Integrative Levels of Organization Structure the field of Genetics.

The integrative levels most relevant to genetics cover the spectrum from macromolecules through populations.   Changes in macromolecules can have major effects on biochemical interactions, cellular function, the appearance and behavior of an organism and can even effect the structure of  populations.       

Dimensions of Analysis: Each integrative level must be studied with tools available for that level.  Changes at any one level must be related to changes at all higher levels. For example, a very small mutation in the macromolecule of DNA  might lead to a devastating illness such as cystic fibrosis (CF) in human (organism level).

 Understanding a disease phenotype like CF requires study of the changes at many different integrative levels using the appropriate methodology.  Molecular techniques, histology, physiology, biochemistry, etc are all aspect of genetics.

Phenotypes must always be defined according to the integrative level under consideration. The inheritance pattern (e.g., dominance) of an allele is an emergent property.    As one moves through the integrative levels the effect of an allele will change.

Review of Integrative Levels

 1.

Matter arrayed in the order of increasing complexity.

 2.

The hierarchy spans subatomic particles to atoms, atoms form molecules, and molecules form macromolecules ( DNA, RNA, Proteins).  From here we get other levels such as

 cells> tissues>organs>organ systems> organisms ->populations ->biospheres >??

A.

Integrative levels rest on a physical foundation.  The lowest physical level seems to be subatomic particles.  For the purposes of genetics the lowest integrative levels of interest are molecules and macromolecules. 

B.

At each level there occur emergent properties.   Emergent properties are not predictable even if you have complete knowledge of the lower levels. 

C.

The mechanism(s) underlying a phenotype is found at the level below.  The "purpose" or effect of phenotype is found at the level above.

D.

Knowledge of the lower levels of organization aid understanding of higher levels of organization.  Understanding the emergent properties of a higher level do not  inform one about the properties of lower levels. 

E.

The higher the integrative level the more complex it is. That is, the higher levels may show more variation and more characteristics. 

G.

A disturbance introduced  in any level (such as a mutation in DNA) affects all higher levels of organization.  The effect of such a perturbation may be severe or trivial.