The cards in this area of the stack contain many common words found in the study of genetics. Where appropriate, they are supported by drawings.
A fundamental unit in genetics is the
GENE
A segment of nucleic acid responsible for producing an inherited trait. It can be defined in various ways. In classical Mendelian Genetics it was viewed as a structural unit of the chromosome. It can also be defined as a unit of mutation or crossing over. Both of these definitions reduce the gene to a single base pair in the chromosome. However it has also been functionally defined as a unit of nucleic acid that produces an inherited phenotypic effect... a visual sign or a chemical capacity. As such, the latter definition requires the gene to consist of at least several score nucleotides in a linear sequence. However it is defined, the genes are aligned in a linear sequence along the length of a chromosome. Scroll down the window for the definition of a chromosome.
CHROMOSOME
A macromolecular organelle consisting of DNA and associated proteins on which genetic information is encoded in the form of genes. In the schematic diagram at the right, a chromosome is shown with a linear arrangement of genes. Note that the genes are depicted via different patterns to emphasize the fact that they control different genetic characteristics.
CENTROMERE
A slightly constricted portion of the chromosome at which the spindle fibers attach during either mitosis or meiosis. For more definitions, flip to the next card.
