Solution : The cell theory was proposed by two scientists- Botanist Theodor Schleiden (1838) and zoologist Matthias Schwann (1839). Main postulates of the Cell Theory : i) A cell is the smallest structural unit of all living things. ii) A cell is the unit of function of all living things. iii) All cells arise from …
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Cell Division New cells are formed in organisms in order to grow, to replace old, dead and injured cells, and to form gametes required for reproduction.The process by which new cells are made is called cell division. There are two main types of cell division: mitosis and meiosis. The process of cell division by which …
Each cell thus acquires its structure and ability to function because of the organisation of its membrane and organelles in specific ways. The cell thus has a basic structural organisation. This helps the cells to perform functions like respiration, obtaining nutrition, and clearing of waste material, or forming new proteins. Thus, the cell is the …
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VACUOLES Vacuoles are storage sacs for solid or liquid contents. Vacuoles are small sized in animal cells while plant cells have very large vacuoles.The central vacuole of some plant cells may occupy 50-90% of the cell volume. In plant cells vacuoles are full of cell sap and provide turgidity and rigidity to the cell.Many substances …
PLASTIDS Plastids are present only in plant cells. There are two types of plastids – chromoplasts (coloured plastids) and leucoplasts (white or colourless plastids). Chromoplasts containing the pigment chlorophyll are known as chloroplasts. Chloroplasts are important for photosynthesis in plants. Chloroplasts also contain various yellow or orange pigments in addition to chlorophyll. Leucoplasts are primarily …
MITOCHONDRIA Mitochondria are known as the powerhouses of the cell. Mitochondria have two membrane coverings. The outer membrane is porous while the inner membrane is deeply folded.These folds increase surface area for ATP generating chemical reactions. The energy required for various chemical activities neededfor life is released by mitochondria in the form of ATP (Adenosine …
Structurally, lysosomes are membrane-bound sacs filled with digestive enzymes. These enzymes are made by RER. Lysosomes are akind of waste disposal system of the cell. These help to keep the cell clean by digesting any foreign material as well as worn-out cellorganelles. Foreign materials entering the cell, such as bacteria or food, as well as …
The Golgi apparatus, first described by Camillo Golgi, consists of a system of membrane-bound vesicles (flattened sacs) arranged approximately parallel to each other in stacks called cisterns. These membranes often have connections with the membranes of ER and therefore constitute another portion of a complex cellular membrane system. The material synthesised near the ER is …
Camillo Golgi was born at Corteno near Brescia in 1843. He studied medicine at the University of Pavia. After graduating in 1865, he continued to work in Pavia at the Hospital of St. Matteo. At that time most of his investigations were concerned with the nervous system, In 1872 he accepted the post of Chief …
Every cell has a membrane around it to keep its own contents separate from the external environment. Large and complex cells,including cells from multicellular organisms, need a lot of chemical activities to support their complicated structure and function. To keep these activities of different kinds separate from each other, these cells use membrane-bound little structures …
