Transcript Genetics
Genetics Genetics Bell: What is Genetics? Study of heredity passing of traits from parents to offspring Traits- Visible characteristics Gregor Mendel Watch video clips- DVD and “From the Gardent to the Genome” YouTUBE- click for link “Father of Genetics” Austrian Monk Conducted experiments with peas Used numbers in the study of biology Gregor Mendel Experimented with Self-pollination - fertilization within itself Creation of pure-breed or true-breed offspring identical to parents Cross-pollination - fertilization of one by another Offspring from both parents Gregor Mendel How many experiments were needed to determine conclusive results? Heads/Tails Activity Round x Wrinkled = 7324 offspring Yellow x Green = 8023 offspring Axial x Terminal = 858 offspring Purple x White = 929 offspring Inflated x Constricted = 1181 offspring Green x Yellow = 580 offspring Tall x Dwarf = 1064 offspring Mendel’s First Experiment- Terminology and Crosses Parental Generation - P - Purebreds for each parent 1st Filial - F1 (first generation) offspring of cross (children) created hybrid - cross between 2 parents 2nd Filial - F2 (second generation) Grandchildren Mendel’s Conclusions I. Traits are determined by a “factor” Now termed GENES Different forms of a gene are called ALLELE II. Each “factor” is inherited separately III. Each trait is determined by one of the “factors” inherited from the parents Principle of Dominance Dominant masks the expression of the recessive Bellringer - Genetics Day 2 What will be the fur color of the offspring of Benjamin Bear and Elizabeth Bear? Genetics Terminology Purebred or True-breed Dominant Recessive Genotype Phenotype Homozygous Heterozygous Practice with REEBOPS How many show the dominant phenotype for body segments? 4 How many show the recessive eye number? 1 What is the genotype of those showing the recessive eye number? ee What is the genotype of those showing the dominant phenotype for eye number ? EE or Ee Are there any traits that are not dominant or recessive? *Which of the traits shown are heterozygous? Orange Nose, 2 antennae, Hump #, Nose Color, Antennae # Teddy Bear Genetics Law of Segregation = 2 forms of a gene/ allele are separated during meiosis (one to each gamete) Complete the Teddy Bear Genetics Probability Likelihood that an event will happen Ex) coin toss 1 coin flip = 1/2 chance or 50% Heads 3 times in a row = 1/2 x 1/2 x 1/2 = 1/8 1/2 chance for each event (flip) Principles of Probablility can be used to predict genetic outcomes Genetics and Probability Ability to roll tongue = dominant trait Can you determine your genotype? With a partner: John is heterozygous for tongue rolling and Nancy cannot roll her tongue. What is the chance that they will have children that cannot roll their tongue? How did you figure it out? Genetics and Probability Punnett Square - tool used to predict genetic combinations Tongue Rolling problem with punnett square Closure problem: George and wife are both heterozygous for widow’s peak. What percentage of their children will have a Widow’s peak? HW: Bikini Bottom Genetics Genetics and Probability Day 3 Bellringer: Mom and Dad both have free earlobes. Junior also has free earlobes. His sister has attached earlobes. What are Mom and Dad’s genotypes in relation to earlobes? What is the chance that they will have another child with attached earlobes? Check Bikini Bottom Genetics Classwork: Genetics Worksheet Genetic Crosses Test Cross: used to determine genotype of dominant phenotype Cross an “unknown” dominant with a recessive Why? Genetic Crosses - 2 traits Principle of Independent Assortment genes segregate independently during meiosis cause of different genetic combinations in gametes Dihybrid cross both parents are hybrid for 2 traits Genetic Crosses - 2 traits Dihybrid worksheet practice Mendel’s peas activity Dihybrid Crosses Beyond Dominant and Recessive Incomplete Dominance - neither allele is dominant over the other Purebreds phenotypes are 2 extremes Hybrid phenotype is in the middle Incomplete Dominance 4 o’clock Flowers X Beyond Dominant and Recessive Codominance Both alleles are dominant Hybrid shows both traits CodominanceRoan Cattle Bell: Day 5 How are codominant and incomplete dominant alleles different than dominant and recessive alleles? AGENDA Incomplete Dominance Practice Multiple Alleles Blood Typing Lab Blood Type Problems Multiple Alleles Humans have ______ blood types Alleles: Type A= B= AB = O= Human Heredity: Day 6 Bell: What is the genotype of the possible children if a heterozygote for Widow’s peak marries a homozygous recessive (straight hairline)? What is/are the possible phenotype(s)? AGENDA 1. Independent Projects 2. Blood Typing 3. Pedigrees 4. Sex-linked traits *Quiz NEXT time* Human Heredity Human Chromosomes Human cell = 46 chromosomes (23 pairs) 1 set from Mom (egg) : 1 set from Dad (sperm) 2 of those are known as sex chromosome Female = XX Male = XY Remaining 44 chromosomes = autosome Pedigree Chart that shows the relationships within a family Often used to determine the mode of inheritance Pedigree (cont.) Female = Affected Female = Male = Affected Male = If a heterozygote is known then half of the shape is shaded Pedigree Practice Worksheet Pedigree Practice: Autosomal Dominant? A. B. C. Draw each pedigree Assume that the affected trait is dominant. Write the genotypes beside each recessive individual Is it possible for this trait to be autosomal dominant? -Circle if possible or X if not possible Can two affected individuals have unaffected children? Pedigree Practice Autosomal Recessive? A. B. C. Assume the trait is recessive. Draw the pedigree and write the genotype beside each person. Is it possible for the trait to be recessive? - Circle if possible or X if not possible If the trait is autosomal recessive, what can you conclude the children will be of two affected parents? Pedigree Practice Carrier Heterozygote that “carries” the affected allele, but does not express the allele (Allele remains hidden.) ** Who are the carriers? Is the affected trait autosomal dominant or recessive? Why? Day 7 Bell: Fifty wavy-haired couples decide to form a cool. commune, because they think wavy hair is Each couple has twoofchildren. Out of the“uncool” 100 children, how many them should have straight hair? (Of course, they willcurly-haired have to be excommunicated, along with their siblings, once they reach adulthood.) AGENDA Quiz Pedigree Sex-linked Traits Sex-Linked Genes Pattern of inheritance is located on the Xchromosome or the Y- chromosome Y is much smaller Therefore, there are more X-linked disorders/traits What numbers to you See? Ex. Colorblindness X-linked disorder Most common in ? Males (1/10) Females (1/100) Allele Definition - Colorblind Problem Marian’s father is colorblind. Marian herself has normal color vision. Marian and her husband, Martin, who is also colorblind, have just had their first child; a son they have named Mickey. (Write the genotypes of Marian and Martin.) a. What is the probability that their son is colorblind? b. If Martin were not colorblind, how would this affect the prediction about Mickey? c. If Marian and Martin were to have a girl, who they would name Minnie, what is the probability that she would be colorblind? X-linked BELL Hemophelia is a hereditary disease in which the blood does not clot. The allele for normal blood clotting is carried on the X chromosome. 1. A carrier female marries a hemophilic man. How many male children will have hemophilia? How many female children? 2. A normal woman whose father had hemophilia marries a normal man. What is the chance that their children will have hemophilia? 3. Todd is not colorblind. He is married to Ann whose father was red-green colorblind. Todd and Ann have 2 children, Ed is colorblind and lisa is not. What are the genotypes of Todd, Ann, Ed, and Lisa? Pedigree Practice A B C Draw the pedigree and write the genotypes beside each individual. Assume X-linked recessive. Is it possible for it to be x-linked recessive? What can you conclude about children whose mother is affected by an x-linked recessive trait? X-linked Conclusions What can you conclude about children if only the mother is affected by an X-linked recessive trait? Why is it possible for females to be carriers of Xlinked traits, but not males to be carriers? BELL: PEDIGREE One last time! BELL - Pedigree (one last time). Using the markers, solve the 1, 2, and 3 pedigrees Erase when finished. AGENDA 1. Turn in Alcaptunuria Lab. 2. Karyotype Internet Activity 3. Karyotype notes 4. Genetic Disorders/Disease Project Karyotype Organized profile of a human’s chromosomes Chromosomes are paired by centromere location banding pattern Size Analyzing Karyotypes What can you tell by this karyotype? Analyzing Karyotypes What can you tell by this karyotype? Analyzing Karyotypes What can you tell by analyzing this karyotype? Analyzing Karyotypes What can you tell by analyzing this karyotype? Analyzing Karyotypes What can you tell by this karyotype? Analyzing Karyotypes What can you tell by analyzing this karyotype? Karyotype Analysis: Chromosomal Disorders Nondisjunction- occurs when either homologous chromosome fails to separate during meiosis Results abnormal # of chromosomes in gametes Trisomy = 1 extra homologous chromosome (3) Polysomy = more than 1 extra Monosomy = only 1 chromosome Karyotype Analysis: Chromosomal Disorders High frequency of Nondisjunction in humans Results usually so devastating that it results in miscarriage Only 3 trisomies that result in babies Down’s syndrome - 21 Edward’s syndrome - 13 Patau Syndrome - 18 Nondisjunction: Sex Chromosomes Monosomy (X only) = Turner’s Syndrome Trisomy (XXY or XXXY) = Klinefelter’s Syndrome Trisomy (XXX) - cannot be distinguished from normal females / no affect When would the effect show up? Chromosomal Alterations Deletion Portion of Chromosome lost during cell division (genes lost = usually lethal) Duplication A fragment joins the chromosome and is then repeated Translocation A fragment is moved from one chromosome to another Wrap-Up Bell: What is a karyotype? How is a karyotype created? Human Genetic Disorders Assignment Go to website for assignment Human Disorders/Diseases BELL: What is a karyotype and how is it made? Describe the 3 type of chromosomal alterations. Why do they affect an individual? AGENDA Human Disorders Project (Presentations) Genes and the environment Perfect Baby AGENDA Genetics Quiz #2 Perfect Baby Video Discussion Genes and the Environment Human Genome and Ethics AGENDA Human Genome - gene patenting DNA databases Designer Babies? Video Discussion What are some of the strange and unexpected discoveries made from analyzing the human genome? Why is sequencing the human genome considered such an important and historic event • Video - 7. Who Owns the Genome? What effects might patenting genes have on current research efforts? Do you think genes should be patented? Why or Group Work why not? With your group, read and answer the questions to the case stud “Patenting Genes.” Elect a spokesperson to share your answers. DNA Databases 13. DNA Databases - link What are some ethical issues surrounding the creation of DNA databases? What are some implications of creating DNA chips that would allow doctors to screen newborns for many diseases? Case Study Newborn screening or Genetic Discrimination: read the case study with your group - appoint a spokesperson to share your answers Should we create babies by design? Can we do it now? - link to 15. Genetic Modification Should We Create Babies by Design? - Internet Activity with a partner complete the web based activity through Mr. Lauver’s website (class assignments) What is your position on “Babies by Design”? Why?