TABLE 38–1. Glossary of common genetics terms
Alternative form or variant of a DNA marker.
Unit of genetic map distance defined as the distance
between two loci with a 1% probability of recombination,
corresponding to approximately 1 million base pairs (1 Mb).
Phenotypes arising from the effects of multiple genes
and their interactions with the environment.
Cell containing two copies (2N) of each chromosome.
Phenomenon by which genes interact with each other,
as when translated products of one gene serve as regulator agents
at the promoter regions of other genes.
Portions of the gene that express mature RNA and proteins.
Segment of DNA that encodes functional products.
When increasing numbers of trinucleotide repeats over
successive generations create increased risk for illness.
Sum of heritable material found in an individual's
Study of the function and structure of the genome.
Cell containing one copy (N) of each chromosome.
Particular pattern of inherited alleles at multiple
DNA markers in close proximity within a chromosomal region.
Polymorphisms resulting from addition /removal
of nucleotides from a gene.
Regions of the gene that code nucleic acid segments
that are interspersed between exons and excised prior to RNA translation.
Law of equal segregation
Mendel's postulate that each sperm or egg
receives one allele per gene from each parent, with an equal chance
of receiving one or the other of the parents' two alleles.
Law of independent assortment
Mendel's postulate that the segregation of
allele pairs for one trait into separate eggs or sperm is independent
from the segregation of other traits.
Fixed position on a chromosome.
Inheritance following Mendel's laws of equal
segregation and independent assortment. Applies to nonlinked simple
traits in which alleles demonstrate dominant or recessive effects.
Alteration in DNA nucleotide base sequence that results
from copying errors or exposure to environmental toxins.
Molecule comprising a nucleotide base, five-carbon
sugar, and one to three phosphate groups, that when linked in a
chain forms the basic structural unit of DNA and RNA.
Single nucleotide changes within a gene.
Allele variant or mutation occurring in >1% of
Differences in allele frequencies among different racial
and ethnic groups.
Phenotypes arising from changes in single genes.
Single nucleotide polymorphism (SNP)
Single nucleotide base that varies among individuals
in a population, resulting from random mutations over human history.
Trinucleotide repeat insertions
Repetitions of three nucleotide base pair units within
Variable number tandem repeat (VNTR)
Common polymorphism in which a base pair insertion
repeats itself a variable number of times.