Category: P

Neutrophils, eosinophils, and basophils are collectively known as polymorphonuclear granulocytes. This is due to the fact that collectively their nuclei are segmented into lobes and they have granule-like inclusions within their cytoplasm.  

A name applied to a condition in which a species of plant or animal is represented by several distinct, nonintegrating forms or types unrelated to age or sex. The differences are often in coloration, though any characteristic of the organism may be involved (e.g., nuclei shape for polymorphonuclear leukocytes). State of existing or occurring in…

Developed in 1984 and 1985 by Kary B. Mullis, Randall K. Saiki, Stephen J. Scharf, Fred A. Faloona, Glenn Horn, Henry A. Erlich, and Norman Arnheim, the PCR technique is an in vitro method that greatly amplifies (makes millions of copies of) DNA sequences that otherwise could not be detected or studied. It can be…

An “energy storage” substance that is naturally produced by certain bacteria, yeasts, and plants. When removed from the bacteria and purified, this substance has physical properties quite similar to thermoplastics like polystyrene. PHB can quickly be broken down by soil microorganisms, so PHB is a biodegradable plastic. Three separate enzymes are utilized by the organism…

An “energy storage” substance that is naturally produced by certain bacteria (90 strains known). When PHA is removed from the bacteria and purified, this substance has physical properties quite similar to thermoplastics like polystyrene. PHA can quickly be broken down by soil microorganisms, so PHA is a biodegradable plastic.  

A trait or end product (e.g., in a grain-produced crop) that requires simultaneous expression of more than one gene. For example, the level of protein produced in soybeans is controlled by five genes. Inheritance of an attribute whose expression is controlled by many genes or pairs. A trait that is expressed as a result of…

An enzyme (e.g., present in tomatoes) that starts the breakdown (softening) of the fruit tissue. Recent advances make it possible to significantly delay the softening (i.e., spoilage) process by reducing the production of polygalacturonase through genetic engineering of the plant. In 1 986, William Hiatt of the American company Calgene discovered the gene for polygalacturonase,…

Because a given pathogen generally has several antigenic sites on its surface, the B lymphocytes (activated by helper T cells in response to a pathogen invading the body) synthesize several (subtly different) antibodies against that pathogen. And since the antibodies are made by different cells the response is known as poly(many)clonal.    

A mixture of antibody molecules (that are specific for a given antigen) that has been purified from an immunized (to that given antigen) animal’s blood. Such antibodies are polyclonal in that they are the products of many different populations of antibody-producing cells (within the animal’s body). Hence they differ somewhat in their precise specificity and…

Coding regions representing more than one gene in mRNA (i.e., they code for two or more polypeptide chains). Many mRNA molecules in procaryotes are polycistronic.