Science / Genetics Glossary

Phenotype: Observable characteristics of an organism produced by the organism's genotype interacting with the environment.

Physical Map: A map of the locations of identifiable landmarks on dna (e.g., restriction enzyme cutting sites, genes), regardless of inheritance. Distance is measured in base pairs. For the human genome, . . . View Full Definition

Pku: Phenylketonuria, an enzyme deficiency condition characterized by the inability to convert one amino acid, phenylalanine, to another, tyrosine, resulting in mental deficiency. Plasmid double- . . . View Full Definition

Plasmid: Autonomously replicating extra-chromosomal circular dna molecules, distinct from the normal bacterial genome and nonessential for cell survival under nonselective conditions. Some plasmids a . . . View Full Definition

Pleiotropy: The phenomenon of variable phenotypes for a number of distinct and seemingly unrelated phenotypic effects.

Pluripotency: The potential of a cell to develop into more than one type of mature cell, depending on environment.

Polycystic Kidney Disease (PKD): A group of conditions characterized by fluid filled sacs that slowly develop in both kidneys, eventually resulting in kidney malfunction.

Polygenic Disorder: Genetic disorder resulting from the combined action of alleles of more than one gene (e.g., heart disease, diabetes, and some cancers). Although such disorders are inherited, they depend on . . . View Full Definition

Polygenic Disorders: Genetic disorders resulting from the combined action of alleles of more than one gene (e.g., heart disease, diabetes, and some cancers). Although such disorders are inherited, they depend on . . . View Full Definition

Polymerase: Any enzyme that catalyzes the formation of dna or rna from deoxyribonucleotides or ribonucleotides.

Polymerase (DNA Or RNA): Enzymes that catalyze the synthesis of nucleic acids on preexisting nucleic acid templates, assembling rna from ribonucleotides or dna from deoxyribonucleotides.

Polymerase Chain Reaction (PCR): A method for amplifying a dna base sequence using a heat- stable polymerase and two 20- base primers, one complementary to the (+)- strand at one end of the sequence to be amplified and the . . . View Full Definition

Polymorphism: Difference in dna sequence among individuals that may underlie differences in health. Genetic variations occurring in more than 1% of a population would be considered useful polymorphisms fo . . . View Full Definition

Polypeptide: A protein or part of a protein made of a chain of amino acids joined by a peptide bond.

Population Genetics: The study of variation in genes among a group of individuals.

Positional Cloning: A technique used to identify genes, usually those that are associated with diseases, based on their location on a chromosome.

Prader-Willi Syndrome: A condition characterized by obesity and insatiable appetite, mental deficiency, small genitals, and short stature. May be deletion of #15 chromosome.

Predisposition: To have a tendency or inclination towards something in advance.

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