
Root hair cell
Pancreatic cell
Guard cell

Analysis

The neuron and the muscle cell in the same person have the same DNA. What is different about them?
Explain why a fertilized egg and a muscle cell can have identical DNA but only the muscle cell makes large amounts of myosin.
Using the words mitosis and differentiation, explain how one fertilized egg becomes a body with many cell types.
What is a stem cell, and why are stem cells useful for repairing tissue?
When a skin cell divides to heal a cut, what DNA do the daughter cells have? Explain.

Teacher notes

Preparation and tips

Print the cards or let students use the screen. For a movement version, cut the cards apart and have groups sort them by the organ system or kingdom, then add the job.
Foundations: you can skip the pancreatic and guard cell cards and keep the focus on structure fits function.

What to expect

Neuron: long axon reaches other cells; product: ion channels. Red blood cell: flat disc with no nucleus gives more room for hemoglobin. Muscle: long fibers and mitochondria for energy; actin and myosin. Root hair: surface area for absorption; transport proteins. Pancreatic: rough ER and Golgi to make and package proteins; insulin or enzymes. Guard cell: bean shape and flexible walls control the pore; changes shape with water.
Key idea: same DNA, different genes expressed. Daughter cells from mitosis have the same DNA as the parent cell.

Alignment

Biology BIO.1E.1 (cell division and cell differentiation produce and maintain complex multicellular organisms). Enrichment connection: BIO.1E.4 (stem cells). Foundations follows regular Biology.