* Introduction:-> Mitochondria are double-membrane-bound organelles found in almost all eukaryotes.
-> They are known as the "POWERHOUSE OF THE CELL" because they generate energy in the form of ATP through cellular respiration. -> It was discovered by Albert von Kölliker in 1857 and was named mitochondria by Carl Benda in 1898.
-> It can be clearly observed with an electron microscope by Palade in 1952.
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* Introduction:
-> Mitochondria are double-membrane-bound organelles found in almost all eukaryotes.
-> They are known as the "POWERHOUSE OF THE CELL" because they generate energy in the form of ATP through cellular respiration.
-> It was discovered by Albert von Kölliker in 1857 and was named mitochondria by Carl Benda in 1898.
-> It can be clearly observed with an electron microscope by Palade in 1952.
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* GENERAL FEATURES OF MITOCHONDRIA:
1) SHAPE: Oval or rod shape.
2) SIZE: About 0.5 to 1.0 micrometres in diameter and up to 10 µm long.
3) NUMBER PER CELL: Varies with energy need (they are few in number in resting cells, thousands in number in active cells (E.g., muscle and liver cells).
4) COLOUR: They are colourless or semi - transparent.
5) PRESENCE: Only present in eukaryotes and absent in prokaryotes.
* ORIGIN OF MITOCHONDRIA:
-> Mitochondria arise by growth and divisioning pre existing mitochondria.[ I.e., self-replication].
-> According to the endosymbiotic theory, mitochondria originate from free-living aerobic bacteria that enter the ancestral cells and form a symbiotic relationship.
* STRUCTURE OF MITOCHONDRIA:
-> Mitochondria are surrounded by two membranes and have four main parts :
1) OUTER MEMBRANE:
A) It is a smooth and continuous membrane.
B) It contains porin proteins, making it permeable to small molecules and ions.
C) It acts as a protective layer.
D) Also helps in the exchange of materials within the cytoplasm.
2) INNER MEMBRANE:
A) It is highly folded into finger-like projections, called Cristae it folds increases surface area for enzymes.
B) It contains enzymes for the electron transport chain (ETC) and ATP synthase.
C) The membrane is selectively permeable, allowing passage of specific ions and molecules.
3) INTERMEMBRANE SPACE:
A) It is a narrow space between the outer membrane and inner membrane.
B) It is rich in enzymes like Adenylate kinase that help transfer energy molecules ( ATP/ADP).
4) MATRIX:
A) It is the inner space enclosed by the inner membrane.
B) It consists of mitochondrial DNA ( mt DNA ) - circular , double standard , ribosomes (70 s type) for protein synthesis , enzymes for kerb's cycle ( TCA CYCLE) and t-RNA , ATP , ions and metabolites .
* FUNCTIONS OF MITOCHONDRIA:
1) ENERGY PRODUCTION( ATP Synthesis) :
-> Mitochondria perform aerobic respiration ( oxidation of glucose, fatty acids and amino acids).
-> The energy released is stored as ATP (Adenosine Triphosphate).
# MAIN STEPS FOR ENERGY PRODUCTION:
-> Glycolysis in cytoplasm to produce pyruvate.
-> Krebs cycle / TCA cycle in the matrix.
-> Electron transport chain in the inner membrane.
-> OXIDATIVE PHOSPHORYLATION - produces ATP by the ATP synthase enzyme.
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)
2) SELF REPLICATION:
-> Mitochondria contains its own DNA, RNA and ribosomes.
-> They can replicate independently like the cell of bacteria.
3) REGULATION OF CELLULAR MECHANISM:
-> It provides intermediates for fatty acids, amino acids and steroid synthesis.
4) CALCIUM IONS STORAGE:
-> Helps in storage and regulation of calcium ions within the cell.
5) ROLE IN APOPTOSIS: Programmed cell death)
-> It is a natural process.
-> Release of cytochrome c from mitochondria activates cascades leading to controlled cell death.
6) THERMOGENESIS: (Heat production)
-> In adipose tissue, especially in infants (newborns), mitochondria generate heat instead of ATP through uncoupling proteins.
7) ROLE IN AGEING AND DISEASE:
-> Damage to mitochondrial DNA can lead to ageing and neuromuscular diseases.
E.g: Parkinson's disease
Alzheimer's disease.
amazingly written
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