A well defined presentation on MITOCHONDRIA with all the necessary information including Marker Enzyme as well as the cycles of mithochondria for Undergraduate and post graduate students.

1. MITOCHONDRIA
(powerhouse of the Cell’s)

2. Mitochondria are a double membrane-bound organelle found in most eukaryotic organisms. They
are found inside the cytoplasm and essentially function as the cell’s “digestive system.”
They play a major role in breaking down nutrients and generating energy-rich molecules for the
cell. Many of the biochemical reactions involved in cellular respiration take place within the
mitochondria.

3. STRUCTURE OF MITOCHONDRIA
Outer Membrane
Inner Membrane
Inter membrane space
Matrix
size ranges from 0.5 to 1.0 micrometre in diameter.
Porins at surface

4. OUTER MEMBRANE
• The outer membrane of mitochondria is primarily composed of phospholipids, with small amounts of
cholesterol and proteins. The specific phospholipids present in the outer membrane determine its
fluidity and contribute to its role in maintaining the structure and function of the organelle.
• These phospholipids play important roles in cell signaling, energy metabolism, and other cellular
processes.
INNER MEMBRANE
• The inner membrane of mitochondria is composed primarily of phospholipids, which are molecules with
two tails and a head group. These tails form a hydrophobic barrier that prevents large molecules from
crossing the membrane, while the head groups can interact with water on the outer side of the
membrane.
• The inner membrane contains enzymes, electron transport chains, and metabolic pathways involved in
energy production.
• The composition of the inner membrane is crucial for mitochondrial function and plays a significant role in
cellular metabolism.

5. INTER MEMBRANE SPACE (IMS)
• The composition of the IMS includes phospholipids, which provide an outer layer that separates
the matrix from the cytosol, as well as positively charged proteins and small molecules such as
lipids, vitamins, and cofactors.
• The IMS is responsible for transporting a variety of molecules between the mitochondrial matrix
and the cytosol, including Ca2+, Pi, lipids, nutrients, toxins, and wastes.
MATRIX
• The mitochondrial matrix contains the mitochondrial DNA, ribosomes, soluble enzymes, small
organic molecules, nucleotide cofactors, and inorganic ions.
• The protein matrix comprises around 15% of the total mass of the mitochondrial matrix, and it
plays a crucial role in maintaining the structure and function of the organelle.
• The enzymes found in the matrix include those involved in the citric acid cycle, which produces
ATP and FAD.

6. GENETIC MAKEUP OF MITOCHONDRIA
• Mitochondria have their own genetic material, called mitochondrial DNA (mtDNA), which is separate from
the DNA in the cell's nucleus. The human mitochondrial genome is a circular double-stranded DNA molecule
of about 16,500 base pairs, which contains 37 genes that are essential for normal mitochondrial function.
• Mitochondrial DNA is inherited only from the mother's ovum, and not from the father's sperm.
• Mitochondrial DNA mutations can lead to functional problems, which may be manifested as muscle
disorders.
PROTEIN MAKEUP OF MITOCHONDRIA
• The protein makeup of mitochondria is complex and involves hundreds of different proteins, many of which
are involved in the electron transport chain, the citric acid cycle, and other metabolic pathways.
• They have a double membrane structure and contain more than 151 different polypeptides, with a very high
protein-to-phospholipid ratio (more than 3:1 by weight, which is about 1 protein for 15 phospholipids).
• Some of the key proteins found in mitochondria include NADH dehydrogenase, cytochrome c oxidase, and
succinate dehydrogenase.

7.  Unique mitochondrial protein with dual
origin is cytochrome c oxidase, It plays a
crucial role in cellular respiration.
 Cytochrome c oxidase is a complex
protein that is responsible for the final
electron acceptor in the electron
transport chain, a series of protein
complexes that are embedded in the
inner membrane of the mitochondrion.
 Cytochrome c oxidase is a complex
enzyme made up of multiple subunits,
including heme, copper, and iron ions. It
is also involved in the production of
reactive oxygen species, which can have
both beneficial and harmful effects on
cells.
It is believed to have evolved from an ancestral
complex of three heme-containing subunits,
ccd1, ccd2, and ccd3, which were fused together
and transported into the mitochondrial matrix.
Then the two heme groups in the complex were oriented
in opposite directions, and over time, the orientation
was fixed in only one direction, leading to the formation
of the single heme group characteristic.

8. Regulates the metabolic activity of the cell.
Promotes the growth of new cells and cell multiplication.
Helps in detoxifying ammonia in the liver cells.
Plays an important role in apoptosis or programmed cell death.
Responsible for building certain parts of the blood and various hormones like testosterone and
oestrogen.
Helps in maintaining an adequate concentration of calcium ions within the compartments of the
cell.
It is also involved in various cellular activities like cellular differentiation, cell signalling, cell
senescence, controlling the cell cycle and also in cell growth.
FUNCTIONS

9. o Oxidative phosphorylation, which occurs in the inner
membrane of the mitochondria . The process
involves a series of chemical reactions that convert
glucose and oxygen into ATP, carbon dioxide, and
water.
o The electron transport chain (ETC) is a key
component of this process, which pumps positively-
charged protons that drive ATP production
throughout the mitochondria's inner membrane.
o The ATP synthase enzyme is also present in the inner
mitochondrial membrane, which is responsible for
synthesizing ATP from ADP and inorganic phosphate.
.
ATP PRODUCTION

10. The citric acid cycle —also known as
the Krebs cycle, Krebs cycle or the
TCA cycle —is a series of chemical
reactions to release stored
energy through the oxidation of
acetyl-CoA derived from
carbohydrates, fats, and
proteins. The Krebs cycle
is used by organisms that
respire to generate energy,
either by anaerobic
respiration or aerobic
respiration . In addition, the
cycle provides precursors of
certain amino acids, as well as
the reducing agent NADH, that are
used in numerous other reactions.
Its central importance to many biochemical
pathways suggests that it was one
of the earliest components
of metabolism. Even though it is
branded as a 'cycle', it is not
necessary for metabolites to
follow only one specific route,
At least three alternative
segments of the citric acid
cycle have been recognized.
It is a series of chemical
reactions that convert two
molecules of pyruvic acid into two
molecules of acetyl-CoA, which can
then be used to generate ATP and NADH
through cellular respiration.

11. CALCIUM REGULATION BY MITOCHONDRIA
o Mitochondria play a crucial role in calcium
regulation. They control the uptake and release of
calcium ions through channels and transporters,
such as the mitochondrial calcium uniporter (MCU),
and influence the concentration of calcium in both
mitochondria and cytoplasm, thereby regulating
cellular calcium homeostasis.
o Calcium crosstalk exists in the domain created
between the endoplasmic reticulum and
mitochondria, which is known as the mitochondria-
associated membrane (MAM), and controls cellular
homeostasis.
o Alterations in calcium homeostasis may also support
resistance to apoptosis, which is a serious problem
facing current chemotherapeutic treatments.

12. o Marker enzymes are enzymes that are used to identify a specific cell type, cell organelle, or cell
component.
o They are also blood tests that measure the levels of specific enzymes in the body.
o Marker enzymes can help diagnose diseases or defects that affect how enzymes work and in field such as
medical diagnosis and research. They can be identified by specific antibodies or probes, and their
expression patterns can provide valuable information.
o Citrate synthase and succinate dehydrogenase are commonly used as marker enzymes for mitochondria.
o Citrate synthase is used as a quantitative enzyme marker for the presence of intact mitochondria. Maximal
activity of citrate synthase indicates the mitochondrial content of skeletal muscle.
o Succinate dehydrogenase is an essential mitochondrial marker enzyme that connects the oxidative
phosphorylation and the electron transport chain. It provides a variety of the electrons needed in the
respiratory chain process taking place in the mitochondria.
MARKER ENZYME

13. Mitochondria are organelles that are responsible for producing energy within your body. Mitochondrial diseases are a
group of genetic conditions that affect how mitochondria in your cells produce energy. If you have a mitochondrial
disease, your cells aren’t able to produce enough energy.
Mitochondria play a key role in:
 Muscle contraction, including important muscles like the heart, Muscle tone.
 Brain function and Cognitive development.
 Energy that nerves need to pass information.
 Cellular repair and healing by coordinating the death of weak cells.
 Hormone signaling.
 Aging & longevity, protecting the DNA integrity.
They play a pivotal role in cell life and cell death. They are engaged in the pathogenesis of human diseases and aging
directly or indirectly through a broad range of signaling pathways. Mitochondria help decide which cells are destroyed,
and are thought to play a role in certain diseases, such as cancer.
As we age, mitochondria undergo changes that lead to a decline in their function. These changes include a decrease in
mitochondrial DNA volume, integrity, and functionality due to the accumulation of mutations and oxidative damage
induced by reactive oxygen species (ROS).
DISORDERS AND MITOCHONDRIA