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Illustration of an activator. In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. [ 1 ][ 2 ] The function of TFs is to regulate—turn on and off—genes in order ...
v. t. e. The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleotide sequences for DNA, RNA, or amino acid sequences for proteins.
A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as genocide, speciocide, widespread violence or intentional culling. Such events can reduce the variation in the gene pool of a ...
Solitary predator: a polar bear feeds on a bearded seal it has killed. Social predators: meat ants cooperate to feed on a cicada far larger than themselves. Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes ...
Scanning electron micrograph of HIV-1, colored green, budding from a cultured lymphocyte. HIV is the cause of the spectrum of disease known as HIV/AIDS. HIV is a retrovirus that primarily infects components of the human immune system such as CD4 + T cells, macrophages and dendritic cells. It directly and indirectly destroys CD4 + T cells.
See also: Reprogramming. A scheme of the generation of induced pluripotent stem (IPS) cells. (1) Isolate and culture donor cells. (2) Transduce stem cell-associated genes into the cells by viral vectors. Red cells indicate the cells expressing the exogenous genes. (3) Harvest and culture the cells according to ES cell culture, using mitotically ...
The pharmacological definition cannot apply to these substances because utilization and absorption is a function of the nutritional status and physiological state of the subject, [10] resulting in even greater differences from individual to individual (inter-individual variation). Therefore, bioavailability for dietary supplements can be ...
Factor V. Coagulation factor V (Factor V), also less commonly known as proaccelerin or labile factor, is a protein involved in coagulation, encoded, in humans, by F5 gene. [5] In contrast to most other coagulation factors, it is not enzymatically active but functions as a cofactor. [5] Factor V deficiency leads to predisposition for hemorrhage ...