Welcome 2/10-11/16 1. Turn in Quick Lab and Dihybrid Cross 2. Other Mendelian Genetics and Disorders Notes 3. Practice Non-Mendelian Genetics

{ Other Mendelian Genetics, Karytoypes, and Genetic Disorders

Other Patterns of Inheritance

Incomplete Dominance Some alleles are neither dominant nor recessive. Some alleles are neither dominant nor recessive. Incomplete dominance: One allele is not completely dominant over another. Incomplete dominance: One allele is not completely dominant over another.

Codominance The phenotypes for both alleles are clearly expressed. The phenotypes for both alleles are clearly expressed. Examples: chicken feather color, human protein controlling blood cholesterol levels Examples: chicken feather color, human protein controlling blood cholesterol levels

Multiple Alleles Many genes exist in more than two forms. Many genes exist in more than two forms. Examples: human blood types, fur color in rabbits Examples: human blood types, fur color in rabbits

Polygenic Traits Many traits are produced by the interaction of several genes. Many traits are produced by the interaction of several genes. Examples: eye color in fruit flies, coat color in dogs Examples: eye color in fruit flies, coat color in dogs Traits typically show a wide variety of phenotypes. Traits typically show a wide variety of phenotypes.

Genes and the Environment Environmental conditions can affect gene expression and influence genetically determined traits. The of an organism is only partly determined by its. phenotype genotype

Genetics Disorders

 Phenotypic expression on the trait dominantly  Ex: B = Brown (dominant), b = blue (recessive)  BB = Brown  Bb = Brown  bb = Blue  Dominant only require 1 mutant gene of the pair of chromosome to be affected  Recessive required 2 mutant genes to be affected Dominant vs. Recessive

Sex-linked diseases are inherited through one of the sex chromosomes (the X or Y chromosome).  Female XX  Male XY Sex-linked

 Autosomal diseases are inherited through other chromosomes rather than sex-chromosomes. Autosomal

 Sex-linked dominant = mutation on 1 of the pair of sex chromosome. (XX, XY, XY)  Abnormal gene dominated the gene pair  Sex-linked recessive = mutation on 2 sex chromosomes (XX or XY)  Abnormal gene on both sex chromosomes to be affected  One abnormal gene and one normal gene is not affected but carried Sex-linked Dominant vs. Sex-linked Recessive

Example of Sex-linked Trait Inheritance

 Using a Punnet square to cross a female who carries a recessive disease on one of her X chromosome and her husband is normal.  Is this Autosomal or Sex-linked?  Dominant or recessive?  How will this affect her children?  How many percent of her children are likely to be affected? Example

{ Inheritance of Traits: Pedigrees and Genetic Disorders

 Pedigree: a family history that shows how a trait is inherited over several generations  Pedigrees are usually used when parents want to know if they are carriers of a particular disorder Pedigree definition

 Female  Male  Married Couple  Siblings Making a Pedigree Filled in symbols indicate individual is affected with a disorder

Example of a Pedigree You Parents Aunts, Uncles Grandparents Brother Do any disorders run in this family??

 What can you tell from a pedigree?  Whether a family has an autosomal or sex-linked disease or disorder  Autosomal disorder: appears in both sexes equally  Sex-linked disorder: allele is located only on the X or Y chromosome. Most sex-linked genes are on the X chromosome and are recessive  So who would have an X-linked disorder more often, boys or girls?  Whether a disorder is dominant or recessive Interpreting a Pedigree

Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? You Parents Aunts, Uncles Grandparents Brother Sex Linked! (in this case allele is recessive and located on the X chromosome)

Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? You Parents Aunts, Uncles Grandparents Brother Autosomal dominant!

Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? You Parents Aunts, Uncles Grandparents Brother Autosomal recessive!

 Color blindness  Sickle cell anemia  Cystic Fibrosis  Hemophilia  Huntington’s Disease Common Genetic Disorders For more info, go to:

Color Blindness  Deficiency to percieve colors  Problem with color- sensing pigments in certain nerve cells of the eye  About 1 in 10 men have some form of color blindness.  Sex-linked disorder

Sickle Cell Anemia  Disorder where abnormal hemoglobin (a protein inside red blood cells) is produced and warps red blood cells  Sickle cells deliver less oxygen to body’s tissues and can get stuck in small blood vessels  Recessive trait, tends to be seen in people of African or Mediterranean descent

 Recessive, autosomal disease  Life threatening, causes thick mucus to build up in various areas of the body (lungs, digestive tract, etc).  Tends to run in Caucasians, of Northern/Central European descent (1 in 29 Americans (1 in 29 Americans carry the allele) carry the allele)  Average life span in US for people with CF is 37, death usually caused by lung complications Cystic Fibrosis

 Bleeding disorder, where it takes a long time for blood to clot (body lacks proteins involved in clotting)  Sex-linked (carried on the X chromosome)  Treatment involves injection with missing clotting protein Hemophilia

 Autosomal, dominant  Deterioration of brain tissue, usually begins between age 30 and 40.  No cure, but have medications to cope with symptoms  People usually die years after onset of degeneration Huntington’s Disease