what is the funtion of a mitochondria in a cell?

Answer 1

Mitochondrial functions
Although it is well known that the mitochondria converts organic materials into cellular energy in the form of ATP, mitochondria play an important role in many metabolic tasks, such as:

Apoptosis-programmed cell death
Glutamate-mediated excitotoxic neuronal injury
Cellular proliferation
Regulation of the cellular redox state
Heme synthesis
Steroid synthesis
Heat production (enabling the organism to stay warm).
Some mitochondrial functions are performed only in specific types of cells. For example, mitochondria in liver cells contain enzymes that allow them to detoxify ammonia, a waste product of protein metabolism. A mutation in the genes regulating any of these functions can result in a variety of mitochondrial diseases.


Energy conversion
As stated above, the primary function of the mitochondria is the production of ATP. This is done by metabolizing the major products of glycolysis: pyruvate and NADH (glycolysis is performed outside the mitochondria, in the host cell's cytosol). This metabolism can be performed in two very different ways, depending on the type of cell and the presence or absence of oxygen.


Pyruvate: the citric acid cycle
Main article: citric acid cycle
Each pyruvate molecule produced by glycolysis is actively transported across the inner mitochondrial membrane, and into the matrix where it is combined with coenzyme A to form acetyl CoA. Once formed, acetyl CoA is fed into the citric acid cycle , also known as the tricarboxylic acid (TCA) cycle or Krebs cycle. This process creates 3 molecules of NADH and 1 molecule of FADH2, which go on to participate in the electron transport chain.

With the exception of succinate dehydrogenase, which is bound to the inner mitochondrial membrane, all of the enzymes of the citric acid cycle are dissolved in the mitochondrial matrix.


NADH and FADH2: the electron transport chain
Main article: electron transport chain
The redox energy from NADH and FADH2 is transferred to oxygen (O2) in several steps via the electron transport chain. Protein complexes in the inner membrane (NADH dehydrogenase, cytochrome c reductase and cytochrome c oxidase) perform the transfer and the incremental release of energy is used to pump protons (H+) into the intermembrane space. This process is efficienct but a small percentage of electrons may leak prematurely to oxygen, forming the toxic free radical superoxide. This can cause oxidative damage in the mitochondria and may contribute to the decline in mitochondrial function associated with the aging process.

As the proton concentration increases in the intermembrane space, a strong electrochemical gradient is built up across the inner membrane. The protons can return to the matrix through the ATP synthase complex and their potential energy is used to synthesis ATP from ADP and inorganic phosphate (Pi). This process is called chemiosmosis and was first described by Peter Mitchell who was awarded the 1978 Nobel Prize in Chemistry for his work. Later, part of the 1997 Nobel Prize in Chemistry was awarded to Paul D. Boyer and John E. Walker for their clarification of the working mechanism of ATP synthase.

Under certain conditions, protons may be allowed to re-enter the mitochondial matrix without contributing to ATP synthesis. This process, known as proton leak or mitochondrial uncoupling, results in the unharnessed energy being released as heat. This mechanism for the metabolic generation of heat is employed primarily in specialized tissues, such as the brown fat of newborn or hibernating mammals, brown in colour due to high levels of mitochondria.

Answer 2

mitochondria are known as the "power house" of the cell because they "create" (via cellular respiration) the majority of the energy used by the cell.

Answer 3

mitchondria create ATP which is used by the cell for energy.

Answer 4

It is the center of energy production.