STUDY OF CELL CONSTITUENTS AND CELL INCLUSIONS - EXPERIMENT

The cell theory states that plant or animal body is ultimately made up of minute cells and concluded that the cell is the structural unit of life.

The living organisms are of two types either unicellular or multicellular.

            In multicellular organisms the life activities are performed by co-ordination of several organs, these organs are made up of tissues, while the tissues are aggregates of similar cells.

            In unicellular organism all activities are performed by same cell.

Shape: The cell has definite shape of its type with few exceptions like amoeba, leucocytes etc. various shapes like oval, spherical, polyhedral, columnar, cylindrical, stellate and several others are found in plants as well as in animal cells.

Size: Normally the size may varies from 0.5 to 20µ and vary up to 200 to 300 mm as in case of plant fibers and latex cells.

                                

Types of cells:

There are two types of cells

·         Prokaryotic

·         Eukaryotic

Prokaryotic cell

·         Prokaryotic type of cells are characterized by the absence of true nucleus, obviously the nucleolus and nuclear membrane.

·         DNA is without protein sheath and nuclear matter is in direct contact with the cytoplasm.

·         The ribosome are scattered in the matrix while other organells and pigments are present.

·         Meiosis and mitosis are not observed. 

·         Eg: Blue green algae, bacteria etc

Eukaryotic cell

·         All plant and animal cells belong to eukaryotic type of cells.

·         Eukaryotic type of cells are characterized by the presence of well marked true nucleus, nuclear membrane, Distinct nucleolus in the nucleus, while plastid and mitochondria are represented with protein sheath

·         DNA is covered with protein sheath.

·         Endoplasmic reticulum associated with ribosome is present in the cytoplasm.

·         Cell wall is made up of cellulose.

·         Meiosis and mitosis are observed in this type of cell. 

Functions:

Cell wall:

·         It offers rigid frame work and protection to protoplast.

·         Thick and lignified cells of the plant provide mechanical support to the organ.

·         Checks the rate of transpiration due to cuticular sheath.

·         Prevents the distention of protoplast by developing wall pressure.

·         Due to various contents like cutin, lignin, wax etc the cell wall results in permeability which is ultimately responsible for life of cell.

Plasma membrane:

·         Because of permeability it controls transport of material across it.

·         Permit diffusion of water and fat soluble components.

·         Fat insoluble components pass through the membrane by forming reversible compounds with membrane proteins.

Endoplasmic reticulum:

·         Due to ribosome, it is involved in protein synthesis, also in glycogen and fat metabolism.

·         Gives mechanical support to cytoplasm.

·         Participate in exchange of materials by active and passive transport.

Ribosomes:

Degradation and synthesis of proteins takes place in ribosomes.

Golgi complex:

·         Condensation of lipids, carbohydrates hormones takes place in golgi bodies.

·         Participates in the formation of lysosomes.

Mitochondria:

·         Mainly responsible for transformation of chemical energy into biological energy in the form of ATP compounds.

·         All enzymes involved in Kreb’s cycle are present in mitochondria.

·         It is also responsible for transmission of hereditary characters..

Nucleus:

·         Controls all activities of the cell.

·         Biogenesis of ribosome takes place in nucleolus only.

·         Nucleolus take part in cell division.

Chromosomes:

·         They play very important role in heredity, mutation and variation.

·         Chromosome have capacity of self reproduction.

CELL INCLUSIONS: (Ergastic substances of plants)

The non living substances of plant metabolism are known as ergastic substances. They may be reserve foods, secretary and excretory or end products of metabolism.

A)    Reserve foods

1) Carbohydrates: Group of compounds composed of carbon, hydrogen and oxygen in which the later two elements are in same proportion, they are polyhydroxy aldehyde or polyhydroxy ketone or the compounds that on hydrolysis produce either of the above. Many water soluble, as well as water insoluble carbohydrates are found in plants. Glucose, fructose and sucrose are water soluble. The water insoluble contents are normally poly-saccharides.

Inulin: It is the only polysaccharide soluble in water and is found in tubers of Dahlia and Dandelion. In alcohol it forms sphere crystals.

Starch: It is another poly saccharide mostly found in tubers, food grains and seeds of the plant. It is found in the form of granules, concentric and eccentric. Starch gives blue color with dilute solution of iodine.

Cellulose: a complex polysaccharide forming cell wall and is structural material of plants. Mucilage in senna, isapgol, and lined, forming gummy solution in epidermal cells is another example of polysaccharide.  

2) Proteins: These are the complex nitrogenous organic substances of plants and animals origin. They are either soluble or insoluble in water. They are of great importance in the structure and functioning of living cells. They are produced by and associated with living matter. They may be amorphous or crystalline.

In maize they are amorphous or crystalline. In maize they are amorphous found in the form of layers as aleuron layer or crystalline as aleuron grain in castor seeds. They are converted to amino acids by proteolytic enzymes.

3) Lipids: Lipids are the substances obtained from plants and animals comprises of fixed oil, fats and waxws.These are reserves of food material of plants. Those which

are liquid at room temperature are called as oils and solids are called as fats. They are made up of fatty acids and glycerine. Oils are found in endosperm of the following seeds of castors, pea nut and sesame.

B) Excretory products:

1) Alkaloids: These are the basic nitrogenous organic compounds obtained from plan, animal or minerals also can be synthetically prepared, contains at least one nitrogen in side the hetrocyclic ring or out side the hetro cyclic ring and which after administration in very small dose produces an immense pharmacological action. They occur in plants as salts of nicotinic, quinic, citric or oxalic acid. They are found in seeds, bark, leaves, roots etc. alkaloids are used as highly potential medicaments and possess curative properties. They are protective materials of plants. Alkaloids are reservoirs of protein synthesis. In large doses they are poisonous.

Eg-Caffeine, Quinine, Morphine, Reserpine, Strychnine, Vincristine.

2)   Glycosides: Glycosedes may be defined as organic compounds obtained from plants and animal sources which upon acidic or enzymatic hydrolysis gives one or more sugar moities along with non sugar moities. The sugar part is called as glucose or the non sugar part is called as aglycone or genin.They are condensation products of sugar and nonsugar. They are also secondary metabolites and are also poisonous. These are soluble in water as well as alcohol they got wide range of medicinal properties.

Eg- Senna, Digitalis, Bitter almond, liquorice etc.

3)   Tannins: Tannins are secondary metabolite present in cell saps and in distinct vacuoles ment for its astringency properties and also has an capacity to combine with tissue protein and precipitate them. soluble in water and alcohol. They gives blue black or green color with iron compounds. They have several medicinal properties.

Eg-Nutgall, Myrobalan,Black catechu,pale catechu

4)   Resins: Resins are the amorphous products of complex chemical nature these are amorphous mixtures of essential oils, oxygenated products of terpene and carboxylic acids found as exudation from trunk of various trees.These are found in abundance in the trunks of the trees in the resin ducts or in rhizome(Ginger), fruit(Capsicum) and other parts of the plants. They are insoluble in water, may be semi solid or solid. Many times they get associated with gums or volatile oils.

5) Latex: It is white suspension where in microscopically small particles or oil globules are suspended. They contain protein, sugar, minerals and alkaloidal salts in true solution, while gums, srtarch, resin, are in suspended form. Latex is present in lacteciferous tissue characteristic to certain families like euphorbiaceae, cariceaceae, papavaraceae etc.

Eg-Papaya, Ficus, Poppy.

6) Volatile oils: These are odorous volatile principles of plants and animals, they evaporates on exposure to ordinary temperature. These are the fragrant liquids found in plants. They are volatile, liquid and aromatic and are present in roots, leaves, barks, fruits, they are insoluble in water and soluble in alcohol. Normally volatile oils are carminatives, stimulant and antiseptic

eg- Fennel,Orange, Lemon, Coriander, Cinnamon, Ginger, Eucalyptus and Mentha.

7) Mineral crystals: These occur in cell wall or cell cavities. They are in soluble in water common crystals are calcium oxalate, calcium carbonate and silica. They are found in roots, stem, leaves, fruits, etc various types of crystals of calcium oxalate are found like prism, acicular, raphides, clusters, rosettes, etc.

C) Secretary products:

Various other products not covered under any one of above types, are formed in the plants and served some important functions in plants and are the secretary products. Eg-Enzyme, coloring substance, nectar

Enzymes are the nitrogenous water soluble compound carrying out hydrolysis of carbohydrate and proteins. Coloring substance or pigments like chlorophyll are essential for photosynthesis, anthocyanins and several others, nectars is the sugary solution secreted by many flowers in special cells or glands to attract the insects for effective pollination.