genetics advanced

Complete dominznce

• A > a

• Aa → dominant trait

• When phenotypes of the heterozygote & dominant homozygote are identical.

Incomplete dominance

• hetero : blend → paint

• red x white → pink

• phenotype → blend of both traits

Co dominance

• hetero : both appear

  • type A x type B → AB

• Two dominant alleles affect the phenotype in separate, distinguishable ways

• allele 1 = allele 2

New trait appears : incomplete dominance

blend of both : co dominance

• set up as trait ^allele

lethal alleles - miscarriage

• either:

  • die before/at birth

  • survive

• persion that is heterozyguous for the disease is a

• dominant allele - affects person after reproductive age

XX

• same

  • AA, Aa aa

XY

• no masking

  • A or a (X^AY or X^aY)

Y - sex determining region

• development of testes

Human males - contain ony one X chromosome (one allele)

• known as hemizygous for X-linked traits

Human females - can be homozygous or heterozygous

• only females can be carriers (heterozygote for a recessive deseasse condition)

Hemophilia - blood clo

X^HX^H or X^HX^h : norma

X^hX^h - hemophilia

X^HXY: normal

X^hY: hemo

• Daughters are carries, do not suffer from disorder but can pass it on to sons

Polygenic ingheritence

• two or more genes on a single phenotype

• height have over 180 genes affecting it

Pedigrees - chart of genetic history of a family over several generations

• males - squares, females - circles

Autosomal dominant - cannot be recessive bc two affected parenys cant have unaffected offspring

• parents - heterozygous

Autosomal recessive - cannot be dominant bc two unaffected parents cannot have affected offspring

• parents - homozygous