A simple sugar with the general formula (CH?O)n, where n represents the number
of times the ratio is repeated. Dietary monosaccharides are 6 carbon structures
in the form of five or six-sided rings and include fructose, glucose,
A class of sugars formed via a glycosidic bond between two
monosaccharides. Dietary disaccharides include maltose, sucrose, and
Carbohydrates consisting of three to ten monosaccharide units joined by
Carbohydrates containing thousands of glucose units joined by alpha or beta
glycosidic bonds. Common polysaccharides include glycogen and starch
(amylose or amylopectin).
A structural unit containing a nitrogenous base, a sugar and one or more
phosphate groups. The sugar is a five-sided ring consisting of two hydroxyl
groups, as in ribonucleic acid (RNA), or one hydroxyl group as in
deoxyribonucleic acid (DNA).
A six-carbon monosaccharide composed of hydroxyl groups in its cyclic
form and an aldehyde group in its linear form. In solution, the sugar exists
mostly in its cyclic form and is the primary source of energy in the
A six-carbon monosaccharide consisting of hydroxyl groups
in its cyclic
form and a ketone group in its linear form. In solution, it exists as a five-
membered cyclic structure and is metabolized to a derivative of glucose by
the liver after absorption into the blood.
A six-carbon sugar identical to glucose except that it differs in the three-
dimensional arrangement of one hydroxyl group. Because of this unique
difference, it is known as an epimer of glucose.
A chemical group consisting of an oxygen atom covalently
to a hydrogen atom. Since its electron
density is greatest around the oxygen atom, the group has a polar character to
its bond and is therefore either very hydrophilic or water soluble.
A sugar or other compound differing in three-dimensional configuration about a
single asymmetric center.
A three-dimensional configuration consisting of a six-membered ring in which all
hydroxyl groups face away from the ring in an equatorial position. The
chair conformation is the most energetically stable of all different forms of
the ring. Bonding angles appear in the shape of a chair. For an Organic
Chemistry explanation of chair conformations, see
Slightly less stable than the chair conformation, the boat
conformation consists of a six-membered ring in which some of the
hydroxyl groups face toward the ring. Bonding angles appear in
the shape of a boat. For an Organic Chemistry explanation of chair
An organic chemistry term that helps describes how molecular groups
interfere with other groups in the structure. For an Organic Chemistry
explanation of chair conformations, see
Molecules that have the same chemical formula but different structures.
Compounds containing a carbon-oxygen double bond where two chemical groups
surround the carbon atom. Neither of these chemical groups which are bonded to
the carbon atom can be a hydrogen atom.
Compounds contain a carbon-oxygen double bond where one of the chemical groups
surrounding the carbon atom is a hydrogen atom.
A type of covalent chemical bond that joins two
simple sugars via an oxygen atom. The bond may be either above the plane of the
ring as in a beta glycosidic bond or below the plane as in an alpha glycosidic
Fermentation is the conversion of carbohydrates to form alcohol, acids, or
carbon dioxide without the use of oxygen.
Lactic acid is the product of an oxidation-reduction reaction between the
reduced form of nicotinamide adenine dinucleotide (NADH) and pyruvate. It can
cause muscle cramping and fatigue during exercise.
Coming from the words "without oxygen," anaerobic conditions persist when the
body cannot use oxygen to obtain energy because energy is required at a faster
pace than the electron transport
chain can provide.
Starch is the storage form of glucose in plants. It comes in two different
forms: amylose and amylopectin.
One of the two different forms of starch, amylose is a linear polymer of
glucose joined by repeating alpha glycosidic bonds. Amylose is easily
digested and degraded to glucose by the enzymes in the small intestine.
Similar to amylose, this form of starch is a polymer of glucose
joined by alpha glycosidic linkages. Unlike its cousin, amylopectin is a
highly branched structure due to the fact it contains alpha glycosidic bonds
that are joined at different locations in the glucose polymer. It is easily
digested by the enzymes in the small intestine.
An indigestible polysaccharide, cellulose is an important form of dietary
fiber and is present in many different plants. Due to its glycosidic
linkages and its intramolecular hydrogen bonding, cellulose is very strong
polymer of glucose.
Deoxyribonucleic acid (DNA)
A long polymer of nucleotides joined by phosphate groups, DNA is the genetic
material that provides the blueprint for the proteins that each different cell
will produce in its lifetime. It consists of a five-sided sugar (deoxyribose)
without a free hydroxyl group, a phosphate group linking the two nucleotides and
a nitrogenous base. For more on the structure of DNA, see Structure of
Ribonucleic acid (RNA)
RNA is a long polymer of ribose (a five-sided sugar with a free hydroxyl group)
and nitrogenous bases linked via phosphate groups. It is complementary to one
of the DNA strands and forms the proteins that are specified by the cell. For
more on the structure of RNA, see Structure of Nucleic
Ketosis is a condition in which the incomplete breakdown of fatty acids due
to the decline of glucose in the bloodstream causes the production of
A beta cell is a type of cell found in the pancreas that secretes insulin
into circulation after sensing increasing concentrations of glucose in the
Insulin is a type of hormone secreted into the bloodstream by pancreatic
beta cells in response to increases in blood glucose. Upon binding to
target cells, insulin allows various cell types to uptake glucose for use as an
The process by which substances are produced and discharged from a cell into the
bloodstream (endocrine secretion) or into a separate compartment (exocrine
An alpha cell is a type of cell found in the pancreas that secretes the
hormone glucagons in response to falling levels of glucose.
The process of synthesizing glucose from non-glucose precursors such as
Pyruvate is a three-carbon compound that is formed through the degradation
of glucose via glycolysis. Two pyruvate molecules are formed per molecule
of glucose that enters glycolysis.
A hormone secreted from the adrenal medulla in response to sympathetic
nervous system stimulation and low blood glucose. Its effects include causing
the liver to degrade glycogen into glucose and decreasing the utilization of
glucose by skeletal muscle.
A hormone secreted from the adrenal cortex in response to
emotionally/physically stressful situations. Its effects include the ability to
stimulate the production of new glucose (gluconeogenesis) and decreased
utilization of glucose by cells.
Fatty acids are long hydrocarbon chains that contain a carboxylic acid group at
one end of the molecule. Three fatty acid units and one glycerol unit form a
A four-carbon molecule found in the
that condenses with acetyl CoA to form citrate in the first reaction of the
Krebs cycle. Oxaloacetate must be constantly regenerated in order for the
Krebs cycle and the electron transport
Also known as the Citric Acid Cycle, the Krebs Cycle consists of a series of
reactions that produce high-energy electron carriers to be used in the
transport chain in the production
of adenosine triphosphate (ATP). For more on the Krebs cycle, see Krebs
A molecule produced in the
upon the oxidation of pyruvate and the reduction of nicotinamide adenine
dinucleotide (NAD+) to be used in the Krebs Cycle. It can also be formed
via the degradation of fatty acids.
Diverticula are pouches that protrude through the exterior wall of the large
A pronounced swelling of large veins, particularly those found in the anal
Diverticulitis is a disease in which the diverticula in the large intestine
A multi-ring carbon structure containing one hydroxyl group that is found
only in animal-derived food. It is thought to promote scarring of the arteries
upon deposition along blood vessel endothelia, but it is also known to be a
precursor in the production of steriods.
Any molecule that enters the body through the lungs or gastrointestinal tract
that causes the production of free radicals that can alter a cell's DNA. The
mutation of a single base in DNA can lead to a non-functioning or overactive
protein that may cause the cell to divide uncontrollably: cancer.
Glycolysis is the sequence of reactions that converts glucose into
pyruvate with the simultaneous net production of two molecules of adenosine
Oxidative Phosphorylation is the process of converting adenosine diphosphate
(ADP) to adenosine triphosphate (ATP) via the oxidation-reduction of a series of
electron carriers in the
The Cori Cycle is a process through which lactic acid produced by working
muscle is converted to glucose by the liver. The cycle shifts part of the
metabolic burden to the liver.
A hormone secreted by the adrenal medulla that causes vasoconstriction in
peripheral blood vessels as well as excitation of the heart and inhibition of
the gastrointestinal tract.