 Chromosomes are coiled up “packages” of DNA.

 Listen to the following case study about Colin Pitchfork taken from “What is Life?” by Jay Phelan.

 When cell is about to divide, DNA coils up into CHROMOSOMES.  Each section or piece of the DNA – called a GENE- strand codes for a specific protein, that carries out a cellular function.  These chromosomes will double, or replicate, right before cell division.

 Each chromosome consists of 2 identical copies (the original chromosome and the replicated chromosome) called CHROMATIDS.  The 2 chromatids are connected at the point called the CENTROMERE.

 Each species has a specific number of chromosomes.  Organisms have 2 (a pair) of each chromosome (i.e. pair #1, #2, #3, etc).  Called HOMOLOGOUS CHROMOSOMES- chromosomes that cover the same information, but are different versions; one is inherited from mom and one is inherited from dad The two homologous chromosomes, one from “mom” and one from “dad”, together are referred to as a HOMOLOGOUS PAIR.