Cell Junctions Explorer
About This MicroSim
This interactive diagram compares the four major types of cell junctions found in animal and plant tissues. The image is organized as a 2x2 grid showing tight junctions, desmosomes, gap junctions, and plasmodesmata in cross-section between adjacent cells.
Use Explore mode to hover over each structure and learn about its molecular components and biological function. Switch to Quiz mode to test your ability to identify junction components.
How to Use
- Explore mode — Hover over any numbered marker or label to see a description and AP exam tip
- Quiz mode — A structure name appears in the prompt; click the correct marker on the diagram
- Compare junction types by exploring structures across all four quadrants
Junction Types at a Glance
| Junction Type | Key Proteins | Function | Found In |
|---|---|---|---|
| Tight Junction | Claudins, occludins | Seals intercellular space; prevents leakage | Epithelial tissues (gut, kidney, bladder) |
| Desmosome | Cadherins (desmoglein), keratin | Mechanical anchoring; resists stretching | Skin, heart muscle, uterus |
| Gap Junction | Connexins (6 per connexon) | Direct cytoplasmic communication; passes ions and second messengers | Heart muscle, smooth muscle, neurons |
| Plasmodesma | Plasma membrane + desmotubule (ER) | Plant cell-to-cell channel; symplastic transport | All plant tissues |
Lesson Plan
Grade Level
9-12 (AP Biology)
Duration
10-15 minutes
Prerequisites
- Plasma membrane structure
- Cytoskeleton components (intermediate filaments)
- Cell signaling basics (second messengers)
Activities
- Exploration (5 min): Use Explore mode to examine all four junction types, focusing on structural proteins and their functions
- Guided Practice (5 min): Compare tight junctions (sealing) vs. gap junctions (communication) — how do their structures reflect their opposite functions?
- Assessment (5 min): Complete Quiz mode; then answer: How are gap junctions and plasmodesmata analogous? How do they differ structurally?
Assessment
- Can students explain why tight junctions force transcellular (not paracellular) transport?
- Can students distinguish the mechanical role of desmosomes from the sealing role of tight junctions?
- Can students compare gap junctions (animal) to plasmodesmata (plant) as analogous structures?