Zoology

Chloroplasts

Chloroplasts: Definition, Structure, Functions

Chloroplasts are double membraned rod-like oval or spherical cell organelles in the cytoplasm of most plant cells that help in photosynthesis. It is a green plastid containing chlorophylls. Animal cells normally lack plastids(all forms of plastids including chloroplasts). Several unicellular…

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Mitochondria

Mitochondria: Definition, Structure, Functions

Mitochondria are the rod-shaped, ovoid, or thread-like, scattered minute particles in all aerobic cells of higher animals and plants. These are also present in algae, protozoa, and fungi. Bacterial cells, however, do not have mitochondria. They are associated with cellular…

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Ribosomes

Ribosomes: Definition, Types, Structure, Functions

Ribosomes are membraneless, small, sub-spherical ribonucleoprotein particles. They are often found connected to the outside of the endoplasmic reticulum and nucleus. Ribosomes also occur freely in the cytoplasm (cytoplasmic matrix), chloroplasts, and mitochondria. In 1943, A. Claude has first isolated…

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Lysosomes

Lysosomes: Definition, Structure, Functions

Lysosomes are tiny vascular membrane-bound vesicles involved in intracellular digestion. They contain a variety of hydrolytic enzymes that remain active under acidic conditions. Greek words “Lysis = digestive or break down, and soma = body“. During electron microscopic studies in…

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