Our Journey to Now: Outcome 10

What is the use of pedigree charts?

To show how an inheritance trait is passed through a family.

What is the symbol for females?

Circle

What is the symbol for males?

Square

What is the symbol for people without traits?

Unshaded

What is the symbol for people with traits?

Shaded

What is the symbol is someone has a recessive allele/is a carrier?

Half-shaded

How do you show the relation between a married couple?

Line connecting the midpoint of circle/square and circle/square

How many children does this couple have?

Two; both daughters

Are these people married?

No, they’re siblings

Who’s affected, who’s not, and who are characters?

Affected: Daughter

Not affected: Son

Carriers: Mother & Father

How are generations in a family pedigree numbered?

They are numbered using roman numerals, with the youngest generation being at the bottom.

How can we tell which siblings are the oldest in pedigrees?

Siblings are placed in birth order from left to right (oldest = far left, youngest = far right)

What does slashes through the symbols mean?

It means the person has died

Autosomal dominant

• Both parents are affected and offspring is unaffected - trait must be dominant (parents must be heterozygous)

• all affected individuals must have one effected parent

• If both parents are unaffected, all offspring must be unaffected (homozygous recessive)

Autosomal recessive

• If both parents are unaffected and the offspring is affected, the trait must be recessive, with the parents being heterozygous carriers

• If both parents show a trait then the offspring will show a trait (homozygous recessive)

X-linked dominant

• If a male shows a trait, all daughters as well as his mother must show the trait

• Unaffected mothers cannot have affected sons

• Tends to be more common in females

X-linked recessive

• If a female shows a trait, all the sons and her father must show the trait

• UNaffected mothers can have affected sons if she is a carrier (heterozygous)

• X-link recessive tend to be more common in males