Mitochondria

Double membrane enclosed oragnelle of diameter 0.5 to 10 micrometres which is mainly found in eukaryotic cells. mitochondria is inherited only from mother. It is also known as the power house of the cell or energy factories because they are resposible for making the energy currency which Adenosine Triphosphate(ATP). Some multicellular organisms lacks mitochondria like mature mammalian red blood cells.

It is semi-autonoumous organalle because it has its:

- OwnCircular DNA

-and own Ribosome

Structure:

It consists

1.      1Outer membrane
2.       Inner membrane
3.       Cristae
4.       Inter-membrane space
5.       Matrix

1). Outer membrane:

Outer membrane of mitochondria is completely surrounded by the inner memmbrane with the small intermembrane space in between. It consists of 50% phospholipids by weight and also many enzymes. It is porous in nature.

2). Inner membrane:

The inner membrane of mitochondria gets folded over sevral times and formes a layered structure which is known as Critae. Containing high amount of protein than phospholipids. It is not porous in nature because it do not contains porins like outer membrane.
The machinery which is responsible for ATP formation and It is the site of electron transport chain which is and important step for aerobic respiration that is present in it.
It is the site of electron transport chain

3). Cristae :

The name cristae dervied from latin word  for crest it is responsible for giving the wrinkled shaped, providing the large surface area for ATP synthesis.

4). Inter-membrane space:

The compartment present between the outer membrane and iner membrane of mitochondria and  a protein called cytochrom c found in it and this protein is required for suicide of cell.

5). Matrix

The space in inner membrane gel like consistence due to high concentration of water soluble protein known as matrix it conatains mitochondrial’s dna, soluble enzymes, ribosomes, small organic molecules, inorganic ions and nucleotide cofactors.

Function of mitochondria:

1.       1. The primary function of mitochondria to produce energy currency of the cell is ATP by converting the organic materials into cellular energy.
2.       Heat production
In certain condition the re-entry of protons in the matrix of mitochondria without contribution of ATP synthesis. This whole process is known as proton leak and it happens due to the facilitated diffusion of protons into the matrix and hence heat released.
3.       Storage of calcium
Uptake and release of calcium ions.
4.       It the site of synthesis of certain amino acid and heme group.
5.       Helps in regulation of cell death, which is apoptosis.
6.       Control of the cell cycle and cell growth.
7.       Cell signalling
8.       Steroid synthesis.
9.       Immue signaling.
10.   Regulation of membrane potential