Question

make a report on any 4 cell organelles with their model,structure and functions. prepare a table and sudmit.​

Answer 1

Answer:

Single membrane-bound organelles: Vacuole, Lysosome, Golgi Apparatus, Endoplasmic Reticulum are single membrane-bound organelles present only in a eukaryotic cell. Double membrane-bound organelles: Nucleus, mitochondria and chloroplast are double membrane-bound organelles present only in a eukaryotic cell.

Answer 2

Answer:

1. Nucleus
2. Mitochondrion
3. Endoplasmic reticulum
4. Lysosomes

Explanation:

1. Nucleus:

They were firstly described by Robert brown. The name chromatin was given by Flemming in 1879.Chromatin are stained by basic dye. Nucleus is small spherical mass located somewhat in the center of the cell/cytoplasm. It has a delicate nuclear membrane inside which there is nucleoplasm somewhat like cytoplasm from whole cell. There is also a small section in nucleus called as nucleolus (just like a nucleus in entire cell). They participate in the process of protein synthesis. In the nucleoplasm there are chromatin fibers which get converted into chromosome in the period of cell division (there are total 46-23 pairs of chromosomes in nucleus of each cell of human). Nucleus controls all metabolic activities of the cell and the cell division. It is involved in the transmission of hereditary characters from parents to offspring.  

2. Mitochondria:        

                       

The mitochondria (singular-mitochondrion) are spherical, rod shaped or thread (mitos) like bodies.  These are minute double walled bags with their inner walls produced into fingerlike processes projecting inwards called cristae. On the surface of cristae there are bulged structures of F1-Fo particles. These particles are also known as Racker’s particles as they were discovered by him and Fernandez Moran. They have lollipop like shape. This particles are found all over the inner surface. The base of this particle is joint to the inner membrane and creates a pupping channel for H+ ions. The upper bulb like structure of this particle is a rich source of H + ions as it generates energy in proton motive force and supports energy bonding. The inner cavity is filled with proteinaceous gel like matrix containing (70s) ribosomes, phosphate granules and its own circular DNA and RNA. In these RNA and DNA the total number of Guanine and Cytosine is higher than Adenine and Thymine (in RNA uracil) in all nitrogen bases, hence the mitochondria and their DNA are stable. Therefore it can produce its own proteins. With the help of enzymes, mitochondria oxidise carbohydrates and fats in the cell. The energy released in this process is stored in the form of ATP (Adenosine Tri Phosphate).

3. Endoplasmic reticulum :

The endoplasmic reticulum is so fine in structure, its existence is revealed only through an electron microscope. It is an irregular network of double membranes distributed from nuclear membrane (nucleus) to cell (plasma) membrane over entire cytoplasm. It includes various parts such as tubules, vesicles, cisternae (folding). It forms supporting frame work of the cell and serves as a pathway for distribution of the materials from one part of the cell to other. It also carries the work of conduction of proteins. Toxins that have entered in our body through food, air, water are made water soluble by ER and then flushed out of the body. It appears rough when particles of ribosomes are attached to it, otherwise seems to be smooth without them. Hence it is names as SER and RER.

4. Lysosomes:

These are formed by the process of packaging of Golgi bodies. A lysosome is a membrane-bound cell organelle that contains digestive enzymes. They have acidic pH. than the cytoplasm and and the active condition is maintained by pumping of ions Lysosomes are involved with various cell processes. They break down excess or worn-out cell parts. They may be used to destroy invading viruses and bacteria. A lysosome has three main functions: the breakdown/digestion of macromolecules (carbohydrates, lipids, proteins, and nucleic acids), cell membrane repairs, and responses against foreign substances such as bacteria, viruses and other antigens. 50 years ago, Christian de Duve introduced the term “suicide bags” to describe lysosomes. When a cell becomes old or it’s damaged, lysosomes bursts and enzymes digest their own cells.

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