Chapter14: Human Heredity

Making a Pedigree Pedigree –A graphic representation of genetic inheritance. –Track genotypes by looking at their phenotypes –Genotype- allele combination for genes that express a trait (ex. AA, Aa, aa) –Phenotype- physical traits caused by a genotype( ex. AA= red flowers, aa= white flowers Carrier- person who can pass on a disease but it not effected by it

Reading a Pedigree Is this a dominate or recessive disease? Which individuals MUST be carriers? I-1,2; II-1 or 2; III- 3,4 What are the possible genotypes for III-1? AA or Aa Aa aa Aa aa Recessive (aa) AA or Aa

Reading a Pedigree Is this a dominate or recessive disease? Which individuals MUST be carriers? -None. Cannot have carries for a simple dominate disease What are the possible genotypes for IV-1? -AA or Aa aa AA or Aa aa AA or Aa Dominate (AA, Aa) aa

Recessive traits can remain dormant and can appear suddenly; carriers Tend to skip generations Some recessive disease are fatal and have late onset; disease starts when you are an adult Simple Recessive Heredity

Cystic fibrosis disease 1/28 Americans are carriers –Thick mucus builds in the lungs –Makes physical activity difficult –Must be treated with medication

Simple Recessive Heredity Phenylketonuria (PKU) –Body lacks enzyme to change phenylalanine to tyrosine –Build up in the body leads to a damaged nervous system –Fetuses are tested to treat with diet

Simple Dominant Heredity Heredity of many physical characteristics –Widow’s peak hairline –Darwin earlobes –Hitchhiker’s thumb Traits appear in every generation and is equally spread between males and females

Complex Patterns of Inheritance Multiple phenotypes from multiple alleles Traits controlled by more than two alleles have multiple alleles Blood Type  I A, I B, or I, different combinations make blood types

Complex Patterns of Inheritance Polygenic inheritance –Polygenic inheritance is the inheritance pattern of a trait that is controlled by two or more genes. –Alleles are not dominate or recessive; they represent degrees of expression –All heterozygotes are intermediate in phenotype.

Complex Patterns of Inheritance Sex determination : –chromosomes, which determine the sex of an individual, are called sex chromosomes. –All other chromosomes are called autosomal chromosomes.

Complex Patterns of Inheritance Sex-linked inheritance

W+W+W+W+ WW WW + WW? Results not possible using Mendel…

Genes linked to X and Y Chromosomes

Complex Patterns of Inheritance Sex-linked traits: Traits controlled by genes located on sex chromosomes are called sex-linked traits. –Red-green color blindness –Hemophilia

Complex Patterns of Inheritance X Chromosome Inactivation –Females only need one X chromosome to survive –Inside each cell of a female, one of the two X chromosomes are randomly deactivated (barr body) –Females Calico Cats  random colors

Complex Patterns of Inheritance Environmental Factors:Environmental Factors: –Temperature, nutrition, light, etc… can effect the phenotype of an individual by changing the expression of the genes –Ex. Arctic Fox Internal Factors:Internal Factors: –Hormones regulate gene expression so a genotype may not express the same phenotype it different individuals –Ex. Peacocks

Human Genetic Disease Presentations Next Week: PPTs in groups of 4Next Week: PPTs in groups of 4 –Select a genetic disease from the list today –NO LONGER THAN 10 MINUTES!!! –Tell explain the following: What causes the disease?What causes the disease? What are the symptoms?What are the symptoms? How common is the disease?How common is the disease? How can the disease be treated?How can the disease be treated? Disease to Pick: 1)Angelman Syndrome 2) Cri du chat 3) Down Syndrome 4) Neurofibromitosis 5) Prader-Wili Syndrome 6) Tay-Sachs Disease 7) Turner Syndrome 8) Albinism 9) Canavan Disease 10) Haemochromatosis