Complex Inheritance and Human Heredity Cystic Fibrosis  Affects the mucus-producing glands, digestive enzymes, and sweat glands  Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in the sweat.  Without sufficient chloride ions in the cells, a thick mucus is secreted Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity Albinism  Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes  White hair  Very pale skin  Pink pupils 11.1 Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity Tay-Sachs Disease  Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides  Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity Galactosemia  Recessive genetic disorder characterized by the inability of the body to digest galactose Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity Dominant Genetic Disorders  Huntington’s disease affects the nervous system.  Achondroplasia is a genetic condition that causes small body size and limbs that are comparatively short Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity Pedigrees  A diagram that traces the inheritance of a particular trait through several generations 11.1 Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity Inferring Genotypes  Knowing physical traits can determine what genes an individual is most likely to have. Predicting Disorders  Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes Basic Patterns of Human Inheritance Chapter 11

11.2 Complex Patterns of Inheritance Complex Inheritance and Human Heredity Incomplete Dominance  The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes. Chapter 11

Complex Inheritance and Human Heredity Codominance  Both alleles are expressed in the heterozygous condition Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Sickle-cell Disease  Changes in hemoglobin cause red blood cells to change to a sickle shape.  People who are heterozygous for the trait have both normal and sickle-shaped cells. Sickle cell Normal red blood cell 7766x 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Multiple Alleles  Blood groups in humans  ABO blood groups have three forms of alleles Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Coat Color of Rabbits  Multiple alleles can demonstrate a hierarchy of dominance.  In rabbits, four alleles code for coat color: C, c ch, c h, and c Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Coat Color of Rabbits Light gray Dark gray Himalayan Albino Chinchilla 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Epistasis  Variety is the result of one allele hiding the effects of another allele. No dark pigment present in fur Dark pigment present in fur eebb eeB_ E_bbE_B_ 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Sex Determination  Sex chromosomes determine an individual’s gender Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Sex-Linked Traits  Genes located on the X chromosome  Red-green color blindness  Hemophilia 11.2 Complex Patterns of Inheritance Chapter 11 Sex-Linked Traits

Complex Inheritance and Human Heredity Polygenic Traits  Polygenic traits arise from the interaction of multiple pairs of genes Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Environmental Influences  Environmental factors  Diet and exercise  Sunlight and water  Temperature 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Twin Studies  Helps scientists separate genetic contributions from environmental contributions  Traits that appear frequently in identical twins are at least partially controlled by heredity.  Traits expressed differently in identical twins are strongly influenced by environment Complex Patterns of Inheritance Chapter 11

 Karyotype—micrograph in which the pairs of homologous chromosomes are arranged in decreasing size Chromosomes and Human Heredity Complex Inheritance and Human Heredity Karyotype Studies  Images of chromosomes stained during metaphase  Chromosomes are arranged in decreasing size to produce a micrograph. Chapter 11