plastid
Học thuậtThân thiện
Definition
Noun: A plastid is a specialized organelle found in the cytoplasm of plant cells and some algae. It is a membrane-bound structure that can contain pigments (like chlorophyll), starch, oils, or proteins, and is involved in processes such as photosynthesis and storage.
Examples of Usage
Advanced Usage
- Development and Interconversion: Plastids can develop from proplastids and can sometimes convert from one type to another (e.g., a chloroplast may turn into a chromoplast during fruit ripening).
- Endosymbiotic Theory: The presence of plastids is a key piece of evidence for the endosymbiotic theory, which proposes that these organelles originated from free-living cyanobacteria that were engulfed by ancestral eukaryotic cells.
Variants and Related Words
- Chloroplast (n): A green plastid containing chlorophyll, where photosynthesis occurs.
- Chromoplast (n): A plastid containing pigments other than chlorophyll, such as carotenoids (red, orange, yellow).
- Leucoplast (n): A colorless plastid involved in the synthesis and storage of food materials like starch (amyloplast), oils (elaioplast), or proteins (proteinoplast).
- Proplastid (n): A small, undifferentiated plastid that can develop into other types of plastids.
Synonyms
- Organelle (a more general term for a specialized subunit within a cell)
- Cellular organelle
Related Phrases and Terms
- Plastid genome: The circular DNA molecule contained within a plastid, which is separate from the nuclear DNA.
- Plastid inheritance: The transmission of plastids (and their DNA) from one generation to the next, often maternally in many plants.
Noun
- any of various small particles in the cytoplasm of the cells of plants and some animals containing pigments or starch or oil or protein