Plastids Part of the plants photosynthesis in eukaryotic cells

 

PLASTIDS - PART OF THE PLANTS

plastid in plants:

Plastids are found in plant cells, but not in animal cells.plastids, are the main sites of photosynthesis in eukaryotic cells. Chloroplasts, as well as any other pigment containing cytoplasmic organelles that enables the harvesting and conversion of light and carbon dioxide into food and energy, are plastids. Plastids were found and named by Ernst Haeckel, yet A.F. W.Schimper Found mainly in eukaryotic cells, plastids can be grouped into two distinctive types depending on their membrane structure: primary plastids and secondary plastids. Primary plastids are found in most algae and plants, and secondary, more-complex plastids are typically found in plankton, such as diatoms and dinoflagellates. Exploring the origin of plastids is an exciting field of research because it enhances our understanding of the basis of photosynthesis in green plants, our primary food source on planet Earth.

 

Types of Plastids:

Proplastids (undifferentiated plastids) may undergo differentiation into many forms, depending upon their specialized functions in the cell. They are, 

1. Chloroplasts

2. Chromoplasts

3. Leucoplasts

4. Proteinoplasts

5. Eliaoplasts

6. Amyloplasts

7. Etioplasts

 

1.Chloroplasts:

A chloroplast is an organelle within the cells of plants and certain algae that is the site of photosynthesis, which is the process by which energy from the Sun is converted into chemical energy for growth. A chloroplast is a type of plastid that contains chlorophyll to absorb light energy.

Chloroplasts are green because they contain the pigment chlorophyll, which is vital for photosynthesis. Chlorophyll occurs in several distinct forms. Chlorophylls a and b are the major pigments found in higher plants and green algae.

 

2.Chromoplasts:

Chromoplasts are plastids that are coloured due to the pigments that are produced and stored inside them. They are found in fruits,flowers,roots, and senescent leaves. The colour of these plant organs is associated with the presence of pigments, apart from chlorophyll.

 

3.Leucoplasts:

Leucoplasts are commonly found in non-photosynthetic plant components such as roots.These are the colourless non-pigmented organelles. Depending on the needs of the plants, they serve as storehouses for starches, lipids, and proteins. They are primarily involved in the conversion of amino acids and fatty acids. The leucoplast diagram would show the exact structure for better understanding.

There are three types of leucoplasts:

· Amyloplasts-Amyloplasts store and synthesize starch.

· Proteinoplasts-They stores the proteins and can be typically found in seeds.

· Elaioplasts-They help in storing fats and oils.

 

4.Proteinoplasts:

Proteinoplasts are specialized organelles found only in plant cells.Proteinoplasts belong to a broad category of organelles known as plastids.leucoplasts stems the subtype, proteinoplasts, which contain proteins for storage. They contain crystalline bodies of protein and can be the sites of enzyme activity involving those proteins. Proteinoplasts are found in many seeds, such as brazil nuts, peanuts and pulses.

 

5.Eliaoplasts:

    Elaioplasts are filled with oils and fatty acids and appear rounded in shape. It serves as a suitable hydrophobic sink for the buildup of carotenoids. Elaioplast is found in the layer of cells of tapetum or tapetal layer in the anther of some flowers in monocotyledons plants, embryonic leaves of seeds, seed endosperms, citrus fruits.The elaioplasts are found mainly in the non-photosynthetic part of the plants monocots and liverworts. Elaioplasts are also responsible for forming fatty acids, lipids, and terpenes in citrus plants. For example, formation during pollen development.

6.Amyloplasts:

Amyloplast is a leucoplast that is primarily involved in storing starch and detecting gravity. As for storing starch, the amyloplasts transform glucose into starch by polymerization of glucose and store the starch grains in the stroma. Most of the amyloplasts can be found in underground storage tissues of plants, such as potato. The amyloplasts, though, can turn into chloroplasts, such as seen in potato tubers that are exposed to light. They become green as the amyloplasts convert into chloroplasts.

 

7.Etioplasts:

Etioplasts are plastids that arise from proplastids. Proplastids give rise to all the plastids in plants. Proplastids that turn into green and become photosynthetic develop into chloroplasts. However, those that are supposed to become chloroplasts become etioplasts when there is no light or when there is low light condition. The etioplast develop from a prolastid when it is grown in the dark. The development into chloroplast is arrested in the absence of light. Nevertheless, the etioplast can be converted into a chloroplast when there is an appropriate light exposure. Light exposure activates the plant hormone cytokinin, which in turn stimulates the synthesis of chlorophyll pigment.

 

Importance of Plastides:

· Plastids store starch and can synthesize fatty acids and terpenes

· They are the site of manufacture and storage of important chemical compounds

· Plastids are responsible for the characteristic colour of leaves, flower and fruit

· They help to trap the sunlight by which chloroplasts make their food by photosynthesis.

   

PLASTIDS
TYPES	MAJOR FUCTIONS
Chloroplast	Photosynthesis lipid synthesis.
Etioplast	Crystalline prolamellar bodies precursor of chlorophyll.
Chromoplast	Pigment synthesis and storage.
Leucoplast	Synthesis of fatty acids and amino acids.
Amyloplast	Storage at starch and sugar.
Elaioplast	Storage of lipids oil.