Ch. 11 Complex Heredity

11.2 Complex Patterns of Inheritance

• These do not follow the same patterns discussed by Mendel• Ex.

• Incomplete dominance – the heterozygous phenotype is an intermediate phenotype between 2 homozygous phenotypes.• Aka - blending• Draw & show self-fertilization of F1

•Codominance – both alleles are expressed in the heterozygous condition.• Ex. Sickle cell disease

• This person is heterozygous for sickle cell disease.• Has both normal red blood cells

& sickle cells• Does not transport Oxygen as well• If hetero - can still lead a normal life

• Malaria - Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells.

• Symptoms of malaria include fever, headache, and vomiting, and usually appear between 10 and 15 days after the mosquito bite. If not treated, malaria can quickly become life-threatening by disrupting the blood supply to vital organs. In many parts of the world, the parasites have developed resistance to a number of malaria medicines.

• Shade next picture – p.303

• Multiple alleles – some forms of inheritance are marked by more than 2 types of alleles• Ex. Blood type

• ABO blood groups have 3 forms of alleles (AB markers)

• IA, IB, I (on board) p304• Universal donor: O• Universal acceptor:AB

• Rh Factor: blood protein (+ has the protein)• Either + or –• + is dominant 85% of population

• Blood type Percent of Americans with this type Who can receive this type

• O+ 37% B+ 10%• O– 6 B- 2%• A+ 34 AB+ 2%• A– 6• AB– 1

• Cross a parent with heterozygous A with AB (2 factor cross)

Sex chromosomes

• Humans have 23 pair of chromosomes• 22 are called autosomes• 1 pair are the sex chromosomes

• XX = female• XY = male

• Draw punnet square p. 305

Sex – linked traits

•Traits controlled by genes located on the X chromosome are called sex-linked traits

• Ex. Color blindness• P307 draw punnet square