BioSc 231 General Genetics Exam 5 Name __________________________________ Multiple Choice. (1 points each) _____ Which of the following is unique to eukaryotic gene expression? A. 5' polyadenylation of mRNA B. Polycistronic mRNA C. Coupled transcription-translation D. Removal of introns E. Polysomes _____ Which of the following statements is true regarding gene expression? A. The 3' end of mRNA corresponds to the carboxyl terminus of the protein B. The first step is the association of mRNA with an intact ribosome C. Involves proof-reading of the mRNA D. Prokaryotic RNA usually undergoes nuclear processing E. Polypeptides are synthesized by addition of amino acids to the amino terminus _____ Which of the following features is common to both DNA replication and transcription? A. Nucleotides are added to the 5' end of the newly synthesized strand B. A sugar-phosphate bond is formed between the 3' hydroxyl and the 5' phosphate C. Deoxyribonucleotides are incorporated into the growing sequence D. Both RNA and DNA polymerase require oligonucleotide priming E. Both RNA and DNA polymerase initiate at promoter sequences _____Transcriptional activators A. Do not require RNA polymerase to initiate transcription B. Do not bind directly to DNA C. Are essential for positively regulated gene transcription D. Are short DNA sequences that increase expression of nearby genes E. Are necessary for constitutive gene expression _____Constitutive gene expression refers to A. Constant, unregulated expression B. Polycistronic mRNA C. Coupled transcription/translation D. Mutant repressor that no longer responds to inducer E. Gene expression following addition of inducer _____ Which of the following statements is true? A. tRNAs are charged by binding to the ribosome B. The anticodon of a tRNA hydrogen bonds to a codon. C. There are more distinct tRNAs than codons D. All bases that can hydrogen bond are possible in the third position E. tRNA has a 5' triphosphate _____ Which of the following is unique to prokaryotic gene expression? A. Coupled transcription-translation B. Exon processing C. 3' polyadenylation D. mRNA capping E. Promoter sequences _____ Which of the following is true regarding gene expression? A. Only one gene can be present within a given DNA sequence B. Mistakes in transcription are corrected by RNA polymerase C. The ribosome binding site lies at the 3' end of mRNA D. A change in genotype always results in a changed phenotype E. A second round of transcription can begin before the preceding transcript is completed _____ Which of the following is true regarding RNA processing? A. Spliceosomes are present in organelles and nuclei B. Involves removal of exons C. Involves removal of one or more introns. D. Occurs in prokaryotes E. None of the above _____ Which of the following occurs only in prokaryotes? A. TATA boxes B. Self-terminating transcription C. Polycistronic mRNA D. Coordinate gene regulation _____A negatively regulated genetic system A. Is more common in eukaryotes B. Requires an effector molecule acting at the promoter C. Is derepressed by an inducer D. Is completely off when repressor protein is present E. All of the above _____ To describe the genetic code as degenerate indicates that A. mRNA is rapidly degraded B. The code is not universal among organisms C. Some amino acids have more than one codon D. Frameshift mutations are tolerated E. Stop codons may have corresponding tRNA molecules _____A positively regulated genetic system A. Is derepressed by inducer B. Is more common in prokaryotes C. Must override an inhibitor D. Is stimulated when protein bound with inducer interacts with the promoter E. All of the above _____Which enzyme cleaves lactose to glucose and galactose? A. Lactase B. Glucose synthetase C. -lactamase D. -galactosidase E. -glucosidase _____The product of the lacI gene A. Is cis-dominant B. Cannot be complemented C. Induces lac operon transcription D. Binds to the operator E. Transports lactose into the cell _____ Normal self-termination of transcription occurs due to the presence of A. stem-loop sequences in mRNA B. Termination proteins C. Multiple RNA polymerase molecules D. Polyribosome formation _____Which of the following statements is true regarding tryptophan biosynthesis? A. It is controlled by attenuation and not repression B. Translation controls transcription C. A high tRNATrp concentration stalls translation at the ribosome D. Tryptophan synthesis is regulated differently in eukaryotes and prokaryotes E. It is non-inducible _____Which of the following mutations may give rise to constitutive gene expression? A. Activator mutations B. Operator mutations C. RNA polymerase mutations D. Enhancer mutations _____The lac inducer enables transcription by binding to A. Activator B. Lactose C. RNA polymerases D. Repressor E. Operator _____ Which of the following is characteristic of prokaryotic mRNA? A. Polyadenlyation of the 3' end of mRNA B. Rapid turnover of mRNA C. Removal of introns to form mature message D. Formation of lariat structures E. Capping of the 5' mRNA terminus _____The corepressor of tryptophan biosynthesis is A. tRNATrp B. Tryptophan C. Tryptophanase D. Tryptophan attenuator _____ Which of the following is true regarding the machinery of translation? A. Initiation usually begins at an AUG codon B. Eukaryotes have nuclear ribosomes C. Polycistronic mRNA usually has a single ribosome binding site D. tRNAs released from the ribosome are degraded E. Termination is at inverted repeats _____The blastula is A. A stage in embryonic development marked by cell migration B. An infolded hollow ball of cells C. An unfertilized egg D. A ball of about 104 cells containing a cavity E. A fertilized egg with no cleavage divisions _____ An autonomous developmental restriction A. is determined by genetically programmed changes in the cells B. is imposed by the position of cells in the embryo C. is mediated by physical interaction between cells D. is mediated by morphogens _____ Mutations that cause cells to undergo developmental fates characteristic of other types of cells are called A. execution mutations B. transformation mutations C. transfection mutations D. Programmed cell death _____ Genes that function in the mother that are needed for development of the embryo are called A. zygotic genes B. developmental early genes C. gap genes D. maternal-effect genes _____ Genes that control early development through their expression in the embryo are called A. zygotic genes B. developmental early genes C. gap genes D. maternal-effect genes _____ The coordinate genes are maternal-effect genes that A. regulate expression of a small group of genes along the anterior-posterior axis B. determine the body plan at the level of segmentation C. determine the body plan at the level of parasegmentation D. establish polarity within the early oocyte _____ A molecule that participates directly in the control of growth and form during development is called a A. morphogen B. developer C. inducer D. co-repressor _____ A pedigree showing each cell division and indicating the terminal differentiated state of each cell is called a A. lineage diagram B. linkage map C. gene map D. impossible _____ A(n) ___ is a diagram of the insect blastoderm identifying the regions from which particular adult structures are derived. A. linkage map B. gene map C. fate-map D. expression map Short Answer (2 points each) The site of RNA polymerase binding on the DNA template is called the _______________________. The three nucleotides on a tRNA molecule that pair with the three nucleotides of a specific codon in mRNA are called the _______________________. A single mRNA transcript containing multiple genes is called _______________________. A series of linked bacterial genes whose expression is controlled by a single regulatory region usually involving polycistronic mRNA production is called an _______________________. A substance that interacts with a repressor protein to stimulate gene expression is called a(n) ________________________. The DNA sequence bound by repressor in a negatively regulated system is called the ________________________. The negative regulator of the lac operon is encoded by the ______________ gene and the positive regulator of the lac operon is the ________________________ complex. The diagram to the right depicts the result of an experiment in which a mRNA molecule (thick black line) from a human cell is hybridized to a fragment of DNA that includes the entire gene that produces the mRNA. Briefly explain why these molecules do not line up exactly. The image to the right shows the fate of two cells positioned at opposite ends of a developing embryo. Cell 1 has an anterior cell fate and cell 2 has a posterior fate. If the development of cell 1 into an anterior cell and cell 2 into a posterior cell is autonomous, what would happen if the position of these two cells was switched? The cartoon to the right depicts the lactose operon and associated regulatory factors. In this situation, the -galactosidase gene is not expressed because both the cAMP-CRP complex and the LacI protein (Lac repressor) are bound to the DNA. What does this tell you about the availability of glucose and lactose? Short essay (5 points) Describe either the process of transcription or the process of translation.