They were discovered and named by Ernst Haeckel, while A. F. W. Schimper was the first to define plastids.

Origin

Structure

Parts

Different Types of Plastids with Examples

Functions

  1. Intermembrane Space: Present within two membranes with (8-10) nm thickness
  2. Grana: Stacks of membrane-bound organelle called thylakoid. Each granum contains approximately 10-20 thylakoids
  3. Stroma: Cytoplasm of the organelle containing proteins, enzymes, and ribosomes
  4. Peripheral Reticulum: Membranous tubules arising from the inner membrane
  5. DNA: Genetic material of plastids
  6. Ribosome: Organelle where protein synthesis occurs
  1. Chloroplasts: Present in all the green parts of the plant, and blue-green algae. They are green in color due to the presence of the pigment chlorophyll.
  2. Leucoplasts: Non-pigmented organelles that are colorless and are found in the endosperm of seed, roots, and other non-photosynthetic plant parts. Based on the kind of food they store, leucoplasts are classified into the following 3 types:

Amyloplasts Proteinoplasts Elaioplasts

  1. Etioplasts: They are chloroplasts that have not been exposed to light and are a transitional stage between the proplastid and the chloroplast during the process of greening.
  2. Chromoplasts: Present in flowering plants, aging leaves, and fruits. They are colored plastids assuming different colors that develop gradually from chloroplasts with time.
  3. Gerontoplasts: They are chloroplasts that are going through the aging process. Gerontoplasts are present in the old leaves that are no longer performing photosynthesis.
Plastids Definition Structure and Function with Diagram - 40