Expectation value. The number of different alignents with
scores equivalent to or better than S that are expected to
occur in a database search by chance. The lower the E value,
the more significant the score. (NCBI)
This represents the number of sequences with a score greater-than,
or equal to, X, expected absolutely by chance. The E-value connects
the score ("X") of an alignment between a user-supplied
sequence and a database sequence, generated by any algorithm,
with how many alignments with similar or greater scores that
would be expected from a search of a random sequence database
of equivalent size. Since version 2.0 E-values are calculated
using Hidden Markov Models, leading to more accurate estimates
than before. (SMART)
A method of separating large molecules (such as DNA fragments
or proteins) from a mixture of similar molecules. An electric
current is passed through a medium containing the mixture, and
each kind of molecule travels through the medium at a different
rate, depending on its electrical charge and size. Agarose and
acrylamide gels are the media commonly used for electrophoresis
of proteins and nucleic acids. (ORNL)
A process using high-voltage current to make cell membranes
permeable to allow the introduction of new DNA; commonly used
in recombinant DNA technology.
See also: transfection (ORNL)
Embryonic stem (ES) cells
An embryonic cell that can replicate indefinitely, transform
into other types of cells, and serve as a continuous source
of new cells. (ORNL)
Cell or organism with membrane-bound, structurally discrete
nucleus and other well-developed subcellular compartments.
Eukaryotes include all organisms except viruses, bacteria,
and bluegreen algae.
See also: prokaryote, chromosome.