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Designer Genes – EXAM KEY2019 UMD InvitationalTotal Points Possible (written test): 100Explain the central dogma and give an example that is the exception to the central dogma. (5 points)Mentions DNA RNA Proteins via transcription and translation (3 points). 2 points if no mention of transcription/translation. Mentions retroviruses that convert RNA DNA (2 points)Match the following terms to the appropriate response. Not all answers will be used. (12 points) __D__ Recognizes specific base paired sequences in double stranded DNA and can cleave/cut the DNA at those sequences __B__ Extrachromosomal DNA that can replicate independently and can be used to carry recombinant DNA __G__ Synthesizes DNA from an RNA template__A__ Synthesizes RNA from a DNA template __I__ Degrades RNA from an RNA-DNA hybrid __H__ Joins DNA strands by catalyzing formation of a phosphodiester bondRNA polymeraseb. Cloning vectorDNA polymerased. Restriction enzymes Polynucleotide kinasef. Topoisomerase Reverse transcriptaseh. DNA ligase RNase HIndicate if the following process is associated with Meiosis I, II, both, or neither. (12 points each)______neither__________ DNA replication_____ meiosis I_________ Basis of independent assortment______meiosis II__________ Chromosomal segregation defect resulting in the same alleles of a parental gene locus being pass to the gamete______meiosis II__________ Separation of sister chromatids_____meiosis I ___________ Crossover events resulting in recombination ________both________ Spindle attachment checkpointList the following enzymes in the correct order based on the role they play in lagging strand synthesis. Explain the function of each enzyme. (1 point for correct order, 1 point for correct function)DNA polymerase IIILigase Primase DNA polymerase I Primase: adds RNA primer that DNA polymerase can use as a 3’ end for replicationDNA Polymerase III: synthesizes the reading and lagging strand DNA Polymerase I: removes RNA primer and synthesizes gapsLigase: joins Okazaki fragments together Fill in the blank for the following (18 points)An observable trait is called a phenotype, whereas the genetic information underlying a trait is called a genotype. (4 points)Ribosomal profiling is a method to identify which RNA transcripts are being actively translated. (2 points) Trans complementation is when one gene is brought into a bacterium on a plasmid via conjugation to test for rescue of a mutation. (2 points) Yeast-2-hybrid is a technique to identify protein-protein interactions. (2 points)In a pedigree, the proband is the first individual to present with the genetic disorder. (2 points)Non-disjunction is when the chromosomes fail to separate during cell division. (2 points)Kinetochore is a protein complex at the centromere that spindle fibers attach to during mitosis. (2 points)If two or more independent events produce the same result, the probability that either will occur is the sum of their probabilities. (2 points)Multiple Choice (10 points)Which phrase describes the process that led to the development of different beaks in Darwin’s finches? (2 points)Gene transferAdaptive radiationNeutral selectionConvergent evolutionAs the temperature is increased, which of the following DNA sequences would denature first. (2 points)TTTGCTGTAATAGTCGATCGTTCCGTCGTAACGGACTGCATGCTHow do bacteria avoid destroying their own DNA with their restriction endonucleases? (2 points)Bacterial restriction endonucleases only affect virus and eukaryotic DNA and do not affect bacterial DNA. Bacteria methylate restriction endonuclease recognition sites in their own genome. Bacteria do not have the recognition sequences for their own restriction endonucleases in their genome.Restriction endonucleases cannot penetrate the bacterial nuclear membrane.Which of the following are true about histones? Select all that apply. (2 points)Histones have a negative chargeHistones form a tetramer A nucleosome consists of DNA plus a core histone particle Histones are highly conservedA cross between tall plants (Tt) and short plants (tt) produced six offspring. What is the probability that all six offspring are tall? (2 points)1/21/12 1/161/64Short Answer In an experiment, you have a tall plant that produces round peas. Tall and round are dominant and the plant is heterozygous for both traits. The plant is the self-fertilized. hat is the probability that a single offspring is tall and has wrinkled peas? Answer in fractions is OK. (5 points)Probability of tall= ? Probability of wrinkled= ?Probability of tall and wrinkled= (3/4)(1/4)= 3/16A tall plant with purple flowers with genotype TtPp was self-fertilized. There were 8 offspring. What is the chance that at least one of the plants was short? No need to simplify. (5 points)Probability of tall= ? Probability all are tall= (3/4)^8 Probability at least one is short= 1 – (3/4)^8 Explain why lagging strand synthesis differs from leading strand synthesis. (5 points)DNA runs anti parallel so one strand runs 5’ 3’ while the other runs 3’ 5’. DNA polymerase can only synthesize in 5’ 3’ so the leading strand is synthesized continuously toward the replication fork while the lagging strand is synthesized discontinuously away from the fork. Mentions antiparallel strands (1 point), mentions continuous synthesis of leading strand (2 points), mentions discontinuous synthesis of lagging strand (2 points)What is the difference between co-dominance and incomplete dominance? Give an example of either one. (5 points)Co-dominance is when both traits are equally expressed in the heterozygote, while incomplete dominance is when the heterozygote is a mix of both traits. Mentions equal expression for co dominance (2 points), mentions mixed expression for incomplete (2 points), valid example (1 point) One of the traits studied by Mendel was pea color. Plants carrying the recessive gene resulting in green peas senesce (do not yellow with age) like wildtype peas. Design a genetic screen to identify more genes important in pea senescence. Hint: pick a starting pea strain (wildtype or green), next mutagenize and generate homozygous recessive lines to screen. What phenotype are you looking for and why? (10 points) Use green peas and mutate certain genes and look for if the peas yellow with age. If they do it indicates the mutated gene was important for maintaining pea color. Tiebreaker Questions (15 points)Indicate how nucleotides are modified and what the purpose was for the modification for Sanger sequencing. (5 points) Dideoxy nucleotides are used that stop synthesis when added to the complementary sequence. Used to determine the last nucleotide of the fragment which could be run in a gel to determine the sequence of DNA24.Briefly explain how CRISPR-Cas technology works (5 points)CRISPR-Cas9 is a unique technology that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence25.What does RFLP stand for and how is it used in DNA analysis? (5 points)In Restriction fragment length polymorphism analysis, the DNA sample is broken into pieces (digested) by restriction enzymes and the resulting restriction fragments are separated according to their lengths by gel electrophoresis. Can be used in DNA fingerprinting. ................
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