Anas Zoology

  Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER) is a system of sac like structures and tubes found in all eukaryotic cells. They are known as sarcoplasmic reticulum in skeletal muscles, Nissl granules in neurons and myeloid bodies in retinal pigment cells. They are absent in RBCs, eggs and embryonic cells. Endoplasmic Reticulum arise by evagination of nuclear membrane. Endoplasmic Reticulum have three parts: Cisternae: It is a sac like, parallel tubules having ribosomes on their surface. It is unbranched. Tubules: It is tube like, irregular, branched and without ribosome. Vesicles: They are round or spherical, without ribosomes Parts of Endoplasmic Reticulum . There are two types of endoplasmic reticulum  Rough Endoplasmic Reticulum (RER): They have ribosomes on their surface. The 60S unit of ribosomes are attached to the ER by means of a protein ribophorin I and ribophorin II. Number of cisternae and tubules are more. They are abundant near the nuclear membrane. ...

  Cytoplasm: Cytoplasm is the protoplasm present within the living cell, excluding nucleus. Cytoplasm is enclosed within cell membrane. Cytoplasm can be differentiated as: Cytoplasmic matrix / Cytosol / Hyaloplasm Cell inclusions Cell organelles Cytoplasmic Matrix: The Cytoplasmic matrix is the the gel like substance present in cytoplasm. It is more dense and viscous than the cytoplasmic fluid. Cytoplasmic matrix contains enzymes for synthesis of carbohydrates, fats, amino acids and proteins. Cell Inclusions: Cell inclusion are the non-living substances of cytoplasm. They may be in the form of reserve food, minerals, excretory and secretory products. Some of these are: 1) Starch grains: Exists as eccentric of concentric rings around proteinaceous hilum. It is stored in rhizomes, potato, rice, maize etc. Starch Grains around hilum 2) Fat droplets: They are present in animal cells in the form of adipocytes. Fat droplet in the cell 3) Glycogen granules: They are present in liver and m...