Biosc 0150 Foundations of Biology I Review 6 chapter 13 Review chapter 13 Mendel and the Gene 1 What is the difference between an organism s genotype and phenotype The genotype of an organism is the composition of alleles in its genetic material The phenotype is the physical expression of alleles based on the proteins encoded by the genotype 2 Review crosses fill in the table Monohybrid Cross Reciprocal Cross Dihybrid Cross Test cross A cross between two parents that carry two different genetic determinants for the same trait In more modern terms a cross between two parents that are both heterozygous for one trait A set of matings where you switch the maternal and paternal phenotypes from the previous mating and perform the cross A cross between two individuals who are both heterozygous for two trait A cross between an individual of unknown genotype with an individual who is homozygous recessive for that trait Useful for determining the genotype for the unknown individual 3 Vocabulary review Dominant allele Recessive allele Homozygous Heterozygous Hybrid in heterozygotes and Allele that produces the dominant phenotype homozygotes Allele that produces the recessive phenotypes only in homozygous recessive individuals Containing two of the same alleles for a trait Containing two different alleles for a trait Offspring from a cross between two parents homozygous with different genotypes 4 Introduction to Genetics a What were the two inheritance Blending leading hypotheses for the pattern of Inheritance traits observed are a blending of mother and father s traits Inheritance of acquired characters traits observed are modified traits from parents b What is a model organism Why was the garden pea such a good one A species that is used for research because it is practical and because conclusions drawn from studying it turn out to apply to many other species as well The garden pea was a good model because Mendel could control which parents were involved in mating and it had very easy categorical traits color shape c The observable trait of an individual is known as its Phenotype d What is a pure line Consists of individuals that produce offspring identical to themselves when they are self pollinated or crosses to another member of the pure line population e What are Mendel s 5 claims rules i Peas have two alleles ii Alleles do not blend together iii Each gamete contains one allele iv Male and female contribute equally to genotype of offspring v Alleles can be dominant or recessive Adel Anthony Kathleen Megan Dr Swigonova Page 1 of 9 Biosc 0150 Foundations of Biology I 5 Single Trait Inheritance Review 6 chapter 13 a The adults used in an initial experimental cross are the Their progeny offspring are the Parental generation F1 generation b True or False Individuals with the dominant phenotype have a higher fitness than do individuals with the recessive phenotype FALSE The term dominant and recessive identify only which phenotype is observed in individuals carrying two different alleles Example Huntington s disease is dominant but fatal c What is the point of doing a reciprocal cross A reciprocal cross can determine whether or not a trait is sex linked d Different versions of the same gene are known as which make up an individual s Alleles genotype e What is the principle of segregation Each gamete contains one allele of each gene alleles must separate into different gametes during meiosis f If the allele R is dominant to r what are the following genotypes vi RR Homozygous dominant vii Rr Heterozygous viii rr Homozygous recessive In humans pigmented eye color brown is dominant to un pigmented eye color blue B brown b blue In a test cross the mother had blues eyes and the father had brown eyes a Fill in the 2 possible Punnett Squares one where the father is homozygous dominant for brown eyes and the other where he is heterozygous Bb Bb Bb Bb Bb bb Bb bb 6 b If the father was homozygous dominant for brown eyes ix What is the probability of having a child with brown eyes 1 x What is the probability of having a child with blue eyes 0 c If the father was heterozygous for brown eyes xi What is the probability of having a child with brown eyes 1 2 xii What is the probability of having a child with blue eyes 1 2 d If both parents had blue eyes xiii What is the probability of having a child with brown eyes 0 xiv What is the probably of having a child with blue eyes 1 e If both parents were heterozygous for brown eyes xv What is the probability of having a child with brown eyes 3 4 xvi What is the probably of having a child with blue eyes 1 4 f If the mother has brown eyes and a child has blue eyes xvii What is the genotype of the mother Bb xviii What are the possible genotypes of the father Bb bb xix What genotype can the father NOT be BB Adel Anthony Kathleen Megan Dr Swigonova Page 2 of 9 Biosc 0150 Foundations of Biology I 7 Experiments with 2 Traits The Dihybrid Cross and Testcross a What is the definition of a Dihybrid cross Review 6 chapter 13 A mating between two individuals who are heterozygous for two traits example on page 237 b What were the two possibilities assortment type for the Dihybrid cross that Mendel hypothesized Which one did he find actually occurred experimentally In this experiment what generations did he need to mate to show the difference between the two Independent and dependent assortment independent two F1 generation members c What were the phenotypic ratio results of the cross described above for the second question page 237 9 3 3 1 d What is the definition of a test cross Why is this useful for experimenters A testcross is a cross between two parents one that contributes only recessive alleles to determine the unknown genotype of the second parent It is useful because the genetic contribution of the homozygous recessive parent is known and it allows the experimenters to test the genetic contribution of the other parent which is unknown They can then use this parent for another cross now that they know its genotype e If a testcross is performed for a phenotype for dominant round and dominant yellow seed traits what are the possible genotypes of this parent If the results show a 1 1 1 1 with four different phenotypes what is the phenotype of the unknown parent What if all of the offspring had the same phenotype would the parent genotype be the same RrYy and RRYY RrYy no it would be RRYY 8 Chromosome Theory of Inheritance What does this theory state briefly Mendel s