Scientists Say: Mitochondrion | Science News for Students

Scientists Say: Mitochondrion

This structure produces energy for a cell
May 22, 2017 — 6:50 am EST

These two round structures are mitochondria from a mammal’s lung. The stripes inside are extra membrane surface area that helps them produce energy for their cell.

Louisa Howard/Wikimedia Commons

Mitochondrion, plural mitochondria (noun, “MITE-oh-CON-dree-on”, plural “MITE-oh-CON-dree-ah”)

These are structures inside cells that convert glucose, a type of sugar, into adenosine triphosphate or ATP. This molecule provides energy a cell can use for all its needs.

Most cells in your body, except red blood cells, have mitochondria. A single liver cell may have as many as 2,000. Unlike most other cellular structures, each mitochondrion has its own DNA — a molecular code that controls its function. This might be because mitochondria originated as free-living bacteria. At some point in the very distant past, one of those bacteria may have been gobbled up by a bigger cell. But it didn’t get digested. Instead, the mitochondrion may have produced energy that the bigger cell could use. It would have been the start of a beautiful relationship.

In a sentence

The DNA inside mitochondria can be used to figure out animal ancestry, such as when wolves turned into dogs.

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Power Words

(more about Power Words)

adenosine     A molecule in the body made from a sugar bound to a nitrogen-based material. It helps the body transport energy in molecules such as ATP. It also promotes sleep in people.

adenosine triphosphate      (ATP) This is a molecule that cells make to power almost all of their activities. Cells use oxygen and simple sugars to create this molecule, the main source of their energy. The small structures in cells that carry out this energy-storing process are known as mitochondria. Like a battery, ATP stores a bit of usable energy. Once the cell uses it up, mitochondria must recharge the cell by making more ATP using energy harvested from the cell’s nutrients.

bacteria     ( singular: bacterium ) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals).

cell     The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Some organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

DNA     (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

glucose     A simple sugar that is an important energy source in living organisms. As an energy source moving around the bloodstream, it may be known as “blood sugar.” It is half of the molecule that makes up table sugar (also known as sucrose).

liver     An organ of the body of animals with backbones that performs a number of important functions. It can store fat and sugar as energy, break down harmful substances for excretion by the body, and secrete bile, a greenish fluid released into the gut, where it helps digest fats and neutralize acids.

mitochondria     (sing. mitochondrion ) Structure in all cells (except bacteria and archaea) that break down nutrients and convert them into a form of energy known as ATP.

nutrient     A vitamin, mineral, fat, carbohydrate or protein that a plant, animal or other organism requires as part of its food in order to survive.

red blood cell     Colored red by hemoglobin, these cells move oxygen from the lungs to all tissues of the body. Red blood cells are too small to be seen by the unaided eye.


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