Metabolism 101

What is Metabolism

In biology, metabolism is the set of life-sustaining chemical transformations within the cells of living organisms. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. The word metabolism can also refer to all chemical processes involved in living, including digestion and the transport of substances into and between different cells, in which case the set of processes must be jointly referred to as "metabolism" and "bioenergetics".

Dennis Howard

View

Metabolism 101

Free Energy and Spontaneity

In thermodynamics, the free energy is a thermodynamic potential that is a function of the state of a system and its environment. The free energy is a generalization of the enthalpy (or heat content) to include the effects of volume and temperature, which are represented as the third and fourth terms in the Taylor series expansion of the free energy. The free energy is a state function, as opposed to the internal energy, which refers to a specific point in a thermodynamic system.

Dennis Howard

View

Metabolism 101

ATP

Adenosine triphosphate (ATP) is a nucleotide used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism. It is produced by photophosphorylation and cellular respiration and used by enzymes and structural proteins in many cellular processes, including biosynthetic reactions, motility, and cell division. Most biological processes depend in part on ATP.

Dennis Howard

View

Metabolism 101

How Nonspontaneous Reactions Go

In biochemistry, a metabolic reaction is a chemical reaction that takes place in a living organism to sustain life. The chemical reactions of metabolism are organized into metabolic pathways. Metabolic reactions may be 'nonspontaneous', in which the reactants are directly involved in the reaction, or 'spontaneous', in which case the reactants are not directly involved in the reaction; instead a catalyst is required to trigger the reaction. In general, metabolic reactions involve the making or breaking of chemical bonds. The reactants in a reaction are often chemical compounds such as sugars, lipids, amino acids, and nucleic acids. The bonds include covalent bonds, ionic bonds, and hydrogen bonds. Enzymes are crucial to metabolism because they allow organisms to drive chemical reactions in a certain direction, as well as to determine the speed of these reactions.

Dennis Howard

View

Metabolism 101

Enzymes

Enzymes are proteins that catalyze chemical reactions. They are biological catalysts that speed up reactions without themselves being used up. Enzymes are essential for all living organisms, as they allow reactions to take place with a very high rate and under mild conditions. In humans, enzymes are responsible for the digestion of food, the breakdown of molecules in the blood, the repair of DNA, the synthesis of proteins, and the metabolism of drugs and other xenobiotics.

Dennis Howard

View

Metabolism 101

Enzymes II

Dennis Howard

View

Metabolism 101

Types of Reactions

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.

Dennis Howard

View

Metabolism 101

Metabolic Regulation

In biology, metabolism is the set of life-sustaining chemical transformations within the cells of living organisms. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. The word metabolism can also refer to the aggregate of biochemical processes occurring in an organism. In either case, the processes include the chemical reactions of macromolecules, particularly proteins, which are involved in metabolism and also the set of chemical reactions that break down the macromolecules of the organism and its wastes to allow maintenance and growth.

Dennis Howard