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MITOCHONDRIA STRUCTURE
By
Prof. DR. IR. CHANIF MAHDI, MS.
DEPARTEMENT OF CHEMISTRY
BRAWIJAYA UNIVERSITY
Diagrame of the mitochondria structure
Mitochondria
Mitochondria contain two membranes,
separated by space. Inside the space enclosed
by inner membrane is the matrix.
These appears moderatly dense and one may
find strands of DNA, Ribosome, or small granula
in the matrix.
The above diagrame shows the diagram of the
mitochondrial membranes and the enclosed
compartement.
Contd
Mitochondria is the Power of house of the cell.
How are mitochondria organized to be power house.
The food we eat is oxidized to produce high energy
electrons that converted to store energy. This energy is
stored in high energy phosphat bond in a molecule
called Adenosine Triphosphate (ATP).
ATP is converted from Adenosine Diphosphat by adding
the phophat group with high energy bond.
Various reaction in the cells can be either use energy (
where by the ATP is converted back to ADP( releasing
the high energy bond).
REAKSI PEMBENTUKAN ENERGI
C6 (H2O)6 + H2O
O2 + 4H+ + 4 e
NADP+ + 2 H+ + 2 e
Energi + ADP + H3 PO4
NADPH + H+ + Energi
ATP
Why are mitochondria important
The food we eat must first be converted to basic
chemicals that the cell can use. Some of the
best energy supplaying foods contain sugar or
carbohydrates.
The sugars are broken down by enzymes that
split them into into simplest form sugar which
called glucose . Then glucose enters the cell by
special molecules in the membrane called “
Glucose transporter”.
Contd
Once inside the cell, glucose is broken down to
make ATP in two pathways.
The first pathways requires no oxygen and is
called “ anaerobic metabolism” this pathway is
called glycolysis and it occur in the cytoplasm,
outside of mitochondria.
During glycolysis, glucose is broken down into
pyruvate.
Contd
Each reaction is designed to produce some
hydogen ions (electron) that can be used to
make energy packet ( ATP ). However, only 4
ATP molecules can be made by one molecule of
glucose run through this pathway.
That is why mitochondria and oxygen are so
important.We need to continou the breakdown
with the Krebs cycle inside the mitochondria in
orde to enough ATP to run all the cell function.
Figure 2. Mitochondria as power house of the cell
Figure : Glycolysis diagrame
Figure : Anaerob and aerob meabolism
Figure 2. Information
Pyruvat is carried into the mitochondria and it converted
into Acetyl Coa which enter the Krebs cycle. This first
reaction produce carbon dioxide, because it involves the
removal of one carbon from pyruv, atc.
How does the Krebs Cycles work.
The whole idea behind respiration in the mitochondria is
to use the Krebs ( also called the Citric acid Cycle ) to
get many electron ( in the form of hydrogen ions ), are
then used to drive pumps that produce ATP. The energy
carried by ATP is than used for all kind of cellular
function, like movement, transport, entry and exit
products, devision, etc.
Contd
First, you need pyruvate, which is made by
glycolysis from glucose. Next you need some
carrier molecule for the electrons. There are two
types of these : one called Nicotinamide Adenin
Dinucleotide ( NAD+ ), and the other is called
Flavin Adenin Dinucleotid ( FAD+ ), The third
molecule, of course is oxygen.
Pyruvat is a 3 carbon molecule. After inter the
mitochondria, it is broken down to a 2 carbon
molecule by special enzyme. This release
contd
molecule are called acetyl Coa and it enters the Krebs
Cycle by joining to 4 carbon molecule called Citric acid (
2 carbon + 4 carbon = 6 carbon). That is where the citric
acid cycle got it name. ( from the first reaction, that make
citric acid).
Citric acid is then broken down, and modified in a
stepwise fashion ( See text for details), and as the
happens, hidrogen ions and carbon molecules are
released.
The carbon molecules are used to make more carbon
dioxide and the hydrogen ions are picked up by NAD
and FAD.
Contd
Eventually the process produces the 4 carbon
oxalo acetat again. The reason, the process
called cycle, is because its ends up always
where it started, with oxalo acetat available to
combine with more acetyl Coa.
Oxydative Phosphorilation
First some basic difinition. When you take hydrogen ion
or electron away from molecule, you “ oxydaze” that
molecule. When you give hydrogen ion or electron to a
molecule, you “ reduce” that molecule.
So, oxidative phosphorilation ( very simply) mean, the
process that couples the removal of hydrogen ion from
molecule and giving phosphat molecule to another
molecule. How does this apply to mitochondria?
Contd
As the Krebs cycle runs, hydrogen ion ( or electron ), are
donated to the two carrier molecules in the 4 of the
steps. They are picked up by either NAD or FAD, and
this molecules became NADH and FADH ( becauce they
now are carrying a hydrogen ion). The following
diagrame shows what heppens next ( Figure 3).
Figure 3.
More information Figure 3
The electron are carried chemically to the respiratory or electron
transport chain found in the mitochondria crestae ( see diagram
above and bellow).
The NADH and FADH essentially serve as Ferry in the lateral plane
of the membrane diffusing from one complex to the next.
At each site is the hydrogen (or proton) pump which transfers
hydrogen from one side of the membrane the other. This creates a
gradient a cross the inner membrane with a higher concentration of
hydrogen ion in the intercrestae space ( The space between inner
and outer membranes). ( Figure 4). The diagram shows the
individual complexes in electron transport chain.
The following diagram shows the individual complex in
the electron transport chain. The elecron are carried
from complex to complex by ubiquinon and cytochrome
C.
In the third pump in the series catalyzes the transfer of
electron to oxygen to make water. This semiosmotic
pumping creates.
An electrochemical proton gradient a cross the
membrane which is used to drive the “Energy Producing
Machine”. The ATP Synthase this molecule is found in
small elementary particle that project from crestae. See
figure 5 ).
Figure 4.
More information figure 5
As started above, this process requires oxygen, which is
called “ aerobic metabolism” The ATP Synthase uses
energy of the hydrogen ion ( also called proton) gradient
to form ATP from ADP and Phosphat. It also produces
water from hydrogen and oxygen. Thus, each
compartement of the mitochondria is specialized for one
phase of this reaction.
How oxidation is coupled to phophorilation
To Review :
NAD and FAD remove the electron that are donated
during some of the steps of the Krebs or citric acid cycle.
Figure 5
Contd
They carried the electron to one electron transport Pump
and donate them to the pump. So NAD and FAD are “
Oxidized” because they loss the hydrogen ion to the
pump. The pump then transport the hidrogens ion to
space between two membranes, where they accumalate
in high enough concentration fuel to the ATP pumps.
With sufficient fuel, they “ Phosphorylate” the ADP : That
is how “ oxidation” is coupled to phosphorilation”.
The hydrogen that get pumped back into the matrix by
ATP pump than combine with oxygen to make water.
And that is very important because, without oxygen, they
will accumulate and the concentration gradient needed
to turn the ATP pump will not allow the pump work.
So, Why do we need mitochondria
The whole idea behind process to get as much ATP out
of glucose (or other food product) as posible. If we have
no oxygen, we get only 4 molecule ATP s for energy
packet each glucose molecule (in glycolysis).
However, if we have oxygen, then we get to run Krebs
cycles to product many more hydrogen ion, can run
those ATP pumps, from the Krebs cycle we get 24- 28
ATP molecules out of one molecule of glucose converted
to pyruvate.
So you can see how much more energy we can get out
of a molecule of glucose, if mitochondria are working,
and if we have oxygen.
Importance of the crestae
Not only do they contain and organize the electron
transport chain and the ATP pump, they also servte to
separate the matrix from the space that will contain the
hydogen ion, allowing the gradient needed to drive the
pump.
As shown in the above diagam, the molecules in the
electron transport chain are found as cluster organized in
the crestae. These membrane sheves maybe more
numerous in mitochondria that are active in production
ATP ( Gambar 6 ).
More information of figure 6
Mitochondria can be separated and the inner and outer
membrane can be dissociated. This will result in a
fraction containing only the inner membrane and matrix.
These have been called : Mitoplast”. They are functional
and have helped us learn more about the
compartementation of mitochondria.
Figure 6 Cyochrome C lying just outside the inner
membrane
Figure 7 Cytochrome is on the inner membrane