Glossary
allele One of
two or more alternative forms of a gene that exist at a specific gene location
on a chromosome.
amino acid
The fundamental chemical subunit of proteins. There are 20 common amino
acids.
bacteriophage
A virus that infects bacteria. Also called a phage.
chromosomes
Long thread-like structures made of DNA and protein that are the gene-bearing
structures of eukaryotic cells.
codon A three-nucleotide
sequence that codes for a specific amino acid or a stop signal in protein
synthesis.
denaturation
A process in which a protein's structure is altered, causing the protein
to become biologically inactive.
deoxyribonucleic acid (DNA)
A double-stranded, helical nucleic acid molecule that is the carrier of
genetic information.
DNA ligase
An enzyme that can join nucleotides in a DNA strand.
DNA replication
The copying of a DNA molecule.
DNA sequencing
The process of deciphering the precise order of nucleotide bases in a DNA
molecule.
electrophoresis
The separation and identification of molecules based on their movement through
an electrically charged field.
enol form A form
of guanine or thymine in which a hydrogen atom bonds to a nearby oxygen
atom that sticks out from the nitrogen ring of the base.
enzymes A class
of proteins that act as catalysts, chemical agents that change the rate
of a reaction without being consumed by the reaction.
gene A discrete
unit of hereditary information that is located on the chromosomes and consists
of DNA.
gene cloning
The process of synthesizing multiple copies of a particular DNA sequence
using a bacterial cell or another organism as a host.
genetic code
The set of sixty-four codons corresponding to each of the 20 amino acids.
genetic engineering
The technique of altering the genetic makeup of cells or organisms by deliberately
inserting, removing, or altering individual genes.
heterozygous
Having two different alleles for a given trait.
helix Having a
spiral, coiled form such as a screw thread or a spring.
isomers Molecules
with the same chemical composition but with different chemical structures.
keto form A
form of guanine or thymine in which a hydrogen atom bonds to a nitrogen
atom within the nitrogen ring of the base.
nitrogenous base
One of four nitrogen containing bases - adenine, thymine, guanine, and cytosine
- that make up nucleotides.
nucleic acid
An acid compound, such as DNA or RNA, that is found in the nucleus of a
cell.
nucleotides
A chemical subunit composed of a five-carbon sugar, bonded to a phosphate
group and nitrogenous base, which makes up the nucleic acids.
plasmids A circular,
self-replicating form of DNA found in many species of bacteria. Plasmids
can sometimes be used as a vector to transfer recombinant genes into another
species.
protein A molecular
chain containing amino acid subunits linked together in a specific sequence.
purines One of
two families of nitrogenous bases found in nucleotides. Two members are
adenine and guanine.
pyrimidines
One of two families of nitrogenous bases found in nucleotides. Two members
are cytosine and thymine.
recombinant DNA (rDNA)
A DNA sequence produced artificially by joining pieces of DNA from different
organisms.
restriction
enzyme An enzyme that cuts DNA molecules at a specific base sequence.
RNA A single-stranded
nucleic acid involved in protein synthesis. The structure of RNA is determined
by DNA.
tautomers Two
or more isomers which have a different placement of a hydrogen atom and
can exist in equilibrium.
vector A plasmid,
virus, or other vehicle that is used to move a recombinant DNA sequence
into the cell of another organism.
X-ray crystallography
A technique that involves the use of X-ray photographs to study the arrangement
of atoms, ions, or molecules in substances.
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Resource Book Index: Stories from the Scientists
