Cell the structural and functional unit of Life
A cell is the basic structural and functional unit of life which is capable of independent existence all living organisms are made up of one or more cells Organisms consist of only one cell called unicellular and organisms are made of more cells called multicellular.
The human body for example is made of billions of cells every organ of the body contains more than a billion cells.
Cell: Do you know?
• All organisms are made up of cells.
• New sales are arising from pre-existing cells.
• The cell is the structural and functional unit of all living things and organisms.
• The cell contains hereditary information which is passed on from one generation to another during cell division.
• All cells are the same in their chemical composition and metabolic activities.
• Most cells are extremely small and cannot the seen with the naked eye.
• The yolk of an egg is a single cell.
• Most organisms are multicellular.
• All organisms start life as a single cell.
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Research related to cytology (study of the cell)
• The first time Robert Hook observed that the cork was made up of many tiny boxes-like structures and named these structures cell ( Latin cella).
• In 1838 the German botanist Matthias Schleiden proposed that all plants are made up of cells.
• In 1839 Theodor Schwann studied and said that all animals are also composed of cells.
• In 1855 Rudolf Virchow said the cell comes from a pre-existing cell.
Cell theory was rewritten by him in 1858.
Cell structure
Structurally is divided into two main parts.
• Cell membrane
• Protoplasm ( cytoplasm & nucleus)
Cell membrane
The cell membrane also called the plasma membrane, is a very thin, elastic membrane.
It covers the entire surface of the animal cell.
It has fine pores which allow only certain materials to enter and leave the cell.
Therefore, it is selectively semipermeable.
Cell membrane:Function:
• It maintains the shape of the cell
• It permits the growth of the cell
• It allows water molecules to pass through it
• Regulates the chemical nature of the cell with its liquid surroundings medium
Cell wall:
It is only present in plant cells.
It is a wall-like structure, thick and rigid.
It is made of a non-living substance called cellulose the cell wall is not a selectively permeable membrane like a place moment rather it is freely permeable and allows all sources of material to pass through it.
Cell: Nucleus
The nucleus is the largest and most important part of the.
it is a small dense sex generally located at the centre of the cell it is usually spherical.
• The living flute-like structure in the nucleus is called nucleoplasm it is enclosed by a thin layer called nuclear membrane.
• Is nucleus contains a least one nucleolus which takes part in protein synthesis it is made of protein and RNA.
• Is nucleus contains a long thread-like structure called chromatin fibres. It contains chromosomes, and chromosomes have two chromatids attached to the centromere.
• Chromosomes contains jeans it is hereditary they ensure that all new cell produced from them are of the same kind.
Each species has a specific number of chromosomes for example in humans it is 46, mouse 40, monkeys.
54.
Function
• The nucleus controls all the functions of the cell so it is also called the brain of the cell.
• It carries the parental characteristics of jeans to the offspring.
• It plays an important role in cell division.
• It plays a major role in protein synthesis.
Cytoplasm
The cytoplasm is a substance present between the cell membrane and the nuclear membrane of the cell the cytoplasm consists of two main components these are cytosol and cell organelle cytosol is a jelly-like mixture that consists of water, protein, carbohydrate, salt, mineral and organic molecules.
Cell organelles
Endoplasmic Reticulum (ER)
It is a network of tubes which connects the plasma membrane with the nuclear membrane.
It provides a supporting skeleton framework to the cell and a pathway for the transport of substances in the cytoplasm.
Generally, the endoplasmic reticulum is of two types: smooth endoplasmic reticulum and rough endoplasmic reticulum.
The smooth endoplasmic reticulum processes Lipids and carbohydrates, It is involved in the regulation of calcium levels in muscle cells and the breakdown of toxic substances by liver cells.
The rough endoplasmic reticulum is studded with small structures called ribosomes.
Ribosome
These are minute spherical granules-like structures, they are either fond scattered in the cytoplasm or attached to the endoplasmic reticulum they play a major role in protein synthesis.
So ribosomes are also called the factory of the protein.
Golgi apparatus
It is made up of flattened sac-like structures called cisternae.
It is usually found near the nucleus of most of the cells or found scattered in the cytoplasm.
Proteins which are formed in ER are processed in the Golgi apparatus.
After processing, the final product is discharged from the Golgi apparatus.
At this time, the Golgi apparatus bulges and breaks away to form a dropline vesicle.
The vesicles move outward to the cell membrane and either insert their protein contents in the membrane or release their contents outside the cell.
Mitochondria
These are relatively large organised and distributed uniformly in the cytoplasm each mitochondrion is included by an outer membrane and has an inner membrane folded inwards into self-like folds called Christy.
The surface is called exosomes, which secret oxidative enzymes.
Mitochondria are the sides of respiration.
They convert chemical energy contained in the food into a form of energy which is used by the cell to grow divide and function properly.
So mitochondria are also called the powerhouse of this cell they release the stored energy in the form of ATP.
Lysosome
Lysosomes are sac-like bodies containing enzymes that can digest all types of substances.
lysosome digestive waste and harmful material in the cell.
they destroyed the foreign material that entered the cell.
They even digest damaged and dead cells which is why they are called suicidal bags of the cell.
Centrosome
It is a star-shaped minute plan membraneous body found close to the nucleus, in the cytoplasm of animal cells.
Generally, it contains two Road-like small and bright granule bodies called centrioles that are suspended by asters in centrosome centrosomes.
initiate cell division plant cell does not contain centrosome.
Plastid
Plastics are double-membrane disc-like organelles which are found in plant cells there are three types of plastids…….
Leucoplast
These are colourless plastids present in the cells' underground storage part like rhizome tubes in the plant.
they are involved in the storage of food materials such as starch in the plant cell.
Chromoplast
These are non-green plastids that contain red-yellow-orange pigments such as xanthophyll in parts yellow colour, carotene imports orange and lycopene which imparts red colour and anthocyanin which imports blue and violet colour.
they are presented In The petals of the flower and some fruits.
They help in attracting insects for pollination and animals for the dispersal of fruits.
Chloroplast
It is green-coloured plastids which contain chlorophyll pigment in their green.
Each Grannum is a solid flat green body embedded in the liquid Matrix called the stroma.
chlorophyll traps solar energy for photosynthesis they are present in leaves young stones and young fruits.
Vacuole
Vacuoles are non-live fluid-filled LED sacs enclosed by a membrane called tonoplast Most places sell contain at least one large vacuole.
vacuoles store substances such as water glucose protein and sometimes pigment and they also act as reservoirs for harmful waste products formed by plants.
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Q1-what are the cell made of?
Answer-All cells are made from the same major classes of organic molecules: nucleic acids, proteins, carbohydrates, and lipids.
Q2-what are the smallest cell?
Answer-The smallest cell is Mycoplasma gallicepticum. It is about 10 micrometer in size. The largest cells is an egg of ostrich. It is about 15 to 18 cm long and wide.
Q3-who is the father of nucleus?
Answer-Ernest Rutherford, famously known as 'Father of Nuclear Physics' was born on August 30, 1871.
Q4-what are the cell example?
Answer-A cell is defined as the smallest unit of an organism with a nucleus. An example of a cell is a unit in the tissue of an animal muscle. A storm cell. To live in or share a prison cell.
Q5-how cell is formed?
Answer-Two cells are formed from one cell through the process of cell division. In cell division, the DNA within a cell is replicated. The two copies of the DNA are then separated into two different cell nuclei. The cell then splits into two pieces, each piece containing its own set of DNA.
