Mathematics and Society - OS X Lion Server

The physical traits that an individual has are inherited from his parents. Traitsare determined by a combination of gene groups--one gene group coming from each parent.Eye color can be used as an example. Each parent possesses a gene group with two partscalled alleles that are related to eye color. Biologists use an upper case B to indicatethe allele for brown eyes and a lower case b for the allele for blue eyes. For eyecolor the B allele is dominant over the b allele, so a combination bf Bb will producebrown eyes. The following shows the possible allele combinations and the color of eyesthat will be produced.BBbrown eyesbbblu.eevesBbbrown eyesbBbrown evesThese last two (Bb and bB) indicate the same combination. Biologists usually writethe upper case letter first. BB and bb are called pure combinations because both allelesof the combination are the same. Bb is called a hybrid combination.The combinations that are possible are often shown by using a grid.example one parent has pure brown eyes and the other has pure blue eyes.For this firstPURl::BBROWtVBb Bb Bb ALL OFFSPRllJG WILL HAVE Bb COMBIr.JATIOIJ \tJ>lICHPURt: BLUE. PRODUCES BROWI\) EVES.b Bb BbNow consider two 'parents with hybrid brown eyes.163