February 2 2016 Bell Work What does heterozygous
February 2, 2016 Bell Work: • What does heterozygous mean? Objective: The student will be able to…
Today in History • 1536 The Argentine city of Buenos Aires was founded. • 1848 The Treaty of Guadalupe Hidalgo was signed, ending the Mexican War.
Pedigree
Inheritance of Traits • A pedigree is a family history that shows how a trait is inherited over several generations • Pedigrees are particularly helpful in tracing genetic disorders • Carriers are individuals who are heterozygous for the disorder, but do not show symptoms
Inheritance of Genes • If a gene is autosomal, it will appear in both sexes equally • Autosomal: a chromosome other than the X or Y chromosome • If a gene is sex-linked, its effects are only seen in males • A sex-linked gene’s allele is located only on the X or Y chromosome
Inheritance of Genes • If a male (XY) carries a recessive allele on the X chromosome will exhibit the sex linked condition • A female (XX) will only express the recessive condition if she inherits two recessive alleles • Chance of inheriting and exhibiting a sexlinked condition is significantly less
Inheritance of Genes • If the gene is autosomal dominant, every individual with the condition will have a parent with the condition • If the condition is recessive an individual with the condition can have one, two, or neither parent exhibit the condition
Inheritance of Genes • Two people who are heterozygous carriers of a recessive mutation will not show the mutation, but they can produce children who are homozygous for the recessive allele.
Complex Patterns of Heredity • Polygenic Inheritance is when several genes influence a character • May be scattered along the same chromosome or located on different chromosomes • (Human) Examples include: eye color, height, weight, hair color, skin color • All these characters have degrees of intermediate conditions between one extreme and the other
Complex Patterns of Heredity • Incomplete dominance is where an organism displays a phenotype that is intermediate between two parents • Incomplete dominance: a condition in which a trait in an individual is intermediate between the phenotype of the individual’s two parents because the dominant allele is unable to express itself fully
Complex Patterns of Heredity • Multiple alleles are when genes have three or more alleles • Example: Blood Type (ABO system) • Codominance is when both forms of the character are displayed • Example: Blood Type (ABO system)
Environmental Factors • An individual’s phenotype often depends on the conditions in the environment • Example: Hydrangeas • Blue when planted in acidic soil • Pink when in neutral or basic soil • Example: Arctic Fox • During the summer the fur produces pigments resulting in dark fur • During the winter the pigment producing genes do not function because of the cold temperature, resulting in white fur
Environmental Factors • Example: Humans • Height: influenced by nutrition • Skin color: influenced by exposure to the sun
Genetic Disorders • Harmful effects produced by inherited mutations are called genetic disorders • Many are carried by recessive alleles • Examples include: • Sickle Cell Anemia • Cystic Fibrosis • Hemophilia • Huntington’s Disease
Treating Genetic Disorders • Gene therapy • Correcting genetic disorders by replacing defective genes with copies of healthy ones • Current attempts in humans have not been successful, but gene therapy is the best prospect for treating and curing genetic disorders.
Genetics Lab How to Create a Dragon Part #1
Ticket Out • Can environmental factors affect genetics?
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