Genetics: Quiz 4

Autosomal Traits vs. X-linked Traits

• Autosomal

  • traits come from genes on the 22 non-sex chromosomes and affect males and females equally

• X-linked

  • traits come from genes on the X chromosome and more often affect males because they only have one X

X-linked Dominant vs. X-linked Recessive

• X-linked Dominant

  • one mutated X chromosome causes the trait

  • all daughters are affected

  • less common than x-linked recessive

• X-linked Recessive

  • two mutated X chromosomes are needed for females, but only one mutated X is needed for males

  • daughters are usually carriers unless mom has the mutation

Autosomal Dominant vs. Autosomal Recessive

• Autosomal Dominant

  • a person only needs ONE copy of the mutation to be affected

  • trait often appears in every generation

  • males and females are affected equally

  • Ex)

    • AA = affected

    • Aa = affected

    • aa = not affected

• Autosomal Recessive

  • a person needs TWO copies of the mutation to be affected

  • parents are often healthy carriers

  • trait may skip generations

  • males and females are affected equally

  • Ex)

    • AA = unaffected

    • Aa = unaffected

    • aa = affected

What is this an example of?

a) x-linked dominant

b) x-linked recessive

c) autosomal dominant

d) autosomal recessive

a) x-linked dominant

Reason: father and all daughters are affected

What is this an example of?

a) x-linked dominant

b) x-linked recessive

c) autosomal dominant

d) autosomal recessive

b) x-linked recessive

Reason: mostly males are affected; trait skips generations

What is this an example of?

a) x-linked dominant

b) x-linked recessive

c) autosomal dominant

d) autosomal recessive

c) autosomal dominant

Reason: trait often appears in every generation; males and females are affected equally

What is this an example of?

a) x-linked dominant

b) x-linked recessive

c) autosomal dominant

d) autosomal recessive

d) autosomal recessive

Reason: parents are often health carriers; trait skipped a generation

What is the meaning of Epistasis?

Epistasis: one gene masks the effect of another gene

What are the four types of Epistasis and what are their ratios?

• Complementary Gene Action

  • 9:7 ratio

  • Need both genes working

• Recessive Epistasis

  • 9:3:4 ratio

  • Homozygous recessive masks another gene

• Dominant Epistasis

  • 12:3:1 ratio

  • Dominant allele masks another gene

• Duplicate Gene Action

  • 15:1 ratio

  • Either gene can make the other

Complementation vs Non-complementation

• Complementation

  • mutations occur in different genes

• Non-complementation

  • mutations occur in the same gene

What type of chromosome rearrangement is this?

a) deletion

b) inversion

c) duplication

d) translocation

a) deletion

What type of chromosome rearrangement is this?

a) deletion

b) inversion

c) duplication

d) translocation

b) inversion

What type of chromosome rearrangement is this?

a) deletion

b) inversion

c) duplication

d) translocation

d) translocation

What type of chromosome rearrangement is this?

a) deletion

b) inversion

c) duplication

d) translocation

b) duplication

Paracentric Inversion

• no centromere involvement

Pericentric Inversion

• involves centromere

What is the difference between reciprocal and non-reciprocal translocations?