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Eukaryotic cells contain organelles including mitochondria, which provide energy for cell functions, chloroplasts, which in plants create sugars by photosynthesis, and ribosomes, which synthesise proteins. Cells were discovered by Robert Hooke in 1665, who named them after their resemblance to cells inhabited by Christian monks in a monastery.
Both organelles, the mitochondria and chloroplasts (in photosynthetic organisms), are compartments that are believed to be of endosymbiotic origin. Other compartments such as peroxisomes , lysosomes , the endoplasmic reticulum , the cell nucleus or the Golgi apparatus are not of endosymbiotic origin.
A mitochondrion (pl. mitochondria) is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi.Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. [2]
The structure and function of cytochrome b 6 f (in chloroplasts) is very similar to cytochrome bc 1 (Complex III in mitochondria). Both are transmembrane structures that remove electrons from a mobile, lipid-soluble electron carrier (plastoquinone in chloroplasts; ubiquinone in mitochondria) and transfer them to a mobile, water-soluble electron ...
Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. The overall reaction occurs in a series of biochemical steps, some of which are redox reactions. Although cellular respiration is technically a combustion reaction , it is an unusual one because of the slow, controlled release of energy from the series ...
In mitochondria, energy released by the electron transport chain is used to move protons from the mitochondrial matrix (N side) to the intermembrane space (P side). Moving the protons out of the mitochondrion creates a lower concentration of positively charged protons inside it, resulting in excess negative charge on the inside of the membrane.
In prokaryotic cells ATP synthase lies across the plasma membrane, while in eukaryotic cells it lies across the inner mitochondrial membrane. Organisms capable of photosynthesis also have ATP synthase across the thylakoid membrane, which in plants is located in the chloroplast and in cyanobacteria is located in the cytoplasm.
The energy derived from the pumping of protons across a cell membrane is frequently used as the energy source in secondary active transport. In humans, sodium (Na + ) is a commonly cotransported ion across the plasma membrane, whose electrochemical gradient is then used to power the active transport of a second ion or molecule against its ...