Anas Zoology

PROKARYOTES: Cell is small in size (0.1 to 5 μm) Cell wall is made of non cellulosic material. They generally contain muramic acid (amino acid derivative-peptidoglycan). Mucopolysaccharide capsule is present in many cells. Cell membranes infolds to form mesosomes that controls cellular respiration and cell division. An organized nucleus is absent. Here chromatin network is in direct contact with cytoplasm. It is called nucleoid / genophore. Mostly prokaryotes have multiple nucleoids. DNA is circular and naked. Usually polycistronic DNA is present. Only one kind of RNA polymerase is present. Both transcription and translocation occurs in the cytoplasm. Generally extranuclear chromosomes are present either in the form of plasmid or episome. Ribosome is 70S (50S + 30S) Protein synthesis is inhibited by chloramphenicol. Cytoplasm lacks membrane bound organelles. Flagella if present is mad up of single stranded protein, flagellin. Microfilaments - Actin and Myosin are absent. Sap vacuoles a

 The skin and their associated structure make up the integumentary system. Skin protects terrestrial organisms from desiccation and from heat loss. The largest organ of mammal is skin. It protects the body against physical,chemical, and biological attacks, it helps to regulate body temperature, it is used to communicate to other individuals, and a skin derivative provides nourishment for the young. Mammal skin is composed of two layers, the dermis and the epidermis. Below the dermis there is a layer known as hypodermis, some may consider this as the third layer of skin. HISTOLOGY OF SKIN : Skin has four layers of cells is referred to as thin skin. From deep to superficial, these layers are the stratum basale, stratum spinosum, stratum granulosum and stratum corneum. Most part of the skin can be classified as thin skin. Thick skin is found only on the palms of the hands and the soles of the feet. It has a fifth layer, called the stratum lucidum, which is located between the stratum corn

 1) SQUAMOUS EPITHELIUM: It is a type of simple epithelial tissue. It forms the lining of the oral cavity, oesophagus, alveoli of lungs, blood vessels, kidney tubules etc. The cells are polygonal, flattened and resting over a basement membrane. They look like the tiles of a floor, hence are also called as pavement epithelium. Each cells shows a clear cytoplasm with the nucleus in the centre. The cells are closely packed with very little intercellular substance called matrix. They form a thin sheet and provide protection to the underlying tissue. 2) MUSCLE FIBRE: A) Smooth/Unstriated Muscle Fibre: It is a type of muscular tissue in the visceral organ. It occurs in the forms of layers or bundles in the wall of the hollow organs like the alimentary canal, blood vessels, trachea, urinary bladder. The muscle cells(fibres) are spindle shaped, tapering at both the ends and broad in the centre. Each cells shows a central nucleus surrounded by cytoplasm called sarcoplasm. There are myofibrils i

 Blood is a red coloured viscous fluid in vertebrates including man. The blood consists of a suspension of cells called the corpuscles (RBC's, WBC's and platelets) in the plasma. The plasma constitute 55%of the total human blood whereas the blood corpuscles make up the remaining 45%. The ratio of the red blood corpuscles to the plasma is expressed as the haemotocrit  value or haemotocrit.  The general composition of whole blood is as follows: A) Cells: RBC's, WBC's and Platelets B) Plasma: Water 92% remaining 8% consist of : a) Proteins: Serum albumin, serum globulin, fibrinogen, prothrombin. b) Organic substances other than proteins: glucose, amino acids, fats, phospholipids, neutral fats, cholesterol and cholesteroids. c) Inorganic substances: chlorides, carbonates, bicarbonates of Na, K, Ca, and Mg. d) Various antibodies, hormones, enzymes etc. e) Waste materials: urea, uric acid, ammonia, creatinine, xanthene etc. f) Colour compounds: The yellow colour of plasma is

  It is the arrangement of body parts on two sides of main axis of body. animals can be categorized on the basis of body symmetry as follows: ASYMMETRICAL  : Body is highly irregular that it cannot be divided into two similar parts by any plane e.g. snails, sponges,  Amoeba SYMMETRICAL :  The body can be divided into two similar parts by one or more planes (a) Spherical / Universal Symmetry :  The body is like a ball and can be divided into two equal parts by any plane passing through the centre of the body e.g.  Volvox,  some corals. (b)  Radial symmetry :  The body is in the form of a flat or cylinder (tall). It can be divided into equal halves by any plane passing through the centre from top to bottom e.g. some sponges,coelentrates, echinoderms. Their types are as follows: (i)   Tetramerous Radial Symmetry :  Body parts are arranged in 4 or multiple of 4 e.g. Jellyfish (ii)   Pentamerous Radial Symmetry :  Body parts are arranged in 5 or multiple of 5 e.g. Echinoderms (iii)  Hexamer