Similarity in the sequence of a protein or nucleic acid or in the structure of an organ that reflects a common evolutionary origin. Molecules or sequences that exhibit homology are referred to as homologs. In contrast, analogy is a similarity in structure or function that does not reflect a common evolutionary origin.
The eukaryotic organelle containing DNA together with transcriptional machinery. DNA is organized into chromosomes. Prior to cell division chromosomes are replicated and then condense, at which time the nuclear membrane breaks down.