Why the mitochondria is called the powerhouse of the cell?

Mitochondria are double membrane-bound organelles found in the cytoplasm of nearly all eukaryotic cells. They are often described as the "powerhouses" of the cell due to their primary role in generating adenosine triphosphate (ATP), the main energy currency of the cell.
Mitochondria (singular = mitochondrion) were first discovered by Albert vonkollicker in 1850 from striated muscle tissue of insects and the term "mitochondrion" (In Greek, Mito = "thread" + chondrion = "granule") was coined by Carl Benda because of the thread like appearance of these granules when examined under light microscope.

Structure of Mitochondria

Mitochondria occupy up to 25% volume of the cytoplasm. A mitochondrion is enclosed by a double membrane.
  • Outer Membrane: Permeable barrier with porins for metabolite exchange. Outer membrane is constituted by 50% lipids and 50% proteins along with porin protein (conferring permeability to molecules with molecular weight as high as 10,000).
  • Intermembrane Space: Contains enzymes and proteins for transport and phosphorylation.
  • Inner Membrane: Selectively permeable, rich in proteins for the electron transport chain, and forms cristae. Inner membrane is constituted by 80% proteins and 20% lipids.
  • Cristae: Cristae are folds in the inner membrane of mitochondria. They increase the surface area for ATP production.
  • Matrix: Contains enzymes for the Krebs cycle, mitochondrial DNA, and machinery for protein synthesis.
  • Mitochondrial DNA: Encodes some of the proteins needed for mitochondrial function, allowing for some independence in replication and protein synthesis.

Why Called the "Powerhouse" of the Cell?

Mitochondria are called the "powerhouse of the cell" because they are responsible for producing the majority of the cell's energy in the form of adenosine triphosphate (ATP), which powers virtually all cellular activities. The nickname arises from their role in converting chemical energy from nutrients into a usable form of energy that the cell can utilize, much like a power plant converts raw materials into electricity to power a city.

Here are key points that explain why mitochondria are called the "powerhouses" of the cell:

01. ATP Production (Energy Currency):

Mitochondria are the primary site for aerobic respiration, a process that produces ATP, the energy molecule that cells rely on to perform essential functions like growth, repair, movement, and biochemical reactions. Cells use ATP as the energy currency, meaning it provides the energy required for processes such as muscle contraction, active transport, and cell division. Without the ATP produced by mitochondria, cells would be unable to function efficiently.

02. Efficient Energy Conversion:

Mitochondria perform a highly efficient form of energy production through cellular respiration, particularly the processes of the Krebs cycle and oxidative phosphorylation. These processes involve breaking down glucose, fatty acids, and oxygen into energy. Mitochondria can produce up to 36 ATP molecules per molecule of glucose, a far more efficient energy yield than the 2 ATP molecules produced through anaerobic respiration, which occurs without oxygen outside the mitochondria. This high efficiency in energy generation is why they are likened to power plants.

03. Oxidative Phosphorylation:

One of the most crucial processes in mitochondria is oxidative phosphorylation, which takes place in the inner mitochondrial membrane. This process uses a gradient of protons (H⁺) across the inner membrane to power the enzyme ATP synthase, which converts ADP (adenosine diphosphate) into ATP. This is the most significant part of the ATP generation process and the key reason mitochondria are called the "powerhouse." It's the same as how a power plant converts raw energy sources like coal or gas into electricity mitochondria convert food into a form of energy the cell can use.

04. Energy Supply to the Entire Cell:

The energy produced by the mitochondria in the form of ATP is distributed throughout the cell to drive various processes, including chemical reactions, ion transport, and synthesis of macromolecules. In this way, mitochondria act as the cell's power generators, continuously providing energy to meet the cell's needs. If the mitochondria fail, the cell would lose its energy supply and eventually die, just as a city would fail without a power source.

05. Adaptability to Energy Demands:

Cells with high energy demands, like muscle cells and brain cells, contain a greater number of mitochondria. This ensures that these energy-intensive cells have sufficient ATP to carry out their functions. Mitochondria can also adjust their energy output based on the needs of the cell, much like how power plants adjust electricity production based on demand. This adaptability reinforces their role as the "powerhouse" of the cell.



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SAQ 1

  1. What is a cell? What are the essential characteristics of cells?
  2. Explain the fluid mosaic model of the plasma membrane
  3. Which organelles are involved in photosynthesis?
  4. Why the mitochondria is called the powerhouse of the cell?
  5. Which organelle contains enzymes for cellular respiration?
  6. Why mitochondria and chloroplast are called semi-autonomous?
  7. Mention any two advantages of the extensive network of the endoplasmic reticulum
  8. What is the function of peroxisomes in plant cells?
  9. Explain the following terms: (a) chromatin network (b) chromosomes (c) Nucleosome (d) Solenoid Model
  10. What is the function of the nucleolus in the cell?

SAQ 2



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