- Mito = Thread
- Chondria = Granules
Mitochondria is a double membrane bound cytoplasmic organelle.
You can read the single membrane bound organelles from here, SINGLE MEMBRANE BOUND ORGANELLES.
They are found in rod or oval shapes having diameter of 0.5 to 1 µ.
A single cell may contain 100 to 1000 of mitochondria based on its requirements.
These are the major site of aerobic respiration.
Also known as the “Power house” of the cell.
STRUCTURE OF MITOCHONDRIA
Outer mitochondrial membrane
- Forms a smooth envelope.
- Surrounds the contents of mitochondrion.
- Contains various enzymes (e.g., acetyl-coA synthetase, glycophosphatase, acetyltransferase).
- Most metabolites can move freely through it.
Inner mitochondrial membrane
- Having a series of inward projections (shelf-like folds) which are known as cristae (means ridges).
- These tortuous folds of cristae give a large surface area for chemical reactions (process of oxidative phosphorylation that produces most of the ATP of cell).
- The constituents of electron transport chain are also located here.
- It is a central fluid filled cavity which is enclosed by the inner mitochondrial membrane.
- Contains enzymes of TCA cycle, β-oxidation of fatty acids and some other catalytic enzymes.
- There are Ribosomes present here which synthesize the proteins required for mitochondrial functions.
FUNCTIONS OF MITOCHONDRIA
- Regulates the cellular metabolic activities.
- Mitochondria supports the growth of cells and its multiplication.
- It detoxifies the toxic substances like ammonia in the liver cells.
- Plays an important and early role in apoptosis (Genetically programmed cell death).
- Helps to build certain blood components.
- Plays role in production of various hormones like oestrogen and testosterone.
- Calcium ion concentration is maintained within the cell with the help of mitochondria.
- Mitochondria is also involved in cell growth, cellular differentiation, cell aging, cell signaling etc.
SOME INTERESTING FACTS ABOUT MITOCHONDRIA
- Mitochondria can self-replicate just like peroxisomes when there is increased demand of energy or during cell divisions.
- Mitochondria have their own circular DNA copies with 37 genes. These genes control the synthesis of 2 ribosomal RNAs, 22 transfer RNAs and 13 proteins to build components of mitochondria.
- We inherit mitochondrial genes only from our mother (unlike each somatic cell genes are from both of our parents). So, mitochondrial DNA can be used to determine whether two or more persons are related by their maternal side of family.
Read the Non membrane bound cellular organelles here… CELLULAR ORGANELLES: STRUCTURE AND FUNCTIONS.
The single membrane bound organelle is available here… MEMBRANE BOUND CELLULAR ORGANELLES.