Thylakoidlevyt

Thylakoidlevyt are the internal membrane structures found within chloroplasts of plant cells and algae. The term is a combination of the scientific word “thylakoid” and the Finnish noun “levyt,” meaning plates or membranes, and is used in Finnish literature to refer to the stack of thylakoid membranes that make up the photosynthetic machinery of photosynthetic organisms.

These membranes are composed primarily of amphiphilic phospholipids and proteins, including the pigment–protein complexes of photosystem I and photosystem II. They form a highly ordered 3‑dimensional system in which light‑absorbing chlorophyll and accessory pigments are embedded in specialised sites such as the light‑harvesting complexes.

The thylakoid lumen is the interior region of each membrane invagination. Through a series of electron transport reactions driven by light energy, the thylakoid system establishes a proton gradient across the membrane. This proton motive force powers ATP synthase, leading to the synthesis of ATP, while reducing power in the form of NADPH is produced. The ATP and NADPH generated are then used in the Calvin‑Benson cycle for carbon fixation.

Thylakoidmembranes also participate in the regulation of photoprotective mechanisms such as non‑photochemical quenching, which dissipates excess excitation energy as heat. Their structure and composition are subject to dynamic remodeling in response to environmental conditions, including light quality, intensity, and nutrient availability.

In addition to plant chloroplasts, thylakoidmembranes are present in the chloroplasts of various algae (e.g., green algae and diatoms) and even in cyanobacteria, where they are often referred to as thylakoid thylakoids. In cyanobacteria they form diffuse thylakoid networks, whereas in eukaryotic chloroplasts the membranes are organized into compact stacks called grana.

Research on thylakoidlevyt has led to advances in artificial photosynthesis, bioenergy production, and the design of light‑harvesting biomimetic devices, underscoring their importance not only for basic plant biology but also for applied science.