Cephalochordata (Gr., kephale, head; chorde, cord) is a sub-phylum within the phylum Chordata. The animals in this group are small, marine invertebrates. They are commonly called lancelets or amphioxi. Cephalochordates show many typical chordate features, including a notochord, a dorsal…
The sub-phylum Urochordata (Gr., uro, tail; chorde, cord) is a part of the phylum Chordata. The animals in this group are called sea squirts,or tunicates. These animals are very unique and show a high degree of diversity in their form,…
Phylum Hemichordata is generally considered the sister group of the phylum Echinodermata. The animals are marine deuterostomes. They are more or less worm-like, having the ancestral tripartite body of proboscis, collar, and trunk. The name Hemichordata is derived from the…
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…
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…
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…
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…
The Golgi apparatus or the Golgi body or Golgi complex or simply the Golgi is a complex cytoplasmic structure having relation to cellular secretion. Which consists of vesicles and vacuoles, with smooth cisternae and a network of tubules. In 1898,…
Sterilization is the complete eradication of microorganisms (fungi, bacteria, and viruses) present on the surface of any material. The microorganisms can be removed or destroyed from the definite materials (seeds, leaves, root pieces, stem pieces) by using sterilization techniques. Objective…
The Eukaryotic cell is the most advanced type of cell which is present in both animals and plants. Dougherty (1957) has divided cells into two types (based on the organization in the nucleus of the cell) – The Prokaryotic cell…