Cell (plant - animal) organelles | its Organelles | how it Organelles works?

-Cell Organelles 

     An organelles is a unit inside the the cell that perform a special function.the  various functions are performed by a cell are actually divided among the organelles, that is,there is a division of labour is absent inn prokaryotic celols.for example,energy production is performed by  mitochondria, photosynthesis by plastid,etc. the various cytoplasmic organelles are given below :

 - Endoplasmic reticulum

        it is a large network or reticulum of membrane-bound organelles tiny tubular structures that start at the nuclear membrane and extend into the cytoplasm.they mainly involved with the synthesis, folding, modification,and transport of protien.

  a- Rough endoplasmic reticulum ((RER) - it possess ribosomes on its surface and help on Protein synthesis,

  b- Smooth endoplasmic Reticulum (SER) - It lacks ribosomes on it surface, thet are a major site for lipid synthesis and also involved in the detoxification of toxic poisons.

 - Ribosomes 

          It consists of dense and spherical particle in both prokaryotic and eukaryotic cells. these are the site of protein manufacture. They are found either free in the cytoplasm or attachd with the rough endoplasmic reticulum. These are not bound by any membrane and are complex of ribo nucleic acid (RNA) and protein. 

 

- Golgi Apparatus

           It was first described by Camillo golgi in 1898. It consists of a system of many, flat disc-shaped sacs called cisterna, which are arranged parallel to each other. its function include packaging, storing and dispatching of various products recieved from endoplasmic reticulum. It remains in close association with endoplasmic retticulum.It is involved in synthesis of complex sugars and lysosome.

 - Lysosomes

             These are composed of tiny spherical structures surrounded by a single membrane. They contain many digestive enzymes that are manufactured in Rough Endoplasmic Reticulum. Lysosomes are known as waste disposal system of the cell as they help in cleaning the cell by removing worn out or damaged cellular organelles. They are also called the suicide bags of the cells as they can digest their own cell, if anything happen to the cell structure or if the cell gets damaged. 

 -  Mitochondria

            They are referred to as the powerhouse of the cell. They are the main sites of protein production. They are produce energy in the form of Adenosine Triphosphate (ATP). ATP is also known as the energy currency of the cell. The Number of mitochondria person cell vary according to the physiological activity of the cell. 

    Structure of a typical mitochondria is characterized by the following features. 

• It is surrounded by a double membrane covering 

• It's outer membrane is porous and inner membrane is deeply folded. 

• The folding of inner membrane are called cristae which increase the surface area. 

• The compartment enclosed by inner membrane is called matrix. 

• Mitochondria possess it's own DNA and ribosomes. 

 -  Plastids 

       Plastids are present in most plant cells and are absent in animal cells. Like mitochondria. Plastids contain their own DNA and Ribosomes. Plastids are of three types. 

    1- Chromoplast

    2- Chloroplast 

    3- Leucoplast

 1:- Chromoplast :- Coloured plastids in which chlorophyll is absent and contain yellow or orange pigment. They are found in fruits, flowers, etc. 

 2:- Chloroplasts :- Consist of a green pigment called chlorophyll and it mainly function in photosynthesis. Chloroplast is also known as Kitchen of the cell. 

 3:- Leucoplasts :- They are white or colourless and mainly function in storage. Depending upon the storing material, leucoplasts are of three types: Aleuroplast (stores protein), Amyloplast (stores carbohydrates), Elaioplast (stores oil). 

-   Chloroplast

            It is surrounded by a double membranes covering. It consist of many membrane - bound flat discs called thylakoids which have chlorophyll. thylakoids are arranged in stacks called grana. The matrix found inside the chloroplast is called stroma. Thylakoids of different grana are connected by stromal lamellae. 

-   Vacuoles

          These are membrane - bound spaces seen in the cytoplasm of mainly plant and fungal cells. These are the storage sacs that store protien, amino acids, water and other nutrients. They can occupy upto 90% of the cell volume in plant cells. In animals cells, vacuoles are either very small or inside the vacuoles is called cell sap. It provides Turgidity and rigidity to the cell. 

-    Microbodies

            Microbodies are a kind of Organelles present in plants, animals and protozoa. 

They include Peroxisomes, Glycosomes, Glyoxysomes and Hydrogenosomes 

1- Peroxisomes:- Present in cytoplasm and mainly function in the detoxification of toxic substances

2- Glyoxysomes:-  Specialized peroxisomes in plants. 

3- Glycosomes:- Specialized peroxisomes in protists. 

4- Hydrogenosomes:-  Found in anaerobic eukaryotes. 

-    Centrosomes 

            They are only found in animal cells. They are not bounded by a membranes and consist of two centrioles. Centrosomes help in cell division. 

-   Nucleus

         It was first described by Robert brown in the year 1831. It is a large, spherical, centrally placed organelles found in the eukaryotic cells which is the central controlling unit of all the activities of a cell 

Structures of Nucleus

        It is surrounded by a double - membrane called nuclear envelope or nuclear membrane. Nuclear envelope contains many pores called nuclear pores. Nuclear pores allow transport of materials across nucleus, that is, form nucleus to cytoplasm and form cytoplasm to nucleus. Liquid substances present inside the nucleus is called nucleoplasm. It contain  nucleolus and chromatin material. 

       Nucleolus is the place where ribosomes are synthesized, it is rich in Protein  and RNA molecules. Chromatin material consists of thin, thread like, entangled structures composed of deoxy- ribonucleic acid (DNA) and proteins. At the time of cell division, chromatin condense to form rod shaped chromosomes.  

         Deoxy ribonucleic acid (DNA) stores information necessary for the  inheritance of characters from parents of the cell. Usually there is only one nucleus per cell, but there are no exceptions where more than one nucleus is present, for example  𝙥𝙖𝙧𝙖𝙢𝙚𝙘𝙞𝙪𝙢. Some mature cells even lack nucleus, for example, RBCs. 

Functions of Nucleus 

         Nucleus is the control centre of the cell, and controls the metabolic activities of the cell. Nucleus contains the genetic material, this stores information necessary for the inheritance of characters from parents to off spring. It also plays a major role in cellular reproduction, that is, the formation of new cells from the parents cell. 

   

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