Structural inheritance
Encyclopedia
Structural inheritance or cortical inheritance is the transmission of a trait in a living organism
by a self-perpetuating spatial structures. This is in contrast to the transmission of digital information such as is found in DNA
sequences, which accounts for the vast majority of known genetic
variation.
Examples of structural inheritance include the propagation of prion
s, the infectious proteins of diseases such as scrapie
(in sheep and goats), bovine spongiform encephalopathy
('mad cow disease') and Creutzfeld-Jakob disease (although the protein-only hypothesis of prion transmission has been considered contentious until recently.) Prions based on heritable protein structure also exist in yeast
. Structural inheritance has also been seen in the orientation of cilia
in protozoans such as Paramecium
and Tetrahymena
, and 'handedness' of the spiral of the cell in Tetrahymena, and shells of snails. Some organelle
s also have structural inheritance, such as the centriole
, and the cell
itself (defined by the plasma membrane) may also be an example of structural inheritance.
Various additional examples of structural inheritance are presented in the recent book Origination of Organismal Form
.
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
by a self-perpetuating spatial structures. This is in contrast to the transmission of digital information such as is found in DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
sequences, which accounts for the vast majority of known genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
variation.
Examples of structural inheritance include the propagation of prion
Prion
A prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...
s, the infectious proteins of diseases such as scrapie
Scrapie
Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies , which are related to bovine spongiform encephalopathy and chronic wasting disease of deer. Like other spongiform encephalopathies, scrapie...
(in sheep and goats), bovine spongiform encephalopathy
Bovine spongiform encephalopathy
Bovine spongiform encephalopathy , commonly known as mad-cow disease, is a fatal neurodegenerative disease in cattle that causes a spongy degeneration in the brain and spinal cord. BSE has a long incubation period, about 30 months to 8 years, usually affecting adult cattle at a peak age onset of...
('mad cow disease') and Creutzfeld-Jakob disease (although the protein-only hypothesis of prion transmission has been considered contentious until recently.) Prions based on heritable protein structure also exist in yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
. Structural inheritance has also been seen in the orientation of cilia
Cilium
A cilium is an organelle found in eukaryotic cells. Cilia are slender protuberances that project from the much larger cell body....
in protozoans such as Paramecium
Paramecium
Paramecium is a group of unicellular ciliate protozoa, which are commonly studied as a representative of the ciliate group, and range from about 0.05 to 0.35 mm in length. Simple cilia cover the body, which allow the cell to move with a synchronous motion at speeds of approximately 12 body...
and Tetrahymena
Tetrahymena
Tetrahymena are free-living ciliate protozoa that can also switch from commensalistic to pathogenic modes of survival. They are common in fresh-water. Tetrahymena species used as model organisms in biomedical research are T. thermophila and T. pyriformis.- T...
, and 'handedness' of the spiral of the cell in Tetrahymena, and shells of snails. Some organelle
Organelle
In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....
s also have structural inheritance, such as the centriole
Centriole
A Centriole is a barrel-shaped cell structure found in most animal eukaryotic cells, though it is absent in higher plants and most fungi. The walls of each centriole are usually composed of nine triplets of microtubules...
, and the cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
itself (defined by the plasma membrane) may also be an example of structural inheritance.
Various additional examples of structural inheritance are presented in the recent book Origination of Organismal Form
Origination of Organismal Form
Origination of Organismal Form: Beyond the Gene in Developmental and Evolutionary Biology is a book published in 2003 edited by Gerd B. Müller and Stuart A. Newman. It explores the multiple factors that may have been responsible for the origination of biological form in multicellular life...
.