25
Dec
2009
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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

A

A
(1) In DNA or RNA, adenine. (2) In proteins, alanine.
acceptor site
The 3' end of an intron.
acctran
Accelerated transformation in parsimony reconstruction.
active site
Part of a protein, usually an enzyme, the structural integrity of which is required for function (e.g., substrate binding).
additive tree
A phylogenetic tree in which the distance between any two terminal nodes is equal to the sum of the branch lengths connecting them.
advantageous mutation
A mutation that increases the fitness of the organism carrying it.
AIC
Akaike Information Criterion.
AICc
Corrected Akaike Information Criterion.
alignment
The pairing of two homologous sequences for the purpose of identifying the location of insertions and deletions.
allele (allelomorph)
Alternative form of a gene at a locus.
allele frequency (gene frequency)
The percentage of the copies of an allele at a given locus in a population.
allozyme (allelozyme)
An allelic form of an enzyme.
alpha value
The probability of rejecting a null hypothesis when the null hypothesis is actually true (type I error).
alternative splicing
The production of two or more mRNA molecules from a single pre-mRNA sequence by using different acceptor and donor sites.
amino acid
An organic molecule of the general formula RCH(NH2)COOH, possessing both basic (NH2) and acidic (COOH) groups, as well as a side group (R) specific for each amino acid. The subunit building block of proteins.
amino terminal (N-terminal)
The NH2 end of a polypeptide.
amphioxus
Branchiostoma spp.; lancelet.
amplification
A large increase in the number of copies of a gene or a DNA sequence beyond that which is characteristic of the organism's haploid genome.
analogy
Similarity by convergent evolution, but not by common evolutionary ancestry.
aneuploidy (chromosomal duplication)
The presence of extra chromosomes, such that the chromosomal composition of a cell is not an exact multiple of the haploid set.
anticodon
A triplet of nucleotides in a tRNA molecule that associates by complementary base pairing with a specific codon in the mRNA during translation, and specifies the placement of a particular amino acid during translation.
antiparallel
The opposite orientation of the two complementary strands of a DNA duplex.
apomorphy
Derived character state.
apoprotein
A protein without the coenzymes, cofactors, and prosthetic groups that are required for its functionality (e.g., apolipoprotein).
archaebacteria
Prokaryotes that do not incorporate muramic acid into their cell walls. A highly diverse group of methanogenic (producing methane), thermophilic, acidophilic, and hallophilic (living in high salt concentrations) bacteria that is presumed to represent one of the three primary lines of descent in the living world.
arithmetic mean
The sum of n terms divided by n.
autapomorphy
Character state unique to a single OTU.
autosome
Any chromosome other than a sex chromosome.