turnover rate the rate at which members of a population or community replace themselves
turpentine A solvent that includes two terpenes--camphor and pinene.
tusk shells Molluscs that have an elongate, tapered shell that is open at both ends.
Purines from turnover of nucleic acids (or from food) can also be salvaged and reused in new nucleotides.
Remodeling or bone turnover is the process of resorption followed by replacement of bone with little change in shape and occurs throughout a person's life.
Pericellular proteolysis represents one of the key modes by which the cell can modulate its environment, involving not only turnover of the extracellular matrix but also the regulation of cell membrane proteins, ...
Apoptosis: The genetically programmed death of cells at specific times during embryonic morphogenesis and development, metamorphosis, and during cell turnover in adults including the maturation of T and B cells of the immune system.
Through processes of paralogous recombination, these same regions are targets for rapid evolutionary turnover among the genomes of closely related primates.
destruction of "bad" mRNAs (e.g., those with premature STOP codons [see Nonsense-Mediated mRNA Decay (NMD)];
turnover of mRNAs thus increasing the flexibility of gene expression in the cell.
Exosomes ...
High-density lipoprotein (HDL) A lipoprotein that picks up cholesterol from dying cells and from membranes undergoing turnover, esterifies it, and then transfers the cholesterol esters to the liver and other steroid-synthesizing tissues.
Post-transcriptional regulation
Regulation of gene expression after the gene has been transcribed into mRNA. For example, by regulation of translation, regulation of protein activity, or regulation of protein turnover.
We know that the receptors, the proteins themselves that are modified, only last a few days, so they will actually turnover--that is, they will be broken down, degraded, and new ones will replace those receptors.
There is a rapid turnover of CD4+ T cells that ultimately leads to their destruction and to a change in lymphoid tissues that prevent immune responses. The figure is taken from Nature Medicine 9, 839 (2003) and is reproduced with permission.
Although less is understood about the mechanism of intermediate filament assembly and disassembly, it is clear that some classes are highly dynamic structures with a significant rate of turnover in many cell types.
 See also: Trans, Cells, Protein, Organ, Biology
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