Chemistry Reference
In-Depth Information
•
Dipeptide
Formed by the reaction of two amino acids.
•
Disaccharide
Two monosaccharides joined together, for
example maltose.
•
DNA
Abbreviation for deoxyribonucleic acid. It belongs to
a group of biopolymers called the nucleic acids. It is involved
in the polymerisation of amino acids in a specific order to
form the particular protein required by a cell.
•
Drug
Any substance, natural or synthetic, that alters the
way in which the body works.
•
Drug abuse
This term usually applies to the misuse
of addictive drugs, which include barbiturates and
amphetamines, as well as the opiates, cocaine and heroin.
These drugs create severe psychological and physiological
problems. This leads to a variety of personal problems for
the user.
•
Esters
A family of organic compounds formed by the
reaction of an alcohol with a carboxylic acid in the presence
of concentrated H
2
SO
4
. This type of reaction is known
as esterification. Esters are characterised by a strong and
pleasant smell (many occur in nature and account for the
smell of flowers).
•
Fermentation
A series of biochemical reactions brought
about by the enzymes in yeast or, more generally, by micro-
organisms.
•
Functional group
The atom or group of atoms
responsible for the characteristic reactions of a compound.
•
Genetic engineering
The deliberate manipulation of the
genes in an organism.
•
HIV
Short for human immunodeficiency virus, from which
AIDS (acquired immunodeficiency syndrome) can develop.
•
Hydrolysis
A chemical reaction involving the reaction of a
compound with water. Acid hydrolysis usually involves dilute
hydrochloric acid, and enzyme hydrolysis involves enzymes
such as amylase.
•
Monosaccharides
A group of simple carbohydrates.
They are sweet to taste and are water soluble (for example,
glucose).
•
Pharmaceuticals
These are chemicals called drugs that
are prepared and sold with the intention of treating disease
(for example, methyldopa).
•
Polyamide
A condensation polymer, such as nylon, that
contains the amide link, -NHOC-.
•
Polysaccharides
A group of more complicated
carbohydrates. They generally do not form true solutions
and do not have a sweet taste (for example, starch).
•
Proteins
Polymers of amino acids formed by condensation
reactions. They fall broadly into two categories: fibrous
proteins (for example, keratin and collagen) and globular
proteins (for example, casein and albumen).
•
Saponiication
A reaction in which an ester is heated
with an alkali, such as sodium hydroxide, producing a free
alcohol and an acid.
•
Soapless detergents
Soap-like molecules which do
not form a scum with hard water. These substances
have been developed from petrochemicals. Their calcium
and magnesium salts are water soluble and they are
biodegradable.
•
Soaps
Substances formed by saponification. In this
reaction, the oil or fat (glyceryl ester) is hydrolysed by
aqueous sodium hydroxide to produce the sodium salt of
the fatty acid, particularly sodium stearate (from stearic
acid). Soap will dissolve grease because of the dual
nature of the soap molecule. It has a hydrophobic part
(the hydrocarbon chain) and a hydrophilic part (the ionic
head) and so will involve itself with both grease and water
molecules. However, it forms a scum with hard water by
reacting with the Ca
2
+
(or Mg
2
+
) present.
