Pedigrees
Pedigrees Show how traits are passed on in a family Female Male = = See purple booklet after page 16 OR blue page 57 for pedigree symbols (these are on your diploma exam data sheet). Line down from a horizontal line indicates offspring. Oldest offspring always on the left Affected individuals are shaded in Heterozygous individuals half shaded in (sometimes)
Modes of Inheritance see purple pages 15, 16 Autosomal Recessive Autosomal Dominant Sex Linked Males mostly affected Males inherit sex-linked trait from mothers Girls must have affected fathers Aa or AA = affected Affected need only have 1 affected parent Affected (Aa) parents can have unaffected children (aa) aa = affected May skip 1 or more Generations (recessive trait hidden for generations) 2 unaffected may have affected 2 affected will have all children affected for more details see - Blue booklet: pages 54, 55
Albinism Recessive? Dominant? Sex-linked? not dominant Must be autosomal recessive. For this condition, affected individuals are homozygous recessive – lack enzyme to produce melanin. HINT: what do these symbols mean? Recessive? Dominant? Sex-linked?
Pedigree Analysis What is this pedigree showing?
Why is inbreeding not recommended? Chance of recessive condition showing up in offspring is increased!
Lets’ draw a pedigree for Jason’s family Sister (28) – unaffected Jason (27) - unaffected Brother (25) – affected Identical twin brothers (18) – unaffected Mother (46) – unaffected Father (45) – affected Paternal sister (43) – affected Paternal grandmother (77) – unaffected Paternal grandfather (79) - affected Jason
Pedigree Questions All pedigree questions: Today Go to…purple - after page 16 – page 2 (Tay-Sachs disease)… orange page 48 – 50 Together: start page 51… All pedigree questions: Purple: page 2 – 5 (after page 16) Orange: pages 48 - 55 Blue: page 33 – 36
All pedigree questions: Purple: page 2 – 5 (after page 16) All X-linked Questions: Orange: pages 36 – 41 Blue: page 48 All pedigree questions: Purple: page 2 – 5 (after page 16) Orange: pages 48 - 55 Blue: page 33 – 36 Pedigree sheet