BSC 1005 Spring 2013 Exam 1 Study Guide Lecture 1 1 Genetics study of the basis of biological variability and how biological characteristics are inherited a Located in DNA proteins a Influenced by 2 Genes code for individual units of information which is read out in our body by 3 Gregor Mendel The father of genetics born in a peasant family Became Monk in Austria i Franz Unger Botanist did not believe in fixity of species ii Christian Doppler Physicist emphasized measurement and experimentation b Mendel s Particulate Theory of Inheritance Inheritance is due to the passage of discrete particulate factors from one generation to the next in an unchanged form 1 Mendel tested this idea with Pea plants a Advantages of Pea Plants For Genetics i Peas can be cross pollinated or self pollinated ii Pure bred varieties were available iii Peas make lots of offspring 4 Ancient Ideas about Inheritance Both of these ideas were wrong and is what made Mendel rethink of ideas a Blending Theory of Inheritance The characteristics of the parents are blended in the offspring b Doctrine of the Fixity of Species Each species has a fixed and unchanging set of biological characteristics 5 Problems with the Blending and Fixitity of Species Ideas a Children are not always intermediate between their parents b Inbreeding and crossbreeding have been used for thousands of years to make new varieties of animals and plants i Cross breeding produces new varieties of animals and 6 Mendel worked with Pure Breeding varieties of Peas each had two different plants forms of the same trait a Pure breeding Red vs Pure breeding White b Pure breeding or true breeding always produce progeny of the same type when crossed with themselves or another individual of the same variety i Red flowers x Red flowers Red flowers ii White flowers x White flowers White flowers c Trait Flower color or Plant Height Tall vs Dwarf i Mendel worked with 7 different traits Pod Shape Pod Color Flower Position Seed Shape Seed Color Flower Color and Plant Height 7 Mendel s Law of Inheritance Law of Random Segregation a Each trait is controlled by a pair of factors genes i Genes a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring 1 Height Color ii Alleles alternate forms of the same gene 1 Tall vs Dwarf Red vs White b One factor is dominant and the other is recessive i Tall is dominant over Dwarf Red over White c During sexual reproduction each parent passes one allele from each gene pair to the offspring Chance determines which allele is passed in sexual reproduction the paired factors separate during gamete formation Pairs reform in fertilization d Here s the Random Segregation For each gene pair we inherit one allele from each parent Lecture 2 1 2 Some Important Genetic Terms Inheritance is due to the passage of discrete particulate factors from one generation to the next in an unchanged form a Homozygous both alleles of a gene pair are the same b Heterozygous two different alleles c Genotype genetic makeup d Phenotype appearance Question If a pure bred tall pea plant is crossed with a pure bred dwarf plant what fraction of the progeny will be dwarf a 100 b 75 a 25 b zero Tall is Dominant Over Dwarf 3 How do we identify dominant and recessive genes in humans Pedigree 4 Genetic Disorders to Know a Cystic Fibrosis Recessive and lethal i Defect in salt movement in and out of cells ii Most common genetic defect in Caucasians 1 2000 b Phenylketonuria Recessive i Defect in amino acid metabolism ii Mental retardation unless a special diet is used c Polydactyly Dominant d Achondroplastic Dwarfism Dominant i Defect in collagen e Marfan s Syndrome Dominant i Defect in collagen f Porphyria autosomal dominant i Inability to metabolize porphyrin wine colored urine seizures dementia psychosis g Muscular Dystrophy Recessive But occurs almost exclusively in males i Progressive loss of muscle function Lecture 3 1 Probability in Inheritance Examples Questions a 100 b 50 c 25 d zero a Product Rule multiply the probability that two or more independent events will BOTH or all occur b Addition Rule when an outcome can be reached in more than one way than you add the probabilities of the independent ways of reaching it 1 If a tall plant that is heterozygous is crossed with a dwarf plant what fraction of the progeny will be tall 2 The probability that any given child will be a boy or a girl is 1 2 or 50 The probability that any given child will be a boy or a girl is 1 2 or 50 a Answer 3 What is the chance your first two children will both be boys a 1 2 x 1 2 1 4 or 25 4 What is the chance your first two children will both be girls a 1 2 x 1 2 1 4 or 25 Child 1 1 2 boy 1 2 boy 1 2 girl 1 2 girl Child 2 1 2 boy 1 2 girl 1 2 boy 1 2 girl 5 If you have three children what is the chance that they will all be girls a 1 2 x 1 2 x 1 2 1 8 12 5 6 If you have two children what is the chance you will have at least one girl a Chance of having at least one girl is 75 7 If both you and your wife are carriers for CF what is the chance that your first child will get the disease a 100 b 75 c 50 d 25 e zero a Smooth b Wrinkled 8 Peas may be smooth or wrinkled and both types can be true breeding A pure bred pea plant with smooth seeds is crossed with a pure bred plant with wrinkled seeds and all the offspring have smooth seeds Which allele is dominant 9 If two pea plants with smooth seeds are crossed and 75 of the progeny have smooth seeds and 25 have wrinkled seeds what are the genotypes of the parents a S S and s s b S S and S s c S s and S s 10 Is the trait shown in this pedigree dominant or recessive Lecture 4 A Dominant B Recessive 1 Mendel published in 1865 biologists did not Believe his data 1 Biologists in the 1800 s did not know of any structures in cells that behaved like Mendel s factors i 1880 s Fertilization Sperm Egg Chromosomes discovered ii 1900 Mendel s work is rediscovered iii 1903 Walter Sutton chromosomes behave like Mendel s factors 2 The Chromosomes carry the Genes 3 All living things are made of cells 4 Cells are structurally complex 5 Chromosomes appear in nucleus at start of cell division i Before division each chromosome has two arms Chromatids ii Sister chromatids are exact duplicates 1 They carry the same genes and alleles 6 Each cell has two copies of each chromosome 4 chromosomes 2 pairs 2 pairs of homologous chromosomes …
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