DESIGNER GENES KEY SSSS By Andromeda215 This test will take 50 minutes in total and is conducted in stations. Pay attention to the top of the page, as it will tell you how many minutes are permitted for that specific station. Show all your work/ calculations. You are permitted Two non-graphing calculators and One 8.5” by 11” cheat sheet. Best of luck! Team name: __________________________ Team number: C - ____ Participant names: ____________________________ _________________________________ STATION 1: GENETIC CROSSES 5 MIN You are a geneticist studying a eukaryotic, sexually reproducing, microbial species known colloquially as Goofy Goobers. We will be calling them Goobers for short. Goober colonies have been found to be either red, purple, blue, or white. For 1-2, options are separated by slashes. Circle the most appropriate option. 1. Red is an example of a Character/Trait. 2. Colony color is an example of a Character/Trait. 3. Describe the molecular basis for dominance. In other words, what makes certain alleles appear to “cover up” the effects of another allele? Dominant alleles tend to code for proteins (Ex: presence of Rh protein, presence of more melanin in hair) Recessive tends to code for the absence of those proteins. (Ex: Blood type Rh- is just an absence of the Rh protein, alleles corresponding to light blonde hair codes for no/less melanin) Therefore, if a person is heterozygous for a gene, they will still produce the protein encoded by the dominant allele, so they will display the corresponding phenotype. 4. Define the term “True-Breeding”. Has been verified homozygous. 5. Define the term “Mendelian Trait”. Character that is controlled by 1 locus, and there are only 2 possible alleles (completely dominant & completely recessive) 6. State Mendel’s Law of Independent Assortment and explain why/how it is not always followed in biology. “The allele that a gamete receives for 1 gene does not influence alleles received for different genes”. Not always followed because of genetic linkage. It is statistically less likely for genes on the same chromosome to segregate than genes from different chromosomes. 7. Explain the difference between genotype and phenotype and state the relationship between these two terms. Genotype is a representation of alleles that an organism possesses (can be overall, or in reference to a single gene. Ex: Gg and GG are different genotypes, but they can produce the same phenotype. Phenotype describes how the alleles are expressed. An organism may express a dominant allele, but that doesn’t really tell you much about what that organism’s genotype may be (heterozygous or homozygous dominant) Genotype determines phenotype. 8. Explain the difference between cis and trans heterozygotes. Cis heterozygotes: AB/ab Trans heterozygotes: Ab/aB 9. Explain the difference between incomplete dominance and codominance on the protein level. Inc dominance: Because one recessive & one dominant allele is present, only some protein is made, which affects the phenotype. Phenotype will turn out to look like a mix between recessive and dominant. (if it were both dominant, more protein would be made, so wouldn’t get this phenomenon) Codominance: Two different dominant alleles are present. Each of those alleles creates a different protein, so both corresponding phenotypes are expressed. STATION 2: GENETIC DISEASE 5 MIN Now you are a genetic counselor who moonlights as a lab technician. 10. Define an ideogram: A diagram of a karyotype, where chromosomes are grouped together based on centromere position and ordered in decreasing size. 11. Describe the features that make a karyotype asymmetrical: Unusual centromere position, very large size difference between smallest and largest chromosomes 12. The human Y chromosome is closest in size to Chromosome #7. 13. Humans have 44 nuclear, autosomal chromosomes. 14. Chromosome 1 is: a. The physically largest chromosome. b. The chromosome with the largest region of protein-coding DNA. c. The physically smallest chromosome. d. The chromosome with the largest region of ncDNA. e. None of the above 15. Define “metacentric”: Centromere is approximately in the middle of the chromosome, making it look symmetrical. 16. Name the location where DNA is found in the mitochondria. matrix 17. Give an explanation as to why it is (generally) physically impossible for fathers to pass on mitochondrial DNA to their children. (Hint: in order to get full points, there is a specific gene that you must talk about) After sperm fertilizes egg, the mitochondria inside the sperm kill themselves, controlled by cps-6 gene. 18. Name the primary physiological process that human mtDNA makes possible. (Hint: specifically, mtDNA codes for 13 enzymatic subunits in order to carry out this process) Oxidative phosphorylation 19. In pedigrees, Roman numerals are used to denote generations. Arabic numerals are used to denote individuals in each generation. 20. Define “Euploidy”: Correct, complete set of chromosomes 21. Define “nondisjunction”. A mistake in chromosomal separation during cell division that results in daughter cells having an incorrect number of chromosomes. 22. If you track meiotic division from oogonium to the mature egg, there will be 3 polar body/bodies left at the end, which are a result of uneven cytoplasmic division. Two of the final four haploid cells have n + 1 chromosomes, and the other two have n – 1 chromosomes. State whether nondisjunction occurred. If it did, also state which state of meiosis it occurred in (be as specific as possible). Nondisjunction occurred during Anaphase I. STATION 3: GENETIC DISEASE (cont.) 15 MIN Recap: Now you are a genetic counselor who moonlights as a lab technician. You are consulting with a family who has been afflicted with Poppy syndrome. 23. There are two living grandparents, named Nadejda and Patrick. They are married to each other. Nadejda is affected, her husband is not. They have 3 children, and they were all affected. Their names are Rohan, Sandy, Fillmore. Rohan is the oldest, and Sandy is the middle child. Rohan has a wife who is not affected, and their three children were born in this order: daughter, son, daughter. None were affected. Sandy has an unaffected husband. Their three children were born in this order: daughter, son, son. All were affected. Fillmore has a wife who is not affected, and their three children were born in this order: son, daughter, son. None were affected. Draw the pedigree, and label generations/individuals properly. 24. Predict this disease’s mode of inheritance: mitochondrial 25. Not all affected display the same symptoms. For example, Sandy only needs to take a few medications daily to keep her symptoms under control, but her daughter is a permanent patient at the hospital. State the name of this phenomenon. Taking into account the mode of inheritance, explain why this happens: Variable expressivity. Just because a person is affected with the disease doesn’t mean that all/most mitochondria in their cells contain the mutation-causing allele. Those that are less affected probably have a lower percentage of faulty mitochondria in their cells, and those more affected have a higher percentage. Sandy’s daughter may have been more affected because during meiosis, the egg that she came from happened to get a relatively higher concentration of mitochondria as a result of random cytoplasmic splittage. You have carried out some genetic tests for some newborns. Baby #1: Baby #2: Baby #3: Baby #4: For 34-37, state the baby’s sex and the colloquial name of any identifiable disorders (if none found, write “Healthy”.) In either case, also state the cytogenetic notation. 26. Baby #1: Female, Cri-du-Chat syndrome. 46, XX, del(5p) 27. Baby #2: Male, healthy. 46, XY 28. Baby #3: Male, Klinefelter’s syndrome. 47, XYY 29. Baby #4: Female, Patau syndrome. 47, XX, +13 Now you are meeting with a boy and his family. The boy possesses severe intellectual disability and they want to figure out whether it is genetic. You conduct a basic karyotype, compile a pedigree, and test for trinucleotide repeats. 30. Describe the steps needed to conduct a standard karyotyping, starting with cell extraction and ending with visualization. 1. Blood draw/ bone marrow biopsy/ amniocentesis 2. Insert in phytohemagglutinin solution 3. Use colcemid 4. Insert in hypotonic KCl soln 5. Treat with alcohol & acetic acid 6. Put on glass slide 7. Stain with Giemsa dye 31. You interview the family. His mother is slightly affected, and his maternal grandfather is obviously affected. His father, maternal grandmother, and paternal grandparents are not affected. Construct the pedigree. 32. Using the pedigree and karyotype, predict whether this disorder is heritable. If so, state the mode of inheritance. Yes, X-linked dominant. 33. You test for trinucleotide repeats, and there are around 400 CGG repeats in the X chromosome. State whether this is significant. If so, state the disorder that you would diagnose him with. Significant. Fragile X syndrome. STATION 4: GENE STRUCTURE + GENE TRANSFER 10 MIN You are a geneticist who is trying to insert a bioluminescence operon into E. Coli. 34. Name an example of an operon that codes for bioluminescence: lux operon. For 35-58, write down the definition of the word. 35. Cistron DNA/RNA section coding for a single polypeptide. 36. Open Reading Frame Protein-coding DNA section. 37. Constitutional Expression Gene is constantly expressed at some level in order for normal cell machinery to function. 38. Downstream In same direction RNA polymerase would go, transcribing from promoter to terminator sequence. 39. Operon Set of adjacent genes coding for proteins with a similar purpose, controlled by a single promoter & operator. 40. TATA box Eukaryotic TATA-binding protein bind site (binding induces formation of the PIC) 41. Pribnow box Prokaryotic. Initial site of double helix splittage after RNA polymerase binding.