THE STRUCTURE OF A CELL AND MICROORGANISMS Std

THE STRUCTURE OF A CELL AND MICROORGANISMS (Std. 8 th)

Cell organelles Cells have various constituents called, organelles which carry out different life processes. The cell organelles are as follows: 1)Cell membrane 2)Cell wall 3)Cytoplasm 4)Mitochondria 5)Golgi bodies 6)Ribosomes 7)Lysosomes 8)Plastids 9)Nucleus 10)Vacuoles.

Functions of cell organelles 1)Cell membrane Structure- Thin, flexible outer covering of the cell. Functions 1) Protects inner parts of the cell. 2) Regulates the flow of substances that enter into or pass out of the cell. 3) Maintains the shape of the cell.

2)Cell wall Structure- Present only in plant cells. It is made up of cellulose. Functions- 1)Gives strength to the cell. 2)Substances can pass into the cell or out of the cell through the cell wall. 3)Gives a definite shap to the cell. 4)Protect inner components of the cell.

3) Nucleus Structure 1)Centeral, round and largest part of the cell. 2)Porous nuclear membrane around it. 3)Inside it, are chromosomes made up of DNA and genes. Function 1) Controls all the functions of cell. 2) Takes part in cell division. 3) Transmits inherited characters through DNA and genes.

4) Cytoplasm Structure-1) Substance filling the cell, apart from the nucleus. 2) Semi-fluid substance with water soluble organic and inorganic substances. Function 1) Cell organelles which perform all the functions of the cell are embedded in it. 5) Mitochondria Structure-1) Mainly tubular in shape. 2) It has double walls. 3) Inner wall has folds. Function 1) Produce energy from the food material in the cell. 2) Supply energy to the cell whenever required.

6) Golgi bodies Structure. Stacks of flat, membrane bound sacs Function 1) Storage of enzymes. 7) Vacuoles Structure 1) An empty space covered by a single membrane. 2) Plant cells have larger and more vacuoles than the animal cells. Function They store products of excretion and secretions.

- Presented By - Miss. Patil Preeti Mohanrao (B. Sc. B. Ed. )