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Molecular Biology and Computational Biology Glossary
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(Continued from previous part...)
H
H is the relative entropy of the target and background residue
frequencies. (Karlin and Altschul, 1990). H can be thought of
as a measure of the average information (in bits) available
per position that distinguishes an alignment from chance. At
high values of H, short alignments can be distinguished by chance,
whereas at lower H values, a longer alignment may be necessary.
(Altschul, 1991)
Haploid
A single set of chromosomes (half the full set of genetic
material) present in the egg and sperm cells of animals and
in the egg and pollen cells of plants. Human beings have 23
chromosomes in their reproductive cells.
Haplotype
A way of denoting the collective genotype of a number of closely
linked loci on a chromosome.
Hemizygous
Having only one copy of a particular gene. For example, in
humans, males are hemizygous for genes found on the Y chromosome.
Hereditary
cancer
Cancer that occurs due to the inheritance of an altered gene
within a family.
Heterozygosity
The presence of different alleles at one or more loci on homologous
chromosomes. (ORNL)
Heterozygote
Highly conserved sequence
DNA sequence that is very similar across several different
types of organisms.
High-throughput sequencing
Homeobox
A short stretch of nucleotides whose base sequence is virtually
identical in all the genes that contain it. Homeoboxes have
been found in many organisms from fruit flies to human beings.
In the fruit fly, a homeobox appears to determine when particular
groups of genes are expressed during development.
Homolog
A member of a chromosome pair in diploid organisms or a gene
that has the same origin and functions in two or more species.
Homologous chromosome
Chromosome containing the same linear gene sequences as another,
each derived from one parent.
Homologous recombination
Swapping of DNA fragments between paired chromosomes.
Homology
Similarity attributed to descent from a common ancestor.
Homology
Similarity in DNA or protein sequences between individuals
of the same species or among different species.
Homology
Evolutionary descent from a common ancestor due to gene duplication.
Homozygote
An organism that has two identical alleles of a gene.
Homozygous
HSP
High-scoring segment pair. Local alignments with no gaps that
achieve one of the top alignment scores in a given search.
Human gene
therapy
Human Genome Initiative
Collective name for several projects begun in 1986 by DOE to
create an ordered set of DNA segments from known chromosomal
locations, develop new computational methods for analyzing genetic
map and DNA sequence data, and develop new techniques and instruments
for detecting and analyzing DNA. This DOE initiative is now
known as the Human Genome Program. The joint national effort,
led by DOE and NIH, is known as the Human Genome Project. (ORNL)
Human Genome Project (HGP)
Formerly titled Human Genome Initiative.
Hybrid
The offspring of genetically different parents.
Hybridization
The process of joining two complementary strands of DNA or
one each of DNA and RNA to form a double-stranded molecule.
(Continued on next part...)
Part:
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U
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W
X
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Z
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