Human Heredity Karyotype Karyotype a picture of chromosomes

Human Heredity Karyotype: Karyotype a picture of chromosomes lined up as homologous pairs

Human Chromosomes • Sex Chromosomes: Chromosomes the X and Y chromosomes determine whether or not an organism is a male or female (found in almost all animals) • Autosomes: Autosomes the remaining (non-sex) chromosomes • All human egg cells carry a single X chromosome. Half of sperm cells carry an X and half carry a Y.

Human Traits and Genes Human genes are inherited by the same principles that Mendel discovered in garden peas.

Pedigree • Chart—showing family relationships

Human genes • Blood groups • Dominant-Recessive AND Codominance – IA, IB, i – Blood type A: IAIA or IAi – Blood type B: IBIB or IBi – Blood type AB: IAIB – Blood type O: ii • Also Rh blood groups give the + or -; it takes two Rh- alleles to be negative

Recessive Alleles • Many human genes have become known through the study of genetic disorders • Recessive disorders: – PKU – Tay-Sachs – Cystic Fibrosis • Dominant disorders: – Huntington’s disease – Hypercholesterolemia • Codominant disorders: – Sickle Cell Disease

Gene…Molecule • In both cystic fibrosis and sickle cell disease, a small change in the DNA of a single gene affects the structure of a protein, causing a serious genetic disorder • CF is caused by a deletion of bases on chromosome #7 • Sickle cell disease is a result of abnormal hemoglobin which causes molecules to stick together and take on a sickle shape