Pedigree rules

Question 1

autosomal recessive

Answer 1

-both male and females
-skips generations
-affected offspring’s usually born to unaffected parents
-1/4 of offspring will be affected when both parents are heterozygous
-appears more frequently when parents are related

Question 2

autosomal dominant trait

Answer 2

-appear equally in males and females
-does not skip generations
-unaffected people do not transmit the trait
-affected people have at least one affected parent
-when one parent is affected (heterozygous) and the other parent is unaffected, approximately half of the offspring will be affected

Question 3

x linked recessive

Answer 3

-appear more often in males
-affected male cannot pass trait to son but can pass allele to daughter who is unaffected but can pass it to her sons who will be affected
-Classic hemophilia is inherited as an X-linked recessive
-trait skips generations
-all daughters of affect fathers are carriers, never passed from father to son

Question 4

x linked dominant

Answer 4

-do not skip generations
-affects both males and females
-affected males pass trait to all their daughters, none of their sons
-affected females (if heterozygous) pass the trait on to about half of their sons and half of their daughters
-often more females than males

Question 5

y linked

Answer 5

-appear only in males
-all male offspring’s are affected
-passed father to all son