PEDIGREE CHARTS & KARYOTYPES Unit 6, Part 4 Notes

What is a pedigree chart? Pedigree charts are graphics of families that show how a trait is passed through a family. They can be used to study passing of a particular trait through a family.

Symbols used in pedigree charts Normal male Affected male Normal female Affected female Marriage Carrier Carrier- a person has one allele for a particular trait but does not have the trait expressed in the phenotype. A marriage with five children, two daughters and three sons. The middle son is affected by the condition. Eldest child  Youngest child

Organizing the pedigree chart Generations are identified by Roman numerals I II III IV

Organizing the pedigree chart Individuals in each generation are identified by Arabic numerals numbered from the left Therefore the affected individuals are II3, IV2 and IV3 I II III IV

Karyotypes A chart composed of an individual’s paired chromosomes. Used to identify if an individual has an unusual number of chromsomes.

Changes in Chromosome # Monosomy- Having only 1 chromosome in a pair instead of two. Turner Syndrome Only 1 X-chromosome Missing an X-chromsome on pair #23 Trisomy- Having an extra chromosome (3 instead of 2. Down Syndrome Extra chromosome on pair #21 Klinefelter’s Syndrome Have an extra X-chromosome Genotype=XXY Polyploidy- Having more than one extra chromosome in a pair.

Normal Male 9 2n = 46

Normal Female 10 2n = 46

Male, Trisomy 21 (Down’s) 11 2n = 47

Turner Syndrome 12 2n = 47