Cellular Respiration Flashcards, test questions and answers

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What is Cellular Respiration?

Cellular respiration is one of the most important biological processes, allowing organisms to convert chemical energy stored in nutrients into useable forms of energy. This process plays a critical role in the survival and growth of all living organisms, from bacteria to humans. Cellular respiration occurs in all cells across all species, and involves four major stages. The first stage of cellular respiration is glycolysis, which takes place in the cytoplasm of cells. During this process, glucose molecules are broken down into pyruvate molecules. The energy released during this reaction is used to form adenosine triphosphate (ATP) molecules an important source of energy for the cell. Some pyruvate molecules are then converted into acetyl-CoA molecules and enter the Krebs cycle otherwise known as citric acid cycle or tricarboxylic acid (TCA) cycle which takes place inside mitochondria. In the second stage, acetyl-CoA combines with oxygen and produces carbon dioxide molecules as a byproduct while simultaneously releasing large amounts of energy that is used by the cell to produce ATP molecules, which are essential for all cellular activities including growth and development. After most of its energy requirements have been met through ATP production, some remaining carbon dioxide is converted back into pyruvate that can be recycled back through glycolysis if needed or expelled from the cell as waste gas or liquid depending on species type. The third stage consists of several reactions collectively known as electron transport chain (ETC). In this stage, electrons extracted from glucose during glycolysis are transferred along a series proteins embedded in mitochondrial membranes until they reach oxygen atoms at end point where they combine with hydrogen ions to form water molecule with release large amount high-energy electrons stored within them thus completing ETC process and releasing additional energy that can be used for ATP production or other metabolic activities like fatty acid synthesis or protein synthesis depending upon organism’s requirement at given time.