Anas Zoology

 It is the most accepted model of Plasma Membrane/Cell Membrane. It was proposed by Singer and Nicolson in the year 1972. Phospholipids form bilayer in the centre. their unsaturated fatty acids forms the tail and glycerol forms the head, which prevents the close packing of the molecules. Phospholipids show two types of movements: Transition and Flip-Flop movement. Transition: Molecules change their position in the same layer. Flip-Flop: Molecules interchange between two layers. There are two types of proteins in cell membrane/plasma membrane Extrinsic/Peripheral proteins - Form 30% of the total membrane protein, superficial, easily removed, some are covered by glycolipids/glycoproteins. They provide structural and functional specificity to the membrane. eg. ATPase, spectrin, acetycholinesterase etc. Intrinsic/Integral Proteins - Form 70% of the total membrane proteins, embedded in lipid bilayer, can be extracted by rupturing membrane, held in position by polar and nonpolar side of phos

A) Danielli - Davson Model / Sandwich Model / P-L-P Model: This model of plasma membrane was proposed by Danielli and Davson in the year 1935. According to this the plasma membrane is trilaminar, where lipids bilayer is sandwitched between the two protein layers. Hence it is also called as P-L-P model (P=protein, L=lipid). This model fails to explain functional specificity and active transport through membranes. B) Unit Membrane Model / Robertson Model: This model of plasma membrane was proposed by Robertson in the year 1959. According to Robertson, all membranes have the same basic structure but they have their own distinctive composition. Example: Internal organelles have more proteins than lipids in eukaryotic cells whereas plants and bacteria have more lipids than proteins. This model fails to explain the membranes stability and permeability. Related Articles: 1) Biomembranes https://anaszoology.blogspot.com/2022/08/biomembranes.html

Biomembrane/Biological Membrane is a semipermeable covering around the cell and organelles, which separated them from the external environment. Biomembrane which covers the cell is called a cell membrane/Plasmalemma, biomembrane which covers the organelle is called subcellular membrane. Composition of Biomembrane Biomembranes are tripartite or trilaminar i.e. made up of three layers Proteins : 59-75% fibrous or globular proteins Lipids : 20-40 % Phospholipid, sterol, glycolipid, sphingolipid Carbohydrates : 1-5% Hexose, hexamine, sialic acid Functions of Biomembranes: Helps to transport the solutes across the membrane. Biomembrane only allow certain types of molecules to enter the cell and organelle, they keep the toxins from entering into the cell. The receptors present on biomembranes helps the cells to communicate.

  An important tool of molecular biology is DNA fingerprinting. It is a way to distinguish individuals as it is unique for every living being (except clones) and cannot be altered by any process. Applications of DNA Fingerprinting: Paternity Test - The DNA fingerprint of child is matched with the prints of parents to determine family relationships. In parental disputes this technique is used to determine the true parents of the child. Criminal identification - DNA fingerprint from blood/hair/semen of suspect is picked up from the scene of crime, prepared and compared with the sample collected from scene. Many cases have been solved by this technique. Study Evolution - It is helpful in finding out genetic relationship between different races of man. Related Articles: DNA Fingerprinting:  https://anaszoology.blogspot.com/2022/08/dna-fingerprinting.html

An important tool of molecular biology is DNA fingerprinting. It is a way to distinguish individuals as it is unique for every living being (except clones) and cannot be altered by any process. All segments of DNA do not code for protein. Some segments have regulatory function, others are Introns (Interviewing sequence/IVS) still others are repetitive DNA sequences/Mini satellite sequences . The most important segment for DNA fingerprinting are short repetitive nucleotide sequences which vary from person to person. These are also called Variable number tendem repeats (VNTR). To prepare a DNA fingerprint a small amount of saliva/blood/hair/semen or any other cell of the body is required. Steps of DNA fingerprinting are as follows: Extract the DNA from the sample. If DNA is not sufficient, amplify it using PCR i.e. make more copies of DNA using PCR. Cut DNA with restriction endonucleases. The cut segments possess DNA of different length in different individuals called restriction length

 The organisms whose cells contain a membrane bound nucleus and membrane bound organelles are called a eukaryotes. Structure of Eukaryotic Cell Characteristics of Eukaryotic Cell: Cell size and volume depend on the activities performed by it (5 - 100 μm). Cellulosic cell wall is present only in plant cells. Capsule is absent. Mesosome is absent. Well organized nucleus is present. Mononucleate condition is more common. DNA is linear and is covered by histonic protein (except in mitochondria and plastid). Monocistronic DNA is more common. Three kinds of RNA polymerase are present. One for each - rRNA, mRNA, tRNA. Transcription occurs in the nucleus and translation in the cytoplasm. Extranuclear chromosome are absent. Ribosome is 80S (60S + 40S). Protein synthesis is inhibited by cyclohexamide. All organelles are present. Cilia and flagella show characteristic 9+2 arrangement of microtubule and are made up of protein tubulin. Microfilaments are present. True sap vacuoles are common in pla

A prokaryote is a single celled organism that lacks a true nucleus and other membrane bound organelles. Structure of Prokaryotic Cell Characteristics of Prokaryotic Cells:  Cell is small in size (0.1 - 5 micrometers). Cell wall is made up of muramic acid (amino acid derivative of peptidoglycan). In many cells mucopolysaccharide capsule is present. Mesosomes controls cellular respiration and cell division. An organised nucleus is absent. DNA is circular and naked. Usually polycistronic DNA is present. Only one kind of RNA polymerase is present. Transcription and translation both occurs in the cytoplasm. Extracellular chromosomes are present in the form of plasmid or episome. Ribosome id 70S (50S + 30S) Cytoplasm lack cell organelles. If flagella is present, it is made up of single stranded protein called flagellin. Microfilaments - Actin and myosin are absent. Sap vacuoles are absent instead they have gas vacuoles. Endocytosis and exocytosis are absent. They divide by amitosis or simple

  What is Mutualism ? It is a positive relationship between two individuals of species where both the species are benefited. Examples of Mutualism: Pollination by Animals: animals like bees. butterflies and moths derive their food from plants and brings about the pollination of plants. Ants feed on honeydew produced as a waste product by aphids and in return offer them protection. Oxpecker feeds on ticks and blood-sucking flies from the body of large grazing mammals like zebras, buffalos, rhinos etc. This helps the large mammals from getting infected by such parasites and in return oxpecker's gets an easy meal. Oxpecker and Buffalo (Image taken from: https://www.youtube.com/watch?v=5MfrsKJailo)

What is Commensalism ? Commensalism is a positive interaction and a symbiotic relationship between two species in which one species benefits and the other neither benefits nor is harmed. Three terms are used to describe different types of commensalism Inquilinism: When one species uses other species for shelter. Example: Woodpecker drilling a hole in cactus to use it as a nesting site. The cactus is unaffected while the woodpecker is benefited. Phoresy: Occurs when one organism uses a second organism for transportation. Example: The Bromeliad treefrog carry ostracods from one bromeliad plant to another. Metabiosis: Occurs when one organism uses something produced by the first, usually after its death. Example: Hermit crab using the shell of a dead gastropod for protection. Other examples of Commensalism: Vultures feeds on the leftovers of kills of carnivores and other dead animals. It is a type of commensalism since vultures benefits without affecting the dead animals. The fish remora

  What is Parasitism ? Parasitism is a type of relationship between species in which one organism is benefited while the other organism is harmed. The organism that is benefited is called as parasite and the one that is harmed is called as host. Types of Parasite: On the basis of size parasites are classified into two types: Microparasite: They are characterized by their small size. Microparasite include bacteria, viruses and protozoans. Macroparasite: They are relatively larger as compared to microparasite. Macroparasite include flatworms, ticks, roundworms, fleas, lice and flukes. Parasites are classified into two types depending on where they live Ectoparasite: The parasites that live on the surface of the host are termed as ectoparasites. Mite, flea, ticks, lice etc are ectoparasites. Tick (an ectoparasite) Endoparasite: The parasites that live inside the body of the host are termed as endoparasites. Plasmodium, amoeba, roundworms etc are endoparasites. Roundworm (an endoparasite)

  What is Neutralism? Neutralism is a type of symbiotic relationship in which two different species are not affected by association with one another. (Both the populations do not affect each other) The term Neutralism was introduce by Eugene Odum an American biologist Examples: 1) Grass Carp and Catla residing on the surface of a pond do not affect one another as their food habits are different. Grass Carp feeds on macro vegetation while Catla feeds on zooplanktons. Grass Carp Catla                        

Skeleton includes bones and cartilages. Definition of Bone Bone is a living tissue that makes up the skeleton of the body. Composition of Bone: Bone is composed of inorganic calcium salts. It consist mainly of calcium phosphate and partly of calcium carbonate. The inorganic calcium salt is calcium hydroxy-apatite [Ca 10 (PO 4 ) 6 (OH) 2 ] It also consist of the organic connective tissue made up of collagen fibres. Functions of Bones: It gives shape and support to the body. Bones contain bone marrow. Bone marrow contains the reticuloendothelial cells, these cells are phagocytic in nature and take part in immune responses of the body. Bone marrow also helps to manufacture the blood cells. Bones provides the surface for the attachment of muscles, tendons and ligaments. They store about 97% of the body's calcium and phosphorous. They protect the vital organs of body e.g. Skull protects the brain, vertebral column protects the spinal cord. 

 Animals are metazoans that differ from plant in number of characteristics like absence of plastids, cell wall and central vacuole. There are around 1.2 million known species of animals, but scientists estimate there are closer to 8.7 million species on earth. they show great diversity in shape, size, colour, habits, habitat, structures etc. CHARACTERISTICS OF ANIMALIA: They are multicellular consumers of the ecosystem. They are made up of eukaryotic cells and have no cell wall, plastids, central vacuole and photosynthetic pigments. Lower animals exhibit cellular or tissue level of organization and higher animals have organ system level of organization. Mostly free living and some are fixed (sponges and several coelenterates). They take food by ingestion i.e. holozoic in nutrition and digestion takes place in an internal cavity. Some forms have absorptive nutrition and their digestive cavity is absent. The undigested food is removed by egestion.  They have muscle cells (for contraction

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