Smt R P Kadam Kanya vidyalay Umbraj TalKarad

Smt R. P. Kadam Kanya vidyalay , Umbraj, Tal-Karad Dist- Satara n. Am. E – sou lohar s. g (B. Sc B. Ed) MOBILE NO-9096234405

7. The Structure of a Cell and Micro-Organisms Std- th 8 Sub- science

Cell Plants, animals, even our bodies are made for a cells

About 350 years ago, in the year 1665, Robert Hooke, an English scientist, observed a thin section of cork under a microscope.

Many small comparytment which names ‘cells’. The study of cells is called cytology. Cells are studied with the help of a compound microscope.

Organelles The cell membrane Cell wall Cytoplasm Mitochondria Golgi bodies Nucleus Vacuoles

The Cell Membrane Funcation of cell membrane 1. cell membraneis the outer covering of a cell. 2. The membrane protects the inner part of the cell. 3. It regulates the flow of substance that enter into and pass out of the cell. 4. It maintains the shape of the cell.

The cell wall Funcation of cell wall 1. I is only found in plant cell. 2. The cell wall gives the cell strength hence the cell gets a definite shape and the inner components get protection

Cytoplasm Funcation of cytoplasm 1. Cytoplasmis a semi fluid substance with water soluble organic and inorganic substances and the various organelles in it.

Mitochondria Function of Mitochondria 1. Mitochondria produce energy from the food material in the cell and supply the energy to the cell when required that is why they are called the powrehouses of the cell

Golgi bodies Funcation of Golgi bodies 1. Golgi bodies are stacks of flat, membranebound sacs in the cytoplasm. 2. They store enzymes.

Nucleus is the central and largest component of the cell. Chromosomes made from DNA are inside the nucleus. Funcation of Nucleus – 1. The nucleuscontrols all the funcation of the cell. 2. It take part in cell division 3. Inherited characteristice

vacuole Vacuole store products of excretion and secretion temporarily.

Digram of plant cell and animal cell

Differences between plant cell and animal cell Animal cell Plant cell 1. There is no covering around the cell membrane. 2. In animal cell vacuoles are small 3. In animal cell there is no chlorophyll 1. The cell wall surrounds the cell membrane. 2. In plant cell vacuoles are large 3. In plant cell there is chlorophyll

Micro organisms There are countless microorganisms all around us in the air, water and soil Types of micro-organisms . Virus . Bacteria Algae fungus Yeast cells Protozoa

Virus A virus has a simple structure without cytoplasm or organelless. . The virus has a covering of protenis. It contains deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) They cause various diseases in plants & animals

Bacteria They are larger than virus but can not be seen without a microscope. In bacteria there are free chromosomes insteads of the nuculeus.

Algae aer found in wet, damp places. The cells of this plants with grow in water contain chlorophyll. They are autotrophic. Most algae are useful. Some kinds of algae serve as a food.

fungus Some fungii are useful while some harmful fungii cause diseases of the skin or damage to substances. These plant cellls do not contain chlorophyll. They grow in damp places on organic substances.

Yeast cells They belong to the class of fungii. Cells cause fermentation caused by some micro-organims results in the formation of organic substances with excellent taste and flavour.

Protozoa This is a class of unicelluler animals. cells do not contain chlorophyll. They have cells membrane and a nucleus. Grow by obtaining ready food materials. they causes illnesses like diarrhoea, vomiting.

Exercises

Choose the right word to fill in the blanks A) The …………is an organelle found only in plant cells. 1)ribosomes 2)mitochondria 3)plastids 4) nucleus B) Chromosomes are found in the organelle called …… 1)plastids 2) mitochondria 3) nucleus 4)Golgi body C) The……. . cell carries out photosynthesis. 1) plant 2) yeast 3) muscle 4)nerve