Acetyl CoA
A key intermediate product in the metabolic breakdown of carbohydrates, fatty acids, and amino acids. It consists of a two-carbon acetate group linked to coenzyme A, which is derived from pantothenic acid
ADP (adenosine diphosphate)
A molecule composed of adenosine and two phosphate groups
Aerobic
Referring to the presence of or need of oxygen.
Anabolism
Any metabolic process whereby cells build complex substances from simple, smaller units
Anaerobic
Referring to the absence of oxygen or the ability of a process to occur in the absence of oxygen.
ATP (adenosine triphosphate)
A high-energy compound composed of adenosine and three phosphate groups. It is the main direct fuel that cells use to synthesize molecules, contract muscles, transport substances, and perform other tasks.
Beta-oxidation
The breakdown of a fatty acid into numerous molecules of the two-carbon compound acetyl coenzyme A (acetyl CoA)
Biosynthesis
Chemical reactions in which complex biomolecules, especially carbohydrates, lipids, and proteins, are formed from simple molecules
Carnitine
A compound that transports fatty acids from the cytosol into the mitochondria, where they undergo beta-oxidation
Catabolism
Any metabolic process whereby cells break down complex substances into simpler, smaller ones
Cells
The basic structural units of all living tissues. These have two major parts�the nucleus and cytoplasm
Chemical energy
Energy contained in the bonds between atoms of a molecule
Citric acid cycle
The aerobic metabolic pathway in mitochondria that breaks down acetyl CoA to yield two molecules of carbon dioxide, one molecule of GTP, and pairs of high-energy electrons. It transfers the electrons to three molecules of NAD+ (yielding three NADH) and on
Coenzyme A
A cofactor derived from the vitamin pantothenic
Coenzymes
Organic compounds, often derived from B vitamins, that combine with inactive enzymes to form active enzymes
Cofactors
Compounds required for an enzyme to be active. These include coenzymes and metal ions such as iron, copper, and magnesium
Cytoplasm
The material of the cell, excluding the cell nucleus and cell membranes. This includes the semifluid cytosol, the organelles, and other particles
Cytosol
The semifluid inside the cell membrane, excluding organelles. This is the site of glycolysis and fatty acid synthesis
Electron transport chain
An organized series of protein carrier molecules located in mitochondrial membranes.
Glucogenic
A term describing an amino acid whose carbon skeleton can be used in gluconeogenesis to form glucose
Gluconeogenesis
Synthesis of glucose within the body from noncarbohydrate precursors such as amino acids, lactic acid, and glycerol. Fatty acids cannot be converted to glucose
Glycolysis
The anaerobic pathway that breaks down a glucose molecule into two molecules of pyruvate and yields two molecules of ATP and two molecules of NADH. It occurs in the cytosol of a cell
GTP (guanosine triphosphate)
A high-energy compound, similar to ATP, but with three phosphate groups linked to guanosine instead of adenosine
Ketoacidosis
Acidification of the blood caused by a buildup of ketone bodies. It is primarily a consequence of uncontrolled type 1 diabetes mellitus and can be life threatening
Ketogenesis
The process in which excess acetyl CoA from fatty acid oxidation is converted into ketone bodies
Ketogenic
A term describing an amino acid broken down to acetyl CoA (which can be converted into ketone bodies)
Ketones
Organic compounds that contain a chemical group consisting of C=O (a carbon-oxygen double bond) bound to two hydrocarbons.
Lactate
A three-carbon compound that is produced when insufficient oxygen is present in cells to break down pyruvate to acetyl CoA. Often called lactic acid
Lipogenesis
Synthesis of fatty acids from acetyl CoA derived from the metabolism of fats, alcohol, and some amino acids
Metabolic pathway
A series of chemical reactions that either break down a large compound into smaller units (catabolism) or synthesize more complex molecules from smaller ones (anabolism)
Metabolism
A series of chemical reactions that either break down a large compound into smaller units (catabolism) or synthesize more complex molecules from smaller ones (anabolism)
Metabolites
Substances produced during metabolism
Mitochondria (mitochondrion)
The sites of aerobic production of ATP, where most of the energy from carbohydrate, protein, and fat is captured. Called the "power of plants" of the cell, theese are where the citric acid cycle and electron transport chain are located. A human cell conta
Mitochondrial membrane
The mitochondria are enclosed by a double shell separated by an intermembrane space. The outer membrane acts as a barrier and gatekeeper, selectively allowing some molecules to pass through while blocking others. The inner membrane is where the electron t
NAD+/NADH
Nicotinamide adenine dinucleotide (NAD+), a coenzyme derived from the B vitamin niacin, becomes NADH as it accepts a pair of high-energy electrons for transport in cells
Nucleus
The primary site of genetic information in the cell, enclosed in a double-layered membrane
Organelles
Various membrane-bound structures that form part of the cytoplasm. These perform specialized metabolic functions
Oxaloacetate
A four-carbon intermediate compound in the citric acid cycle.
Photosynthesis
The process by which green plants use light energy from the sun to produce carbohydrates from carbon dioxide and water
Pyruvate
The three-carbon compound that results from glycolysis. Cells also can make glucose from pyruvate, but this process requires energy and several enzymes not involved in glycolysis. It also can be derived from glycerol and some amino acids