Mitochondria

MITOCHONDRIA

👉 Number of mitochondria depends upon physiological activity of cell.

👉One in Microasterias,Chlorella fusca(alga).

👉 All the mitochondria present in a cell are collectively called chondriome.

👉 Usually plant cells have fewer mitochondria as compared to animal cell.

👉 In higher animals maximum mitochondria are found in flight muscles of birds.

👉 Mitochondria are differ in size and shape and can make its shape sausage or cylindrical.

STRUCTURE:-

👉 Mitochondria unless specifically stained are not easily visible under the microscope. Mitochondria are stained by Janus green B.

👉 Mitochondria is covered by double unit membrane. Outer membrane has more phospholipids (Phosphatidyl choline) and cholesterol as compared to inner membrane. Phospholipid in inner membrane is mainly diphosphatidyl glycerol and inner membrane have more protein.

👉 The outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments, i.e., the outer compartment and the inner compartment. The inner compartment is called the matrix. The outer membrane forms the continuous limiting boundary of the organelle. The two membranes have their own specific enzymes associated with the mitochondrial function.

Specific enzymes associated with the mitochondrial function.

👉 Both membrane are separated by a space called perimitochondrial (intermembrane) space.

👉 Inner membrane is folded into a number of finger like cristae.

👉 In metabolically active mitochondria number of cristae is higher.

👉 Many electron carrier cytochromes are arranged in a definite sequence in inner membrane of Mitochondria, which forms Electron transport system (ETS).

👉 Inner membrane is studded with pin head particles called oxysomes or elementary particles or Fo - F1 particles. These particles first described by Fernandez Moran.

👉 Head of oxysomes or F1 is concerned with oxidative phosphorylation (formation of ATP by energy of oxidation).

👉 Mitochondrial matrix have enzyme for kreb's cycle (Aerobic respiration). Beside these enzymes Matrix have a complete protein synthesis apparatus (Ribosome- (70s), DNA, few RNA's and enzymes) so mitochondria called as semi autonomous cell organelle.

👉 Single, double stranded and circular naked DNA present in mitochondria matrix.

👉 Mitochondria DNA is 1% of total DNA in a Cell. It is rich in G-C content.

👉Mitochondrial DNA can code the synthesis of some types of proteins. Rest of the proteins and enzymes of mitochondria are synthesized under the control of nuclear genes.

👉 Enzymes for replication and transcription of DNA like DNA polymerase and RNA- polymerase are found in mitochondrial matrix.