Mitochondria are organelles that generate ATP through aerobic respiration in eukaryotic cells. They have an outer and inner membrane that form compartments and invaginations called cristae where the machinery for ATP production is located. Mitochondria play key roles in energy production, synthesis of molecules, calcium ion transport, and regulating cell death. They have their own DNA, ribosomes, and mechanisms for expressing genes to produce some proteins required for their functions.

1. MITOCHONDRIA

2. • Anaerobes —organisms that capture and utilize energy using oxygen‐independent
(anaerobic) metabolism
• Aerobes ----organisms that incorporated O 2 into their metabolism could completely oxidize
such compounds to CO 2 and H 2 O and, in the process, extract a much larger percentage of
their energy content.
In eukaryotes, the utilization of oxygen as a means of energy extraction takes place in a
specialized organelle, the mitochondrion

3. ROLES OF MITOCHONDRIA
1. Generation of ATP: 2. Site of synthesis of various substances
• Primary role
• Used to run most of the
cellular activities
Eg: amino acids, the
heme group
3. Uptake of and release of calcium ions 4. The process of cell death is also regulated to a large
extend by the events that occur in mitochondria
when Ca 2+
concentrations rise to
abnormally high levels in
the cytosol, a Ca 2+
transporter in the inner
mitochondrial membrane
takes up some of the
excess Ca 2+ ions

4. • Bean-shaped
organelle
• Length range: 1 to 4
micrometers
• Highly branched,
interconnected
tubular network

5. Mitochondrial
membrane
Outer
membrane
Inner
membrane
Double
membrane
Inner
mitochondrial
membrane
Inner boundary
membrane
Cristae
• rich in the proteins
responsible for the import
of mitochondrial proteins.
• Series of invaginated
membranous sheets.
• Contains a large
amount of membrane
surface which houses
the machinery needed
for aerobic respiration
and ATP formation.
**The inner boundary membrane and internal cristae membranes are joined to one another by narrow tubular
connections called ‘cristae junctions’

6. Membranes of
mitochondria divide
the organelle into 2
aqueous compartments
Matrix Intermembrane space
(within the interior of
the mitochondria)
(between the outer and inner
membrane)
• Proteins of intermembrane
space are best known for
their role in initiating cell
suicide

7. MITOCHONDRIAL MATRIX
• It has a gel-like consistency due to the presence of a high concentration of water-soluble proteins.
• It contains ribosomes(considerably smaller in size as compared to those in the cytosol).
• It contains several molecules of DNA, which are circular in higher plants and animals.
• Mitochondria has its genetic material and machinery to manufacture its RNAs and proteins.
• The non-chromosomal DNA encodes a small number of mitochondrial peptides that are tightly integrated into
the inner mitochondrial membrane
• Mitochondria are also partly independent or semi-autonomous as they can manufacture some of the proteins
required for their effective functioning with the help of their DNA, RNAs, enzymes, and ribosomes & and
obtain others from the cytoplasm.
• Human mitochondrial DNA encodes 2 rRNAs and 22 tRNAs, used in the synthesis of protein inside the
mitochondria.
• RNA polymerase, in mitochondria, is a single subunit enzyme, similar to bacterial viruses.