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bio
| Question | Answer |
|---|---|
| What does the operon model attempt to explain? | A, the coordinated control of gene expression in bacteria |
| The role of a metabolite that controls a repressible operon is to | E, bind to the repress or protein and activate it |
| The tryptophan operon is a repressible operon that is | E, turned off whenever tryptophan is added to the growth medium |
| This protein is produced by a regulatory gene | D, repressor |
| A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA: | promoter |
| A lack of this nonprotein molecule would result in the inability of the cell to ʺturn offʺ genes: | Corepressor |
| When this is taken up by the cell, it binds to the repressor so that the repressor no longer binds to the operator: | Inducer |
| A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in | A, continuous transcription of the structural gene controlled by that regulator |
| The lactose operon is likely to be transcribed when | the cyclic AMP and lactose levels are both high within the cell |
| Transcription of the structural genes in an inducible operon | starts when the pathway's substrate is present |
| How does active CAP induce expression of the genes of the lactose operon? | it stimulates the binding of RNA polymerase to the promoter |
| For a repressible operon to be transcribed, which of the following must occur? | RNA polymerase must bind to the promoter, and the repressor must be inactive |
| Allolactose induces the synthesis of the enzyme lactase. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell? | allolactose binds to the repressor protein |
| Altering patterns of gene expression in prokaryotes would most likely serve the organismʹs survival in which of the following ways? | allowing the organism to adjust to changes in environmental conditions |
| In response to chemical signals, prokaryotes can do which of the following? | alter the level of production of various enzymes |
| Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the promoter for the lac operon to the region between the beta galactosidase gene and the permease | beta galactosidase will be produced |
| If glucose is available in the environment of E. coli, the cell responds with very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would you expect would then be a measurable effect? | increased concentrations of sugars such as arabinose in the cell |
| Muscle cells and nerve cells in one species of animal owe their differences in structure to | having different genes expressed |
| Which of the following mechanisms is (are) used to coordinately control the expression of multiple, related genes in eukaryotic cells? | organization of the genes into clusters, with local chromatin structures influencing the expression of all the genes at once |
| If you were to observe the activity of methylated DNA, you would expect it to | have turned off or slowed down the process of transcription |
| Genomic imprinting, DNA methylation, and histone acetylation are all examples of | D, epigenetic phenomena |
| Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA? | 1.5% |
| Two potential devices that eukaryotic cells use to regulate transcription are | , DNA methylation and histone acetylation |
| In both eukaryotes and prokaryotes, gene expression is primarily regulated at the level of | transcription |
| In eukaryotes, transcription is generally associated with | both euchromatin and histone acetylation |
| A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, is expressed strongly, but in the fifth there is no expression at all. | A, a transgene integrated into a heterochromatic region of the genome |
| During DNA replication, | methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication |
| Eukaryotic cells can control gene expression by which of the following mechanisms? | A, histone acetylation of nucleosomes |
| In eukaryotes, general transcription factors | bind to other proteins or to a sequence element within the promoter called the TATA box |
| This binds to a site in the DNA far from the promoter to stimulate transcription: | activator |
| This can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA: | repressor |
| This is the site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3ʹ end of the transcript: | terminator |
| Steroid hormones produce their effects in cells by | binding to intracellular receptors and promoting transcription of specific genes |
| A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. this procedure in Drosophila, she was successful increasing phosphorylation of amino acids to methylated | decreased chromatin concentration |
| A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. | inactivation of the selected genes |
| A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. She decreasing methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. | abnormalities of mouse embryos |
| Transcription factors in eukaryotes usually have DNA binding domains as well as other domains also specific for binding. In general, which of the following would you expect many of them to be able to bind? | other transcription factors |
| Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following? | eukaryotic exons may be spliced in alternative patterns |
| Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell? | removal of the 5' cap |
| Which of the following is most likely to have a small protein called ubiquitin attached to it? | a cyclin that usually acts in G1, now that the cell is in G2 |
| The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called | RNA interference |
| At the beginning of this century there was a general announcement the sequencing of the human genome and the genomes of many other multicellular eukaryotes. expressed by many number of protein-coding sequences is much smaller than they had expected. | non-protein coding DNA that is transcribed into several kinds of small RNAs with biological function |
| Which of the following best describes siRNA? | a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA |
| One of the hopes for use of recent knowledge gained about non-coding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs? | targeting siRNA to disable the expression of an allele associated with autosomal dominant disease |
| Which of the following describes the function of an enzyme known as Dicer | it trims small double-stranded RNAs into molecules that can block translation |
| In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates, and the centromere is abnormally formed from chromatin. Which of the following is most likely to occur? | centromeres will be euchromatic rather than heterochromatic and the cells will soon die in culture |
| Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained? | changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible |
| You are given an experimental problem involving control of a geneʹs expression in the embryo of a particular species. One of your first questions is whether the geneʹs expression is controlled at the level of transcription or translation. | you measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same |
| In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to | nonidentical genes that produce different versions of globins during development |
| The process of cellular differentiation is a direct result of | differential gene expression |
| The fact that plants can be cloned from somatic cells demonstrates that | differentiated cells retain all the genes of the zygote |
| A cell that remains entirely flexible in its developmental possibilities is said to be | totipotent |
| Differentiation of cells is not easily reversible because it involves | frameshift mutations and inversions |
| In animals, embryonic stem cells differ from adult stem cells in that | embryonic stem cells are totipotent, and adult stem cells are pluripotent |
| Which of the following statements is true about stem cells? | stem cells can differentiate into specialized cells |
| What is considered to be the first evidence of differentiation in the cells of an embryo? | the occurrence of mRNAs for the production of tissue-specific proteins |
| In most cases, differentiation is controlled at which level? | transcription |
| Which of the following serve as sources of developmental information? | cytoplasmic determinants such as mRNA and proteins produced before fertilization |
| The MyoD protein | is a transcription factor that binds to and activates the transcription of muscle-related genes |
| The gene for which protein would most likely be expressed as a result of MyoD activity? | myosin |
| The general process that leads to the differentiation of cells is called | determination |
| Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development? | pattern formation |
| Which of the following is established prior to fertilization in Drosophila eggs? | the anterior-posterior and dorsal-ventral axes |
| The product of the bicoid gene in Drosophila provides essential information about | the anterior-posterior axis |
| If a Drosophila female has a homozygous mutation for a maternal effect gene, | all of her offspring will show the mutant phenotype, regardless of their genotype |
| Mutations in these genes lead to transformations in the identity of entire body parts: | homeotic genes |
| These genes are expressed by the mother, and their products are deposited into the developing egg | egg-polarity genes |
| These genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo | segmentation genes |
| These genes form gradients and help establish the axes and other features of an embryo: | morphogens |
| Gap genes and pair-rule genes fall into this category: | segmentation genes |
| The product of the bicoid gene in Drosophila could be considered a(n) | cytoplasmic determinant |
| The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur? | anterior structures would form in both sides of the embryp |
| What do gap genes, pair-rule genes, segment polarity genes, and homeotic genes all have in common? | their products act as transcription factors |
| Which of the following statements describes proto-oncogenes? | they can code for proteins associated with cell growth |
| Which of the following is characteristic of the product of the p53 gene? | it is an activator for other genes |
| Tumor suppressor genes | can encode proteins that promote DNA repair or cell-cell adhesion |
| The incidence of cancer increases dramatically in older humans because | the longer we live, the more mutations we accumulate |
| The cancer-causing forms of the Ras protein are involved in which of the following processes? | relaying a signal from a growth factor receptor |
| Forms of the ras protein found in tumors usually cause which of the following? | growth factor signaling to be hyperactive |
| A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer? | A, colorectal only |
| Which of the following can contribute to the development of cancer? | E, all of the above |
| One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure | inherited inability to repair UV-induced mutation |
| One of the human leukemias, called CML (chronic myelogenous leukemia) is associated with a chromosomal translocation between chromosomes 9 and 22 in somatic cells of bone marrow. | the translocation requires breaks in both chromosomes 9 and 22, followed by fusion between the reciprocal pieces |
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26ruthie