Mitochondria
They are also called as chondriosome, sarcosome, bioplast, plastochondria:They are power house of cell, largest organelle in animal cell and 2nd largest
organelle in plant cell.
These are double walled, DNA containing, self replicating, semiautonomous, organelle found only in eukaryotic aerobic cells (except mature RBC), first observed in insect striated muscles as granular structure by Kolliker (1850). He called these granules of striated muscles as sarcosomes. Altman (1890) studied them in detail and called them as bioplasts.
He considered them as symbionts
comparable to bacteria. Flemming called them file and term ‘mitochondria’ wasused by Benda (1897) who stained them with Janus green B (a vital stain); size
1 = 10µ × 0.2 – 1 µ; Number 1 per cell in Microsterias and Trypanosoma; 50,000 in
Choas chaos and 30,000 to 3 lakhs in oocytes of sea urchin.
A mitochondrion has two chambers and two membranes. Inner membrane is folded
to form cristae which bear oxysomes (F0-F1 particles, elementary particles, ATPase
particles. (Fernandez and M oran particles). Oxysomes are 104 to 105 in number, called functional unit of mitochondria, discovered by Fernandez-Moran (1961).
Inner chamber has a double stranded, naked circular 5 µ long prokaryotic DNA with high G-C ratio, 70S ribosomes, RNA and 70 types of enzymes. 70% of total enzymes of cell are found in mitochondria.
This DNA is 1% of total DNA of cell and discovered by Nass (1966). Kreb’s cycle and oxidative phosphorylation occur here. Mitochondria are called cell within cell.
Comments
Post a Comment