Cell & its structure & function

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Large variety of organisms on this earth they are all distinct in their form & structure ,yet they all possess similarity in their basic structure & function the bodies of all plants & animals are made up of cell

Defination of cell

Thecell(from Latin cella, meaning "small room") is the basic structural, functional, and biological unit of all known living organisms. Acellis the smallest unit of life that can replicate independently, andcellsare often called the "building blocks of life". The study ofcellsis calledcellbiology.


Cell are the basic structures of all living beings,Yet they remained undiscovered for a long timeThis is becaues the majority of the cell are too Small to be seen by the naked eye it was only After the advent of optical instrument in the17th century, that the study of the cell could be made possible

Robert hooke was the first scientist who observed thin slices of cork through his- self desigined microscopein 1665 (cork is obained from the bark of a treeshe observed honey-comeb like structures consisting of little compartments it was later explained that these compartments were actually dead cell bound by cell wall

Variation in cell number, shape & size in living organisms

Cell number- an amoeba and an earthworm are of different. The size of the organism is due to the number of cells present in them . Amoeba is a living organism consisting of a single cell an earthworm has million of cell hence on the basic of the cell number , living organism can be classified into two categories, i.e unicellular & multicellular

Cell shape-The Size, Shape, And Arrangement Of Bacterial Cells. Most bacteria are 0.2 um in diameter and 2-8 um in length. The three basic bacterial shapes are coccus (spherical), bacillus (rod-shaped), and spiral (twisted), however pleomorphic bacteria can assume several shapes.

Cell size- show on diagram


PART OF CELLCell membrane- all living cell are bound by a membrane called the plasma membrane or the cell membrane it surround the inner gel-like material called protoplasm the plasma membrane controls the entry and the exit of substances according to the requirement of the cell plants fungi and bacteria have an additionl outer covering called the cell wall

Cytoplasma- the portion of the protoplasm lying inner to the cell membrane but outside the nuclear membrane is called cytoplasm it acts as aground substance for all cell activities.it made up of carbohydrates, proteins fats minerals vitamine along with a large proportion of water all these compount works together to provide a unique living nature to the protoplasmNucleus-the central and most important part of an object, movement, or group, forming the basis for its activity and growth. The nucleus is a dense structure bound by a nuclear membrane the protoplasm of the nucleus is called nucleoplasm it has thread like network called chromatinChromosomes-a thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

CELL ORGANELLESPlastide-Anyofseveralcytoplasmicorganelles,suchaschloroplasts,thatcontaingeneticmaterial,haveadoublemembrane,andareoftenpigmented.Plastidsarefoundinplants,algae,andcertainothereukaryoticorganismsandhavevariousphysiologicalfunctions,suchasthesynthesisandstorageoffood.Mitochondria-an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner part being folded inwards to form layers (cristae).

Endoplasmic reticulum (ER)-n. a network of tubular membranes within the cytoplasm of the cell, occurring either with a smooth surface (smoothendoplasmic reticulum) or studded with ribosomes (roughendoplasmic reticulum), involved in the transport of materials..Golgi complex-TheGolgi complex, also known as theGolgiapparatus or simply theGolgi, is a cytoplasmic organelle. It is found in eukaryote cells, as in animals, plants, and fungi. Thecomplexwas discovered by CamilloGolgiin 1898. they are also called the store houes of the cellVocules-amembrane boundcavitywithinacell,oftencontainingawateryliquidorsecretion.minutecavityorvesicleinorganictissue.

Ribosomes-minute particle consisting of RNA and associated proteins found in large numbers in the cytoplasm of living cells. They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins.