Mitochondrion: Definition, Function & Structure

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  • 0:04 Definition of a Mitochondrion
  • 1:03 Mitochondria vs Other…
  • 1:54 Mitochondria Size,…
  • 2:45 Lesson Summary
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Lesson Transcript
Instructor: Jeremy Battista
In this lesson, we'll learn about a microscopic structure known as a mitochondrion, one of many organelles responsible for a lot of what goes on inside of us. We'll discover how mitochondria are structured and work, as well as why they're so important to cells and all living things.

Definition of a Mitochondrion

A mitochondrion is an organelle, a specialized structure found inside almost all eukaryotic cells. Eukaryotic cells contain a nucleus and membrane-bound organelles, like mitochondria. Mitochondria have been called the powerhouse of the cell because of their role in cellular respiration and energy production. Without mitochondria, we would not be able to properly use our energy and live.

Cellular respiration occurs when oxygen breaks down food molecules and generates energy (ATP). Check out the diagram below:


You might notice that cellular respiration is occurring primarily within the mitochondrion. It's important to note that cellular respiration is the means by which we use materials to create energy for our basic metabolic processes. Without cellular respiration, we would not be able to function and live; and yes, all living things utilize some form of cellular respiration, including plants that also rely upon photosynthesis.

Mitochondria vs. Other Organelles

Mitochondria are similar to other organelles in that they are covered with their own membranes. They differ in that their membranes are the result of free-floating ribosomes found within the surrounding cytosol, as well as ribosomes contained inside the mitochondria. Cytosol is a water-soluble component of cytoplasm, which is located within the cell membrane. Ribosomes are tiny organelles composed of ribonucleic acid (RNA), and they play an important part in protein synthesis.

Mitochondria also contain a small amount of deoxyribonucleic acid - or DNA, as it's better known - which is the instructional material used to help program proteins made by the mitochondria's ribosomes. Mitochondria are considered semiautonomous because they can grow and reproduce of their own accord without instructions from the nucleus.

Mitochondria Size, Shape, Structure

Take a look at the diagram below:

Mitochondria open-view

You're looking at a cross-sectional view of a mitochondrion. Note the folds, or cristae, in the inner membrane.

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