PedigreesShow 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 Inheritancesee purple pages 15, 16

Modes of Inheritancesee purple pages 15, 16

Autosomal Recessive

Sex LinkedAutosomalDominant

•aa = affected•May skip 1 or moreGenerations (recessive trait hidden for generations)•2 unaffected may have affected•2 affected will have all children affected

•Aa or AA = affected•Affected need only have 1 affected parent•Affected (Aa) parents can have unaffected children (aa)

•Males mostly affected•Males inherit sex-linked trait from mothers •Girls must haveaffected fathers

Recessive?Dominant?Sex-linked?

AlbinismMust be autosomal recessive. For this condition, affected individuals are homozygous recessive – lack enzyme to produce melanin.

Pedigree Analysis

What is

thispedigreeshowing?

Why is inbreeding not recommended?

Chance ofrecessivecondition

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

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 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