Biology Chapter 11 Powerpoint

Biology Chapter 11 Powerpoint - Chapter 11 Mendelian...

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Unformatted text preview: Chapter 11 Mendelian Inherita 2 Mendelian Inherita Outline Blending Inheritance Monohybrid Cross Law of Segregation Modern Genetics Genotype vs. Phenotype Punnett Square Dihybrid Cross Law of Independent Assortment Human Genetic Disorders 3 Mendelian Inherita Gregor Mendel Austrian monk Studied science and mathematics at Studied University of Vienna University Conducted breeding experiments with the Conducted garden pea Pisum sativum Pisum Carefully gathered and documented Carefully mathematical data from his experiments mathematical Formulated fundamental laws of heredity in Formulated early 1860s early Had no knowledge of cells or chromosomes Did not have a microscope Gregor Mendel 4 Fruit and Flower of the Garden Pea 5 Garden Pea Traits Studied by Mendel 6 7 Mendelian Inherita Blending Inheritance Theories of inheritance in Mendel’s time: Based on blending Parents of contrasting appearance produce Parents offspring of intermediate appearance offspring Mendel’s findings were in contrast with this He formulated the particulate theory of He inheritance inheritance Inheritance involves reshuffling of genes from Inheritance generation to generation generation 8 Mendelian Inherita One-Trait Inheritance Mendel performed cross-breeding Mendel experiments experiments Used “true-breeding” (homozygous) plants Chose varieties that differed in only one trait Chose (monohybrid cross) (monohybrid Performed reciprocal crosses ­ Parental generation = P ­ First filial generation offspring = F1 ­ Second filial generation offspring = F2 Formulated the Law of Segregation Mendel’s Monohybrid Crosses: An Example 9 10 Mendelian Inherita Law of Segregation Each individual has a pair of factors (alleles) Each for each trait for The factors (alleles) segregate (separate) The during gamete (sperm & egg) formation during Each gamete contains only one factor (allele) Each from each pair from Fertilization gives the offspring two factors Fertilization for each trait for 11 Mendelian Inherita Modern Genetics View Each trait in a pea plant is controlled by two Each alleles (alternate forms of a gene) alleles Dominant allele (capital letter) masks the Dominant expression of the recessive allele (lowerexpression case) Alleles occur on a homologous pair of Alleles chromosomes at a particular gene locus chromosomes Homozygous = identical alleles Heterozygous = different alleles Homologous Chromosomes 12 13 Mendelian Inherita Genotype Versus Phenotype Genotype Genotype Refers to the two alleles an individual has for Refers a specific trait specific If identical, genotype is homozygous If different, genotype is heterozygous Phenotype Phenotype Refers to the physical appearance of the Refers individual individual 14 Mendelian Inherita Punnett Square Table listing all possible genotypes resulting Table from a cross from All possible sperm genotypes are lined up on All one side one All possible egg genotypes are lined up on the All other side other Every possible zygote genotypes are placed Every within the squares within Punnett Square Showing Earlobe Inheritance Patterns 15 16 Mendelian Inherita Monohybrid Testcross Individuals with recessive phenotype always Individuals have the homozygous recessive genotype have However, Individuals with dominant However, phenotype have indeterminate genotype phenotype May be homozygous dominant, or Heterozygous Test cross determines genotype of individual Test having dominant phenotype having One-Trait Test Cross Unknown is Heterozygous 17 One-Trait Test Cross Unknown is Homozygous Dominant 18 19 Mendelian Inherita Two-Trait Inheritance Dihybrid cross uses true-breeding plants Dihybrid differing in two traits differing Observed phenotypes among F2 plants Formulated Law of Independent Assortment ­ The pair of factors for one trait segregate The independently of the factors for other traits independently ­ All possible combinations of factors can occur All in the gametes in Two-Trait (Dihybrid) Cross 20 Two-Trait Test Cross 21 22 Mendelian Inherita Human Genetic Disorders Autosome - Any chromosome other than a sex Autosome chromosome chromosome Genetic disorders caused by genes on autosomes Genetic are called autosomal disorders Some genetic disorders are autosomal dominant ­ An individual with AA has the disorder ­ An individual with Aa has the disorder ­ An individual with aa does NOT have disorder Other genetic disorders are autosomal recessive ­ An individual with AA does NOT have disorder ­ An individual with Aa does NOT have disorder, but is a An carrier carrier ­ An individual with aa DOES have the disorder Autosomal Recessive Pedigree Chart 23 Autosomal Dominant Pedigree Chart 24 25 Mendelian Inherita Autosomal Recessive Disorders Tay-Sachs Disease Progressive deterioration of psychomotor Progressive functions functions Cystic Fibrosis Mucus in bronchial tubes and pancreatic Mucus ducts is particularly thick and viscous ducts Phenylketonuria (PKU) Lack enzyme for normal metabolism of Lack phenylalanine phenylalanine Cystic Fibrosis Therapy 26 27 Mendelian Inherita Autosomal Dominant Disorders Neurofibromatosis Tan or dark spots develop on skin and darken Tan Small, benign tumors may arise from fibrous Small, nerve coverings nerve Huntington Disease Neurological disorder Progressive degeneration of brain cells ­ Severe muscle spasms ­ Personality disorders A Victim of Huntington Disease 28 Huntington Disease: Normal and Diseased Brain 29 30 Mendelian Inherita Incomplete Dominance Heterozygote has phenotype intermediate Heterozygote between that of either homozygote between Homozygous red has red phenotype Homozygous white has white phenotype Heterozygote has pink (intermediate) Heterozygote phenotype phenotype Phenotype reveals genotype without test Phenotype cross cross Incomplete Dominance 31 32 Mendelian Inherita Multiple Allelic Traits Some traits controlled by multiple alleles The gene exists in several allelic forms (but each individual The only has two) only ABO blood types The alleles: IA = A antigen on red cells, anti-B antibody in plasma IB = B antigen on red cells, anti-AB antibody in plasma I = Neither A nor B antigens, both antibodies Phenotype (Blood Type) A (actually AA or AO) B (actually BB or BO) AB O (actually OO) Genotype IAIA or IAi IBIB or IBi IA IB ii Inheritance of Blood Type 33 34 Mendelian Inherita Polygenic Inheritance Occurs when a trait is governed by two or Occurs more genes having different alleles more Each dominant allele has a quantitative effect Each on the phenotype on These effects are additive Result in continuous variation of phenotypes Height in Human Beings 35 Frequency Distributions in Polygenic Inheritance 36 37 Mendelian Inherita Terminology Pleiotropy A gene that affects more than one gene characteristic of an individual characteristic Sickle-cell (incomplete dominance) Codominance More than one allele is fully expressed ABO blood type (multiple allelic traits) Epistasis A gene at one locus interferes with the gene expression of a gene at a different locus expression Human skin color (polygenic inheritance) Environment and Phenotype: Himalayan Rabbits 38 39 Mendelian Inherita Review Blending Inheritance Monohybrid Cross Law of Segregation Modern Genetics Genotype vs. Phenotype Punnett Square Dihybrid Cross Law of Independent Assortment Human Genetic Disorders Ending Slide Chapter 11 Mendelian Inherita ...
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This note was uploaded on 01/22/2012 for the course BIOLOGY SC Bio Sci 93 taught by Professor Dr.dianeo'dowdanddr.rahulwarrior during the Summer '10 term at UC Irvine.

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