25
Dec
2009
admin

Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

H

H
Histidine.
haploid
A cell or organism having a single set of unpaired chromosomes.
haploid set
The chromosomes in a haploid cell or individual.
haplotype
The specific allelic constitution of a chromosome. Often, the allelic composition of one or a few linked genes under investigation.
Hardy-Weinberg equilibrium
A condition under which the genotypic frequencies in a diploid population are equal to the products of the allele frequencies involved.
heteroduplex
A double-stranded nucleic acid molecule in which each strand has been derived from a different individual.
heterogeneous nuclear RNA (heterogeneous RNA, heteronuclear RNA, hnRNA)
RNA transcripts in the nucleus, representing precursors and processing intermediates of rRNA, mRNA, and tRNA, as well as mature RNA transcripts not yet transported into the cytoplasm.
heterosis
(see overdominance)
heterozygous advantage
(see overdominance)
heuristic
An algorithm that cannot be shown to find an optimal solution.
highly repetitive DNA
The fraction of genomic DNA consisting of sequences repeated on the average hundreds or thousands of times.
highly repetitive genes
Functional genes appearing in numerous copies in the haploid genome.
homoduplex
A double-stranded DNA, the complementary strands of which are derived from the same individual.
homology
Similarity by common ancestry or genetic relatedness.
homoplasy
Similarity in state as opposed to similarity by descent.
homozygote
A diploid individual with identical alleles at one or more loci.
horizontal evolution
(see concerted evolution)
hotspot of mutation
A segment of genomic DNA that shows a high propensity to mutate either spontaneously or under the action of a particular mutagen.
hybrid dysgenesis
A syndrome of correlated abnormalities that is spontaneously induced in one type of hybrid between certain mutually interactive strains of Drosophila, but not in the reciprocal hybrid.
hybrid vigor
(see overdominance)
hypervariable site or hypervariable region
A DNA or protein region that exhibits excessive intraspecific variability. Maintenance of so much variability usually requires the locus to be subject to a form of balancing selection, such as overdominance.