The word "locus" is correct and usable in written English
It is a noun meaning "the precise point at which something is located or a center of activity, attention, or concentration." For example, "The locus of power in the town shifted from the mayor's office to the local university."
If the two loci are perfectly linked, then the set of gametes produced by the A1B1 / A2B2 double heterozygote has the composition {½ A1B1, ½ A2B2}; this means that if a gamete receives the A1 allele at the A locus, it necessarily receives the B1 allele at the B locus and vice versa.
For philosophers who treat the individual knower as the primary locus of inquiry, rationality, and knowledge, the phenomena of the coexistence, however uneasy, of difference (even dissent) and of the ascendance of new ideas are the most salient features of a social community.
Other physical theories have gone beyond the neural and placed the natural locus of consciousness at a far more fundamental level, in particular at the micro-physical level of quantum phenomena.
With revolution we immediately confront the problem of deep, possibly noncumulative, conceptual and practical change, now in modern science itself, a locus that Enlightenment thinkers would have found surprising.
With respect to the locus in question, there are three possible genotypes in the population, A1A1, A1A2 and A2A2 (just as in Mendel's pea plant example above).
Suppose that at a given locus, or chromosomal 'slot', there are two possible alleles, A1 and A2; the locus is assumed to be on an autosome, not a sex chromosome.
For the multi-allelic case, suppose there are n alleles at the locus, A1 … An, with relative frequencies of p1 … pn respectively, where p1 + p2 + … + pn = 1.
That this is so is clear for if we know the relative frequencies of all the alleles (at a single locus), and know that the population is in Hardy-Weinberg equilibrium, the entire genotype frequency distribution can be easily computed.
The simplest population-genetic model of natural selection assumes one autosomal locus with two alleles, A1 and A2, as above.
This simple derivation of the Hardy-Weinberg principle deals with two alleles at a single locus, but can easily be extended to multiple alleles.
