allelism is present and the two are mutations at the same gene locus. This is a
simple means of determining whether genetic loci are the same or different.
Allelism A state in which a gene involved in particular phenotype is an allele at a
specific gene locus. In cases involving neighboring genes with very similar
functions (multiple gene families), it is not possible to use genetic exchange to
test whether a single gene locus has different gene types (alleles) or non-alleles
at different gene loci. The allelism ratio is the percentage of alleles (identical
gene loci) for two genes randomly chosen from among these alleles and
non-alleles. The term “lethal allelism” refers to groups of genes that exhibit
lethality due to phenotype.
Allelomorph Phenotype expressed as a result of an allele; in wild types, this refers
to traits governed by mutant alleles. When two or more wild-type alleles are
recognized, they are referred to as multiple alleles. Wild-type traits are typically
dominant and mutant traits recessive (allelomorphic character).
Alloenzymes are variant forms of an enzyme that are coded by different alleles at
the same locus.
Allophycocyanin A type of phycobiliprotein produced by cyanobacteria (except
chlorophyll a and b-containing taxa), glaucophytes, red algae, and
cryptomonads.
Alloxanthin A xanthophyll pigment that is characteristic of photosynthetic
cryptomonads.
Alternation of generation A life history type in which there are two (or more, in
some red algae) multicellular stages that can be distinguished by type of
reproductive cell produced and sometimes also be morphological features.
Alveolata A eukaryotic super group that includes ciliates,
Amoeba A unicellular organism that generates motions via cellular projections
Amoeboid A type of cell organization in which a wall is absent and the protoplasm
undergoes rapid shape changes
Amphiesma The covering of dinoflagellate cells, which, in addition to an
overlying plasma membrane, consists of membranous alveoli that may contain
little or no material or may contain cellulosic thecal plates of varying thickness.
Amplified restriction fragment length polymorphism (AFLP) Technique in
which PCR is used to amplify only a selected part of the genome to analyze
polymorphism in the length of the products.
Androspores Flagellate cells of oedogoniales that settle on body cells near
oogonia and undergo a few divisions to produce a dwarf male filament, some
cells of which produce and release flagellate sperm.
Glossary
419
simple means of determining whether genetic loci are the same or different.
Allelism A state in which a gene involved in particular phenotype is an allele at a
specific gene locus. In cases involving neighboring genes with very similar
functions (multiple gene families), it is not possible to use genetic exchange to
test whether a single gene locus has different gene types (alleles) or non-alleles
at different gene loci. The allelism ratio is the percentage of alleles (identical
gene loci) for two genes randomly chosen from among these alleles and
non-alleles. The term “lethal allelism” refers to groups of genes that exhibit
lethality due to phenotype.
Allelomorph Phenotype expressed as a result of an allele; in wild types, this refers
to traits governed by mutant alleles. When two or more wild-type alleles are
recognized, they are referred to as multiple alleles. Wild-type traits are typically
dominant and mutant traits recessive (allelomorphic character).
Alloenzymes are variant forms of an enzyme that are coded by different alleles at
the same locus.
Allophycocyanin A type of phycobiliprotein produced by cyanobacteria (except
chlorophyll a and b-containing taxa), glaucophytes, red algae, and
cryptomonads.
Alloxanthin A xanthophyll pigment that is characteristic of photosynthetic
cryptomonads.
Alternation of generation A life history type in which there are two (or more, in
some red algae) multicellular stages that can be distinguished by type of
reproductive cell produced and sometimes also be morphological features.
Alveolata A eukaryotic super group that includes ciliates,
Amoeba A unicellular organism that generates motions via cellular projections
Amoeboid A type of cell organization in which a wall is absent and the protoplasm
undergoes rapid shape changes
Amphiesma The covering of dinoflagellate cells, which, in addition to an
overlying plasma membrane, consists of membranous alveoli that may contain
little or no material or may contain cellulosic thecal plates of varying thickness.
Amplified restriction fragment length polymorphism (AFLP) Technique in
which PCR is used to amplify only a selected part of the genome to analyze
polymorphism in the length of the products.
Androspores Flagellate cells of oedogoniales that settle on body cells near
oogonia and undergo a few divisions to produce a dwarf male filament, some
cells of which produce and release flagellate sperm.
Glossary
419