individual will be inclined to perform the same act
back or to another individual. The individual giving
does not necessarily expect anything back, only that
the kindly act will be repeated and benefit society as a
whole.
recognition species concept A concept of species as
a set of individuals that recognize each other as poten-
tial mates; having a common or shared system of mate
recognition, i.e., courtship displays, that ensures mat-
ing with members of the same population.
recombinant An individual where the genotype is
produced by the nonparental arrangement of alleles
that results from independent assortment or crossing
over (recombination); the phenotype individual is dif-
ferent from the parents; also, a term describing a new
combination of genes that form DNA.recombinant DNA Altered DNA that has been
joined, mostly by in vitro means, by genetic material
from two different sources.recombinant DNA technology Refers to the mod-
ern techniques of gene cloning.redox potential Any oxidation–reduction (redox)
reaction can be divided into two half reactions: one in
which a chemical species undergoes oxidation, and
one in which another chemical species undergoes
reduction. If a half-reaction is written as a reduction,
the driving force is the reduction potential. If the half-
reaction is written as oxidation, the driving force is
the oxidation potential related to the reduction poten-
tial by a sign change. So the redox potential is the
reduction/oxidation potential of a compound mea-
sured under standard conditions against a standard
reference half-cell. In biological systems, the standard
redox potential is defined at pH = 7.0 versus the
hydrogen electrode and partial pressure of hydrogen =
1 bar.
See alsoELECTRODE POTENTIAL.redox reaction An abbreviated term for an oxidation-
reduction reaction; a reaction that has both reduction
(electrons are gained) and oxidation (electrons are lost)
occurring; one does not occur without the other.reducing agent The reactant that donates its elec-
trons and in turn becomes oxidized when another
substance is reduced.
See alsoOXIDATION;REDOX REACTION;REDUCTION.reductase SeeOXIDOREDUCTASE.288 recognition species concept
A recessive allele is expressed phenotypically only in offspring
who have received two copies of the recessive gene, one from
each parent.(Courtesy of Darryl Leja, NHGRI, National Institutes
of Health)