Which statement about thylakoids in eukaryotes is not correct?
Thylakoids are assembled into stacks.
Thylakoids exist as a maze of folded membranes.
The space surrounding thylakoids is called stroma.
Thylakoids contain chlorophyll.
The Correct Answer and Explanation is :
The incorrect statement is: “Thylakoids exist as a maze of folded membranes.”
Correct Answer:
In eukaryotic cells, specifically in plants and algae, thylakoids are not structured as a maze of folded membranes. Instead, they are organized into stacks called grana. The grana are interconnected by unstacked thylakoid membranes known as lamellae or stromal thylakoids, creating a continuous membrane system within the chloroplast.
Thylakoid Structure and Function:
Thylakoids are flattened, membrane-bound sacs found within the chloroplasts. They are key components of the photosynthetic machinery and play a crucial role in the light-dependent reactions of photosynthesis. Each thylakoid membrane contains proteins, pigments (such as chlorophyll), and enzymes that capture light energy and convert it into chemical energy in the form of ATP and NADPH.
Stacks (Grana): Thylakoids are often stacked in columns, forming structures called grana. These stacks increase the surface area for light absorption, which is critical for efficient photosynthesis. The grana are interconnected by single, unstacked thylakoids that extend through the stroma, forming a unified network.
Chlorophyll: The thylakoid membrane is embedded with pigments, including chlorophyll, which absorbs light primarily in the blue and red parts of the spectrum. This light energy is used to drive the splitting of water molecules, generating oxygen and electrons that help form ATP and NADPH.
Stroma: The space surrounding the thylakoid membrane is the stroma, a fluid-filled matrix that contains enzymes necessary for the Calvin cycle, where the energy captured in the thylakoids is used to fix carbon into sugars.
In summary, thylakoids are not folded into a maze, but are neatly organized into stacks that optimize the chloroplast’s ability to capture and utilize light energy.