Glossary of Scientific Terms

N

Nanotechnology
A technology that creates small materials at the scale of molecules by manipulating single atoms. The name nano comes from the size of molecules which is measured in nanometers - or one billionth of a meter (0.000000001 meter). The dimension of single atoms is ten fold smaller. The molecular processes of life, particularly the activity of proteins (enzymes) and the self-organizing behavior of many biological molecules has greatly inspired nanotechnology and molecular motors (i.e. protein complexes) could be considered the result of natures nanotechnology.

Natural selection
The process described by Darwin's theory of evolution that favors certain genotypes and disfavors others. This process is entirely guided by the interaction of an organism with its environment. See also adaptation.

Neurotransmitter
A chemical substance released from neurons in synapses that binds to corresponding receptors on nearby cell surfaces (post synaptic membrane) causing a physiological stimulus in form of a membrane current (triggering action potentials) or second messenger cascade activating channels, pumps, kinases, or proteases. The molecular mechanisms of activation are similar to those of hormones.

Nucleic acid
The collective name for DNA and RNA molecules found in every cell. The genetic component of cells (DNA, RNA polymers), but also important for cellular energy metabolism, signaling, and protein biosynthesis (RNA, single nucleotides).

Nucleus
An organelle in eukaryotic cells. It forms a membrane compartment containing most of the genetic material (DNA and RNA) of a eukaryotic cell (residual extra-nuclear genes are found in mitochondria and chloroplasts). A double membrane envelope separates the genetic material (chromosomes) from the cytoplasmic compartment. Nuclear pores allow for the exchange of proteins and RNA, but not chromosomes, during gene regulation and expression. The nuclear compartment separates the processes of transcription (messengar RNA formation) from translation (protein biosynthesis).

Nutraceuticals
Chemicals that have beneficial effects (pharmacological effects) on our physiology if taken in appropriate amounts with food. Plants are the major source of nutraceuticals also known as phytochemicals. Plants produce those molecules for self-defense or to attract insects and animals to facilitate pollen distribution. For the latter purpose, they often are colorants while tasting bitter to ward of animals.

Nutrient
Molecules that can be used by cells or living organism to extract energy through metabolic processes. Although nutrients are often sought off only as energy providers, they can also be used as molecular building block for the biosynthesis of cellular structures.