Stroma:
- The stroma is the fluid-filled space that surrounds the thylakoid stacks (grana) in the chloroplasts.
- It contains enzymes and other molecules required for the synthesis of sugars during the light-independent reactions of photosynthesis.
- The stroma is not the stack of vesicles itself.
Granum:
- Granum refers to the stack of vesicles found inside plastids, specifically within the chloroplasts of plant cells.
- These granum stacks comprise flattened membranous sacs called thylakoids.
- The thylakoids contain the chlorophyll pigments responsible for light absorption and the conversion of light energy into chemical energy during the process of photosynthesis.
Oxysome:
- Oxysome is not a term typically used to describe the stack of vesicles found inside plastids. It does not specifically refer to this particular structure or function within the plastids.
Thylakoid:
- Thylakoid refers to the individual membranous sacs that make up the stack of vesicles found inside plastids, specifically the granum within chloroplasts.
- Thylakoids are responsible for housing the photosynthetic pigments, such as chlorophyll, which capture light energy and participate in the light-dependent reactions of photosynthesis.
What is chloroplast made of?
Chloroplasts are complex organelles found in plant cells and some algae. They are primarily responsible for carrying out photosynthesis, the process by which light energy is converted into chemical energy (in the form of glucose) using carbon dioxide and water.
Chloroplasts are double-membraned organelles with their own set of DNA, RNA, and protein-synthesizing machinery. Some components that make up chloroplasts include:
1. Inner and Outer Membranes:
Chloroplasts have a double membrane system that separates the interior of the organelle from the surrounding cytoplasm of the cell. The inner membrane encloses the stroma, while the outer membrane acts as a barrier between the chloroplast and the rest of the cell.
2. Stroma:
The stroma is the semi-fluid matrix that fills the chloroplast interior, enclosed by the inner membrane. It contains various enzymes required for the Calvin cycle, also known as the light-independent reactions of photosynthesis.
3. Thylakoid Membranes:
Within the chloroplast, the stroma is organized into stacks of flattened membrane sacs called thylakoids. These thylakoid membranes contain the chlorophyll pigments and other associated proteins that capture light energy during the light-dependent reactions of photosynthesis.
4. Grana:
The grana are stacks of thylakoid membranes. These stacks increase the surface area available for light absorption and provide an organized arrangement of the photosynthetic machinery, optimizing the efficiency of photosynthesis.
5. Chlorophyll and Other Pigments:
Chloroplasts contain various types of pigments, including chlorophyll a, chlorophyll b, carotenoids, and xanthophylls. These pigments absorb different wavelengths of light, enabling the chloroplasts to capture a broader range of light energy for photosynthesis.
6. DNA and Ribosomes:
Chloroplasts have their own circular DNA and can synthesize some of their own proteins using ribosomes. This DNA encodes for essential proteins involved in chloroplast function and development.
