Category: Biology Second Paper

1. Membrane: Each mitochondrion is covered by a bilayered membrane. Outer cover and inner cover. The outer layer is called the outer layer and the inner layer is called the inner layer. The outer coat is smooth and the inner coat is rough. Each coat is 40–60 Å thick. The space between the two membranes is called the perimitochondrial space. The distance of perimitochondrial space is 6-8 nm. It is composed of lipoproteins. It gives the mitochondria specific shape and protects them from external injury.
2. Chambers: Mitochondria have two types of chambers. Outer chamber and inner chamber. The compartment between the outer and inner envelope is called the outer compartment and the compartment between the inner envelope is called the endocompartment (70 Å wide). It is filled with various chemicals.
3. Matrix: The jelly-like substance inside the cell is called matrix. It is dense, homogenous and full of enzymes and co-enzymes.
4. CRISTIE: The inner membrane of the mitochondria folds inwards to form a number of finger-like extensions. It’s called Christy. The space between each cristae is called the intercristi space.
5. Oxysome or F1 Cells: Mitochondria have numerous fine granules like tennis bats on the inner envelope. These are called oxisomes or F1 cells. It consists of head, stem and base. There are two types of oxisomes. Sabrintak and Abrintak. The oxisomes which have a stalk are called stalked oxisomes and the oxisomes which do not have a stalk are called unstalked oxisomes. It has ATP-ase enzyme in its head.
6. ETS: Electron Transport System is abbreviated as ETS. It is called ETC (Electron Transport Chain). Christy has ETS on him. It transfers electrons from one place to another.
7. ATP-Synthases: All substances that synthesize ATP are called ATP-Synthases. Christy has spherical or oval ATP-synthases. It produces ATP.

There are three theories about the origin of mitochondria.
1. De novo origin: According to this theory, amino acids and lipids combine to form mitochondria. This doctrine is not accepted at present.
2. Cell membrane or endoplasmic origin: According to scientist Morison (1966), vesicles are formed from endoplasmic reticulum or cell membrane and mitochondria are formed from vesicles. This doctrine is now defunct.
3. Mitochondrial origin: According to this theory, during cell division, old mitochondria divide to form new mitochondria. The new mitochondria quickly change shape and move to other parts of the cell. It grows rapidly and divides to increase the number of cells to meet more energy.

Each cell has an average of 300-400 mitochondria. Advanced plant cells contain 100-3000 mitochondria. Liver and kidney cells contain 1000 or more mitochondria. Human sperm has 20 mitochondria. A sea urchin egg has 140,000 mitochondria, an amphibian egg has 300,000, and an Amoeba has 500,000. Mammalian red blood cells do not contain mitochondria.

All true cells contain mitochondria. Stem cells, progenitor cells, and red blood cells do not contain mitochondria.

 In shape it is round, rod, oval, star or coil shape.

 Mitochondria make up 20% of cell volume. Mitochondria are typically 3-40 microns in length and 0.2-2.0 microns in diameter. Rod mitochondria are 9 microns in length and 0.5 microns in width. Circular mitochondria are 40-70 microns in length. Circular mitochondria are 0.2-2.0 microns in diameter.

In 1850, the Swiss scientist A.V. Kolliker noticed tiny organelles in insect muscle cells and named them sarcosomes. He is called the discoverer of mitochondria. In 1882 W. Fleming observed filamentous mitochondria and named them Fila. In 1890, Altman named it Bioplast. Mitochondria was named by Carl Benda in 1898. In 1904, Frederick Mavis was the first to observe mitochondria in the plant cell Nymphaea alba. In 1957 scientist Philip Siekevitz coined the term Power House of the cell. Modern scientists call mitochondria semi-autonomous cells. They also called it electrosome. Mitochondria are also known as chondriosomes and plasmosomes. Mitochondria of birds’ flight muscles are called sarcosomes.

The word Mitochondria is formed from the Greek word mitos meaning thread and chondrion meaning grain. Mitochondria means filamentous grains. The energy producing organelles located in the cytoplasm are called mitochondria. It is called Power House as it provides the necessary energy for cells.

1. Formation of intracellular skeleton: Endoplasmic reticulum extends like a net inside the cell and forms the intracellular skeleton. It provides cell strength.
2. Structure of the body: Endoplasmic reticulum acts as the structure of protoplasm.
3. Speed ​​of reaction: It increases the speed of chemical reaction. It increases biochemical activity in cells.
4. Substance transport: Endoplasmic reticulum forms the intracellular transport system. It acts as a transport pathway for various substances. It plays a major role in the transport of proteins produced in ribosomes.
5. Hydroxylating: Different types of drugs and toxic substances enter the body. The endoplasmic reticulum inactivates drugs and toxins in the hydroxylating process. As a result, the body gets rid of toxins.
6. Muscle contraction-dilation: It helps in muscle contraction-dilation.
7. Cell wall formation: It makes cellulose. Cellulose participates in making cell walls.
8. Chemical production: It produces lipids, hormones, phospholipids, steroids, glycoproteins, glycogen, vitamins and insulin.
9. Organelle formation: Endoplasmic reticulum participates in the formation of various organelles of the cell.
10. Protein synthesis: It synthesizes proteins. Proteins make up the body of organisms.
11. Cell distribution: The endoplasmic reticulum holds the cell membrane in place and distributes it uniformly.
12. As a container: It acts as a container for ribosomes and glyoxysomes.
13. Nuclear membrane formation: It participates in nuclear membrane formation in telophase.
14. Glucose production: Glucose is produced from glycogen in the process of glycogenolysis.
15. Formation of Spherosomes: Spherosomes are formed from smooth endoplasmic reticulum.
16. As a carrier: It acts as a carrier of proteins and lipids.
17. Neutralization: It neutralizes various toxic substances entering the cells.

The main chemical components of endoplasmic reticulum are proteins and lipids. It contains protein 60-70% and lipid 30-40%. Asymmetric lattice contains ATP and glyoxysomes. Besides, it contains 15 types of enzymes and co-enzymes. Enzymes are – glucose 6 phosphate, NADH diaphorase, active ATP-ase, glycosyl transferase, NADH cytochrome reductase, stearase, esterase, nucleotide diphosphatase, peptidase, fatty acyl CoA dehydrogenase etc.

There are three types of structure of endoplasmic reticulum. These are-
1. Lamellar or Cisternae: Endoplasmic reticulum that is long, cylindrical, unbranched and compressed is called cisternae. Their diameter is 40-50 millimicrons. Cisternae contain a glycoprotein called ribophorin. The cisternae are connected to each other with the help of ribophorin.
2. Vasicle: The endoplasmic reticulum that looks round or oval or blistered and surrounded by a membrane is called a vesicle. The vesicles are called microsomes. Their diameter is 25-50 mm. Vesicles are abundant in protein-synthesizing pancreatic cells.
3. Tubules: The endoplasmic reticulum which is long, cylindrical and branched is called tubules. Their diameter is 50-190 millimicrons. It stays connected. They have no ribosomes.

1. Smooth endoplasmic reticulum-SER: The endoplasmic reticulum that does not have ribosomes is called smooth endoplasmic reticulum or SER. It synthesizes lipids. It releases calcium during muscle contraction. Smooth endoplasmic reticulum is abundant in adipose cells, testes, adrenal cortex cells, muscle cells and liver cells.
2. Rough endoplasmic reticulum-RER: The endoplasmic reticulum that has ribosomes is called rough endoplasmic reticulum or RER. It synthesizes proteins. It stores calcium during muscle contraction. Rough endoplasmic reticulum contains tiny glyoxysome particles. These tiny glyoxysome particles are called microsomes. Pancreatic cells, liver cells, plasma cells and goblet cells have rough endoplasmic reticulum.