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Cell Theory Ribosomes and inclusion Bodies 4, , , ibosomes may ‘attach to a single mRN A n, * Schleiden and Schwann together formulated the cell ae 7 polpvibesiat on Soh coenee 4, , theory., * Rudolf Virchow (1855) first explained that cells divided, , and new cells are formed from pre-existing cells (Omnis, cellula-e cellula). He hypothesized:, , * Reserve material in prokaryotic cells is stored in th, cytoplasm in the form of inclusion bodies., , sie : Eukaryotic cells, > All living organisms are composed of cells, andproducts of cells., , , , Include all the protists, plants, animals and fungi, , , , , © All cells arise from pre-existing cells., , An Overview of Cell, , * Eukaryotic cells: Have membrane bound nuclei, * Prokaryotic cells: Lack a membrane bound nucleus, , , , COE et its, , del of plasma membrafie was propose, Ison. 4972). According to this modél, , arranged in mosaic fashion., , , , , , , , , , , if, ave des his model as “protein iceberg in a sé, , , , , * Ribosomes are found not only in the cytoplasm butdise of lipi ds” 4, within the two organelles — chloroplasts (in plants) and — ig, mitochondria and on rough ER. According to the fluid mosaic model, , * Mycoplasmas: Smallest cells (0.3 1m in length) * The plasma membrane is|compbsed of a lipichbi, , , , , , , , , , * Egg of ostrich: Largest isolated single cell, , * Represented by bacteria, blue-green algae, mycoplasma, , and PPLO (Pleuro Pneumonia like organisms)., , « Plasmid: Small circular DNAoutside the genomic DNA., Mesosome: A’ specialized differentiated form of cell, membrane. They are infoldings of cell membrane., , Cell Envelope and Its Modifications, , Consists of'a tightly bourid three layered structure ic., protein, molecules are arranged. i, ‘cocalyx, cellwall and the plasma membrane., , types., , , , , , , , , , , , , , , , different ways:, , se ; : _ (a) Peripheral proteirs\o tri, - .Glycocalyx loose sheath called the slime layer, while These ditdine are |pre a, , ‘ as when it is thick and tough, called the capsule. Wer Sinner, - |. put and Fimbriae: Surface structures known to help > ‘(b), attach the-bacteria-ta:rocks in, streams and Oe
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tions, , » The plasma membrane encloses the cell contents., , It provides cell shape (in animal cells) -e.g.,, , " paracteristic shape of red blood cells, nerve cells, a, , gells. ete., (iii) It allows transport of certain substances into and out, ofthe cell but not all substance, so it is termed selectively, permeable., , (jyyTransport of small molecules (such as glucose, amino, acids, water, mineral ions etc.), , , , , {ethods of cell transpo, ——, , , , Active transport, Requires energy in the, form of ATP, Transport of molecules is, against the concentration, gradient, ie., . from, low to high region of, concentration., , , , , , , , , ransport of molecules is, down the concentration, gradient, i.e., from high to, low region of concentration., , , , , , The active. transport pay, also through a rier, molecule,, , , , , , Two types:, + Diffusion: E.g., absorption, of glucose, , , , , , , , , » Osmosis: Occurs througha |, , , , , , , , , semipermeable membrane. |, , , , , , , , , , , , , , , Cort}, , NET, , * A non-living rigid structure called the cell wall forms, in outer covering for the plasma membrane of fungi and, plants. Bacteria and Protista., , Functions of cell wall, , Cell wall gives shape t the cell, , , , ll interaction and provides barrier to, , wall is, , th, which gradually diminishes as the, , Padle of grow, on the, , ‘| matures and the secondary wall is formed, Ir, ier (towards membrane) side of the cell., *MPosition, , ., , c, , Algg ike, Si Cellulose, galactans, mannans and minerals |, “cium carbonate,, , P| } ;, “nts: Cellulose, hemicellulose, peti and proteins, , : holds. the, , , , , , , , , , , , , , , , , , The endomembrane system include endoplasmic reticulum, (ER), golgi complex, lysosomes and vacuoles., , IE oe a6 OM Le, , , , * The endoplasmic reticulum is a double unit membrane, structure spread all over the cell and occurs in three, morphological forms viz, cisternae, vesicles and, tubules,, , * In muscles, they are known as Sacroplasmic reticulum., , Type of Endoplasmic reticulum, , , , ypes of Endoplasmic reticulum, , , , , , f Smooth ER Rough ER, No Ribosomes on their| Bearing ribosomes on |, surface. their surface., , , , Continuous with the outer, membrane of the nucleus., , | Function: Major site for, synthesis of lipid; synthesis, of lipid-like steroidal, hormones in animal cells., , , , , , Function: Protein synthesis, and secretion, , ¢ Golgi apparatus was discovered by Camillo Golgi (1898), while studying the nerve cell in owl., , , , , , * They consist of many flat, disc-shaped sacs or cisternae, of 0.5um to 1.0um diameter, , * Cisternae are stacked parallel to each other., * The Golgi cisternae are concentrically arranged near the, , nucleus with distinct convex cis or the forming face and, , concave frans or the maturing face., , Materials to be packaged in the form of vesicles from, the ER fuse with the cis face of the golgi apparatus, and move towards the maturing face. This explains,, why the golgi apparatus remains in close association, ‘with the endoplasmic reticulum., , Functions, Sort and package materials, to be delivered either to the, intracellular targets or secreted outside the cell., , * Modify ribosomal proteins in the cisternae before they, , are released from its trans face., , Site of formation of glycoproteins and glycolipids,
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* Lysosomes are the animal cell's digestive organelles., , contains hydrolases - lipases, proteases,, , Lysosomes, , , , dimagatnatca) SO TT, , Help in cleaning up the cell by digesting damaged, material of the cell, , * When cells are old, discased or injured, lysosomes attack, , their cell organelles and digest them. In other words, lysosomes are autophagic, i.c,, self devouring., , Meaty od, , * The vacuole is the membrane-bound space found in the, cytoplasm,, , * It contains water, sap, excretory product and other, materials not useful for the cell,, , * The vacuole is bound by single membrane called, Tonoplast., , * In plant cells, the vacuoles can occupy up to 96 percent, of the volume of the cell., , * In plants, the tonoplast facilitates the transport of a, , number of ions and other materials against concentration, ients inte the vacuole, hence their concentration is, , , , Plastids are found only in a plant cell and euglenvids. They may be colourless or with colour,, , Based on the type of pigments, there are three types of plastids., , , , , , , , , , , , , significantly higher in the vacuole than in the ytopIas,, In Amoeba, contractile vacuole is important for CXcretiee, In protists, food vacuoles are formed by engulfing 4,, food, , Double membrane-bound structure, , The outer membrane and the inner membrane divin,, itslumen distinctly into two aqueous compartments, j_., the outer and the inner compartment., , The inner compartment is called the matrix,, , The outer membrane forms the continuous limiting, boundary of the organelle, , Cristae: Infoldingsin the inner membrane towm:, thematrix; increase the surface area., , The matrix possesses single circular DNA molecule, ribosomes (70S) and the components required for ti,, synthesis of proteins., , Mitochondria are the sites of aerobic respiration. They, produce cellular energy in the form of ATP; hence they, are called ‘power houses’ of the cell, , Acid fuchsin (Triaminotriphenyl methane rosanilinet, It stains parenchyma, cortex, cellulose walls ad, mitochondria., , , , Leucoplast, Whi olourless, Their shapes and sizes varies with, , , , Contains — fat, stored nutrients:, + Amyloplasts, , {starch}, ¢.g., potato., , store carbohydrates, , Elaloplasts store oils and fats, ¢.z.., , , , oil seed, , Aleuroplasts store proteins, ©., maize l 7, Chloroplast, , + Chloroplasts of the green plants are found in the, , mesophyll cells of the leaves., , =.These are lens-shaped, oval, spherical, discoid or even, on-like organelles having variable length (5-10 am), and width (2-4 pm)., , , , , , Chromoplast, Blue, red, or yellow, soluble, , pigments like carotene, xanthophylls, , 3 Chloroplast 2], Green |, Contains chlorophyll and carotenoid, pigments whichare responsible fo, trapping light energy essential fot, photosynthesis., , , , , , carotenoid, , ——e, * Like mitochondria, the chloroplasts are also dosti, membrane bound., , , , * The inner chloroplast membrane is relatively [6°, penneable,, , * The space limited by the inner membrane of, chloroplast is called the stroma.
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number of organised flattened, , membranous sg, alle the thylakoids, are present in ay, , , , The membrane of the thylakoids enclose a space called, , lumen., , he stroma of the chloroplast contains enzymes required, for the synthesis of carbohydrates and proteins., , t also contains small, double-stranded circular DNA, Molecules and ribosomes., , hlorophyltl pigments are present in the thylakoids., , he nhosomes of the chloroplasts are smaller (70S) than, sloplasmic ribosomes (80S)., , , , , , , Ute, , bosomes are the granular structures first observed, der the electron microscope as dense particles by, orge Palade (1953)., , y ure composed of ribonucleic acid (RNA) and, oteins and are not surrounded by any membrane,, , are 80S while the prokaryotic, , k, f, ', , F, f, i, , , , , , , , , An claborate network of filamentous proteinaccous structures, , _ Cytoskeleton,, , F Functions of, , 3 * Mechanical support, , 3 Motility, , spe Maintenance of the shape of the cell., , Cilia and Flagella, , , , , , , , , , , , Cilia are small structures causing the movement of cell or, the surrounding fluid,, , Flagella are comparatively longer and responsible for, cell movement., , The electron microscopic study shows that they are, covered with plasma membrane, , Axoneme: The core of ciliwflagella, containing, microtubules running parallel to the long axis., , 9 +2 array: An arrangement of axonemal microtubules, contains nine pairs of doublets of radially arranged, Peripheral microtubules, and a pair of centrally located, microtubules., , The central tubules are connected by bridges and are, enclosed by central sheath, which is connected to one of, the tubules of each peripheral doublet by a radial spoke., , Thus, there are nine radial spokes,, , The peripheral doublets are also interconnected by, linkers., , Centrosomes and Centrio, , Present in the cytoplasm is collectively referred to as the xy, , Centrosome is an organelle usually containing two, cylindrical structures called centrioles., , They are surrounded by amorphous pericentriolar, matenals, Both the centrioles in a centrosome tie, perpendicular to each other in which each has an, organisation like the cartwheel, , , , , , , , , , , , They are made up of nine evenly spaced peripheral fibrils, of tubulin protein,, , Each of the peripheral fibril is a triplet. The adjacent, triplets are also linked., , ‘The central part of the proximal region of the centriole is, also proteinaceous and called the hub, which is connected, with tubules of the peripheral triplets by radial spokes, made of protein., , The centrioles from the basal body of cilia or flagella, and, spindle fibres that five rise to spindle apparatus during, cell division in animal cells,, , , , , , Nucleus as a cell organelle was first described by, Brown (1831)., , The nucleus stained by the basic dyes was given the nan, chromatin by Flemming. 5 “, , Basic fuchsin is used to stain DNA., , Feulgen reagent devised by Feulgen and Rossenbeck., stains nucleic acid of chromosome,, , Acetocarmine stain nucleus.
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aioe nucleus (nucleus of a cell when it is not, , Shee eatieg ighly extended and elaborate nucleoprotein, : chromatin, nuclear matrix and one or more, , spherical bodies called nucleoli (sing: nucleolus),, , a microscopy has revealed that the nuclear, velope, which consists of two parallel membranes with, 4 space between (10 to $0 nn) called the perinuclear, Space, forms a barrier between the materials present, inside the nucleus and that of the cytoplasm., , * The outer membrane usually remains continuous with, , _ endoplasmic reticulum and also bears ribosomes on, mh, , * Nuclear pores are the passages through which movement, of RNA and protein molecules takes place in both, , , , , , , , , , , , directions between the nucleus and the, , The nuclear matrix oF the nucleoplasm, nucleolus and chromatin. ‘, Nucleolus is a site for active ribosomal RNA sy;, Larger and more numerous nucleoli are p csent, actively carrying out protein synthesis., Chromatin contains DNA and some basic pro, histones, some non-histone proteins and also RI Ni, A single human cell has approximately two metn, thread of DNA distributed among its forty six, three pairs) chromosomes., , Every chromosome essentially has primary cons, ‘or the centromere on the sides of which disc si, structures called kinetochores are present. ,, , Based on the position of the centromere, the chromosomes can be classified into four types:, , , , Metacentric, , Sub-metacentric, , Acrocentric, , Telocentric, , , , A middle — centro, mere forms two, equal arms of the, chromosome,, , Centromere slightly, away from the, middle of the, chromosome, , resulting info one, shorter arm and one, , Centromere is, situated close to, its end forming, one — extremely, short and one, very long arm, , Chromosome has, terminal centromere, , longer arm, , , , , , , , , , , , , , * Sometimes a few chromosomes have non-staining secondary constrictions at a constant location, This gives the appearat, , of a small fragment called the satellite,
