Plastids with irregular shape:
Plastids are organelles found in the cells of plants and algae. They are responsible for various functions such as photosynthesis, storage of pigments, and synthesis of starch. While most plastids have a regular shape, there are some plastids that have an irregular shape. These include:
1. Chromoplasts: Chromoplasts are plastids responsible for the synthesis and storage of pigments other than chlorophyll. They give fruits and flowers their vibrant colors. Unlike chloroplasts, which have a regular shape, chromoplasts can have an irregular shape depending on the type of pigment they contain.
2. Amyloplasts: Amyloplasts are plastids that store starch. They are commonly found in storage tissues such as roots, tubers, and seeds. Unlike chloroplasts, amyloplasts do not contain pigments and have an irregular shape.
Summary:
Plastids with irregular shapes include chromoplasts and amyloplasts. Chromoplasts are responsible for the synthesis and storage of pigments, giving fruits and flowers their colors. Amyloplasts, on the other hand, store starch and are commonly found in storage tissues.

Plastids with Irregular Shape: Chromoplasts

Chromoplasts are a type of plastids found in plant cells. They are responsible for the synthesis and accumulation of pigments other than chlorophyll. Unlike chloroplasts, which are green and have a regular shape, chromoplasts have an irregular shape and can vary in size and color.

Structure of Chromoplasts:
- Chromoplasts are surrounded by a double membrane, similar to other plastids.
- They contain a matrix called the stroma, which is filled with a gel-like substance.
- Inside the stroma, there are numerous membranous sacs called thylakoids, which are arranged in stacks called grana.
- The thylakoids contain pigments such as carotenoids, which give chromoplasts their various colors, including red, orange, and yellow.

Functions of Chromoplasts:
1. Pigment Synthesis: Chromoplasts are responsible for the synthesis of pigments other than chlorophyll. These pigments play important roles in attracting pollinators and seed dispersers. For example, the red or orange colors of fruits and flowers are produced by chromoplasts.

2. Pigment Storage: Chromoplasts store pigments, such as carotenoids, in their thylakoid membranes. These pigments are important for various physiological processes in plants, including photoprotection, antioxidant activity, and hormone synthesis.

3. Conversion of Chloroplasts: Under certain conditions, chloroplasts can be converted into chromoplasts. This conversion involves the degradation of chlorophyll and the synthesis of new pigments. For example, in autumn, chloroplasts in deciduous tree leaves are converted into chromoplasts, resulting in the vibrant colors of the leaves.

4. Ripening of Fruits: As fruits ripen, chloroplasts in their cells are converted into chromoplasts. This conversion leads to the change in color of the fruit from green to red, orange, or yellow, indicating ripeness.

Conclusion:
Chromoplasts are plastids with an irregular shape and are responsible for the synthesis and accumulation of pigments other than chlorophyll. They play important roles in attracting pollinators, seed dispersal, photoprotection, and the ripening of fruits. By understanding the structure and functions of chromoplasts, we can better appreciate the diverse colors and roles of these fascinating organelles in plant cells.