Simplified AI-generated chloroplast illustration with labels added separately. Membrane spacing and stack sizes are schematic.
A chloroplast organizes photosynthesis into connected compartments. Its envelope encloses the stroma, while an internal thylakoid membrane system provides surfaces for the light-dependent reactions.
The cutaway is useful because it separates three ideas that are often confused: a thylakoid is an individual membrane compartment, a granum is a stack of thylakoids, and the stroma is the fluid region around them.
Parts and functions
| Structure | What it does |
|---|---|
| Outer membrane | The outer boundary of the chloroplast envelope. |
| Inner membrane | The inner boundary of the envelope, enclosing the stroma. |
| Stroma | The fluid compartment containing enzymes involved in the Calvin cycle. |
| Thylakoid | A membrane-bound internal compartment; its membrane hosts the light-dependent reactions. |
| Granum (plural: grana) | A stack of thylakoids. |
| Stroma lamella | A membrane connection between regions of the thylakoid system. |
Connect structure with the two major stages
The light-dependent reactions take place in the thylakoid membrane. The Calvin cycle takes place in the stroma and uses products of those light reactions to support carbon fixation.
A labeled anatomy diagram and a process diagram answer different questions. Use this cutaway to explain where the stages happen. Use a separate photosynthesis overview to explain what enters, what leaves and how energy is transferred.
Thylakoid, granum and stroma: three different labels
Point to one flattened membrane compartment when introducing a thylakoid. Point to a stack when introducing a granum. Point to the fluid space outside the stacks when introducing the stroma.
The inside of a thylakoid is its lumen. The stroma and lumen are separated by the thylakoid membrane; they are not two names for the same region. This simplified figure does not enlarge the lumen as a separate labeled inset.
Use the cutaway in a teaching sequence
Start with the whole plant cell, enlarge one chloroplast, then switch to a process schematic. This sequence gives students a sense of scale without implying that the illustration itself has measured dimensions.
In Figure Maker, keep the envelope and stacks stable while adjusting label density. For a short revision slide, the three labels stroma, thylakoid and granum may be enough.
A prompt to start from
Frequently asked questions
References and further reading
Illustrations are explanatory models. Colors, proportions and selected structures are simplified to support the topic.
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Open a starter, adapt the labels, and create an illustration for your next lecture or research discussion.
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