Locus
The field of genetics allows scientists to determine how an organism is able to inherit some of its characteristics from its ancestors, for example; how children inherit certain aspects of their features, such as hair colour, or facial features such as a big nose or ears, from a parent. These characteristics are often called ‘traits’ and can include anything from physical features to types of behaviour.
Sometimes the child's environment can modify traits, and the interaction of the child’s inherited characteristics and the environment can combine to change the appearance of an individual, say for example, if they live an area where food is scarce, they may not grow as expected. This can also be demonstrated by the fact that some illnesses, such as cancers and heart disease can be determined, not only be inherited traits, but by the lifestyle of the individual. A long molecule called DNA carries information about every single human, and the traits from an individual are carried in small segments called genes, which are combined to produce a code.
Within DNA are found many chromosomes which are single strands of coiled DNA, which themselves contain many different segments of information which then combine to produce cells. Any fixed point on a chromosome is called a locus. This acts almost as an address label for a specific piece of chromosome where a gene can be found, and works as a bio-marker, which allows scientists to map a specific section of a gene. It could, for example, specify that the twentieth gene on chromosome four will give you a gene for brown eyes. The plural for locus is loci.
