Mitochondria are double-membrane bound organelles found in the cytoplasm of eukaryotic cells. They are often described as the "powerhouses" of cells since their main function is to produce ATP through oxidative phosphorylation. Mitochondria contain their own DNA and ribosomes. They have an outer and inner membrane that create compartments like the intermembrane space. The inner membrane forms folds called cristae that contain protein complexes for ATP synthesis. In addition to producing energy, mitochondria also perform other functions like thermogenesis, apoptosis, and hormone synthesis.

1. Mitochondria
By
Mrs Sanchita Choubey
(M.Sc., PGDCR, Pursuing Ph. D)
Assistant Professor of Microbiology
Dr. D Y Patil Arts Commerce and Science College Pimpri, Pune

2. INTRODUCTION
 The mitochondrion (plural mitochond
ria) .[greek];
 It is a double membrane-
bound organelle found eukaryotic
cells.
 mito= thread
chondrion = granule like
 Found in cytoplasm of the cell.
 Power house of cell.
 First observed by Richard Altman
(1894).
 Term mitochondria was coined by
Carl Benda (1898).

3. SIZE: Mitochondria range from 0.5 to 1.0 μm in diameter.
SHAPE: normally Sausage shaped,
 In fibroblasts-elongated and thread like
NUMBER: Depends on type size and functional state of
cell.
Eg: An average liver cells contain around 1500
mitochondria.
LOCATION: Cells with high enrgy requirements;
Eg:Sperm tail, Muscle, Flagella

4. 1. Outer Membrane
2. Intermembrane Space
3. Inner Membrane
4. Cristae
5. Matrix

6. OUTER MEMBRANE
⦿ Simple phospholipid bilayer.
⦿ It encloses the mitochondrion.
⦿ Containing protein structures called porins.
⦿ Ions, nutrient molecules,ATP,ADP, etc. can pass through the outer membrane
with ease.
INNER MEMBRANE
⦿ Is freely permeable only to oxygen, carbon dioxide, and water.
⦿ Contains complexes of the ETC, theATPsynthase complex, and transport
proteins.
⦿ Presence of sophisticated ion transporters exist.
⦿ Several antiport systems exist, allowing exchange of anions between
the cytosol and the mitochondrial matrix.
⦿ It is devoid of cholesterol and rich in phospholipid & cardiolipin.

7. Intermembrane space
Matrix

8. the space between inner
membrane and outer
membrane {O cavity}
 It has high proton concentration.
 The space between inner and outer memebrane is
approx 70 angstrom.
 Conc is same as that of the cytosol.
 CRISTAE
Are folds of inner mitochondrial membrane.
 Stalked particlesor inner membrane spheres: cristae
is covered with this inner membrane spheres called
stalked particles or knobs or heads.
 They contain protein called F1 portion &F0 portion.
For ATP synthesis and ATO oxidation.

9. MITOCHONDRIAL MATRIX:
Gel like consistency
Dense ,homogenous
2/3rd of total protein of mitochondria
 Mitochondria have: - enzymes
-ribosomes
-DNA
-mRNA
-granules
-fibrils
-tubules.
Major enzymes include enzymes involved in:
-Synthesis of nucleic acid and proteins
-Fatty acid oxidation
-TCACYCLE (except succinate dehydrogenase)

10. MITOCHONDRIAL DNA (mt DNA):
Double stranded, covalently closed,
circular molecule.
Occurs in multiple copies.
Most usually remains attached to inner
mitochondrial membrane.
Stores biological info required for growth
and multiplication of mitochondria.
Can undergo replication and duplication.
 Human mt DNA 2 rRNA
22 tRNA
Not absolutely autonomous depends on
nuclear DNA.[partially autonomous]

11. FUNCTIONS OF MITOCHONDRIA:
Energy transducer of the cell- synthesis of ATP
Kreb’s cycle in matrix
ETC system
Phosphorylating system-ATPase
Extra mitochondrial inheritance:
mtDNAcontains plasma genes (extra chromosomal genes)
Transmitted from mother to the offspring
Synthesis of mtDNA, RNA, protein.
 Bring about gene expression through gene duplication
transcription and translation.
Synthesis 13 different polypeptides in human.

12. Outer membrane
Site of several metabolic reactions
Oxidation of epinephrine
Degradation of tryptophan
Elongation of fattyacid
Inner membrane : oxidative phosphorylation
 Matrix
Kreb’s cycle
Beta oxidation
Detoxification of ammonia in urea cycle
Storage of calcium ions

13. OTHER FUNCTIONS:
 production of heat ( non shivering thermogenesis).
[ The unharnessed potential energy of proton-electrochemical
gradient produced during ETC is released as heat.]
Role in apoptosis ( programmed cell death).
Synthesis of estrogen and testosterone.
Role in neurotransmitter metabolism.
Role on cholesterol metabolism.