AP BIO CH. 18 – Flashcards

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question
The role of a metabolite that controls a repressible operon is to bind to the ___ protein and ___ it.
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Repressor, activate
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The tryptophan operon is a repressible operon that is turned ___ whenever ___ is added to the growth medium.
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Off, tryptophan
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Which of the following is a protein produced by a regulatory gene?
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repressor
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A lack of which molecule would result in the cell's inability to "turn off" genes?
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Corepressor
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Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?
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Inducer
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Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?
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Inducer
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A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in ___ ___ of the structural gene controlled by that ___.
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continuous transcription, regulator
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The lactose operon is likely to be transcribed when the ___ ___ and ___ ___ are both ___ within the cell.
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cyclic AMP, lactose levels, high
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Transcription of the structural genes in an inducible operon ___ when the pathway's ___ is present.
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Starts, substrate
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For a repressible operon to be transcribed, what must occur is that ___ ___ must bind to the ___, and the repressor must be ___.
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RNA polymerase, promoter, inactive
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Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. What occurs when the lactose enters the cell is that Allolactose binds to the ___ ___.
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repressor protein
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Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in allowing the organism to ___ to changes in ___ conditions
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Adjust, environmental
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In response to chemical signals, prokaryotes can alter the level of production of various ___.
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Enzymes
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If glucose is available in the environment of E. coli, the cell responds with a very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. An expected measurable effect would be ___ concentrations of ___ such as arabinose in the cell
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Increased, sugars
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In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP is a ___ in glucose and increase in ___.
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Decrease, cAMP
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There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. What would characterize such a mutant is that It cannot ___ to the ___.
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Bind, inducer
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The mechanism that is used to coordinate the expression of multiple, related genes in eukaryotic cells is that Genes are organized into ___, with local ___ structures influencing the __ of all the genes at once.
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Clusters, chromatin, expression
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If you were to observe the activity of methylated DNA, you would expect it to have ___ ___ or ___ ___ the process of ___.
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Turned off, slowed down, transcription
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Genomic imprinting, DNA methylation, and histone acetylation are all examples of
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epigenetic phenomena
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When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. The processes contributing to this dynamic activity are ___ and ___ of ___ tails
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Methylation, phosphorylation, histone
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Two potential devices that eukaryotic cells use to regulate transcription are DNA ___ and histone ___.
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methylation, modification
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During DNA replication, methylation of the DNA is maintained because methylation ___ act at DNA sites where one strand is already methylated and thus correctly methylates ___ strands after replication.
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Enzymes, daughter
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In eukaryotes, general transcription factors bind to other ___ or to a sequence element within the promoter called the ___ ___.
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proteins, TATA box
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Steroid hormones produce their effects in cells by ___ to intracellular receptors and promoting ___ of specific genes.
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binding, transcription
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Transcription factors in eukaryotes usually have DNA binding domains as well as other domains that are also specific for binding. In general, which of the following would you expect many of them to be able to bind?
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other transcription factors
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Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because Eukaryotic ___ may be ___ in alternative patterns.
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Exons, spliced
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The following experimental procedures most likely to hasten mRNA degradation in a eukaryotic cell is the ___ of the 5' ___.
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Removal, cap
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Of the following, the most likely to have a small protein called ubiquitin attached to it is a ___ that usually acts in G₁, now that the cell is in G₂
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Cyclin
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In prophase I of meiosis in female Drosophila, studies have shown that there is phosphorylation of an amino acid in the tails of histones of gametes. A mutation in flies that interferes with this process results in sterility. The most likely hypothesis is that Histone tail ___ prohibits chromosome __.
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phosphorylation, condensation
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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
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RNA interference
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At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed by many that the number of protein-coding sequences was much smaller than they had expected. What could account for most of the rest is non-___-coding DNA that is transcribed into several kinds of small RNAs ___ biological function
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Protein, with
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Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and block expression of some transposons. These are known as
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piRNA
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What best describes siRNA is a short ___-stranded RNA, one of whose strands can complement and ___ a sequence of mRNA
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Double, inactivate
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One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, what you would expect to gain most from RNAs is ___ siRNAs to disable the expression of an allele associated with autosomal ___ disease
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targeting, dominant
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What describes the function of an enzyme known as Dicer is that It ___ small double-stranded RNAs into molecules that can block __.
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trims, translation
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In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates so that the centromere is abnormally formed from chromatin. What is most likely to occur is that __ will be euchromatic rather than heterochromatic and the cells will soon ___ in culture.
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Centromeres, die
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Since Watson and Crick described DNA in 1953, what might best explain why the function of small RNAs is still being explained is that Changes in ___ as well as our ability to determine how much of the DNA is expressed have now made this possible.
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Technology
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You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of your first questions is whether the gene's expression is controlled at the level of transcription or translation. What might best give you an answer is that You ___ the quantity of the appropriate pre-mRNA in various cell types and find they are all the ___.
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measure, same
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In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to ___ genes that produce different ___ of globins during development.
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nonidentical, versions
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The fact that plants can be cloned from somatic cells demonstrates that ___ cells retain all the genes of the ___.
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differentiated, zygote
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In animals, embryonic stem cells differ from adult stem cells in that embryonic stem cells are ___, and adult stem cells are ___.
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totipotent, pluripotent
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What is considered to be the first evidence of differentiation in the cells of an embryo is the occurrence of ___s for the production of ___-specific proteins
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mRNA, tissue
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Embryonic lethal mutations result in Phenotypes that are never ___/hatched.
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Born
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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?
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Pattern formation
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The product of the bicoid gene in Drosophila provides essential information about the
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anterior posterior axis
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If a Drosophila female has a homozygous mutation for a maternal effect gene, ___ of her offspring will show the mutant phenotype, regardless of their ___.
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All, genotype
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Mutations in which of the following genes lead to transformations in the identity of entire body parts?
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Homeotic genes
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Which of the following genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo?
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Segmentation genes
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Gap genes and pair-rule genes fall into which of the following categories?
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Segmentation genes
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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, what would occur is that ___ structures would form in both sides of the embryo.
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Anterior
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What gap genes, pair-rule genes, segment polarity genes, and homeotic genes all have in common is that Their products act as ___ ___.
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transcription factors
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The statement that describes proto-oncogenes is that They can code for ___ associated with cell ___.
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Proteins, growth
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A characteristic of the product of the p53 gene is that It is an __ for other genes.
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activator
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Tumor-suppressor genes can encode proteins that promote DNA ___ or cell-cell ___.
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repair, adhesion
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BRCA1 and BRCA2 are considered to be tumor-suppressor genes because their ___ products participate in ___ of DNA damage.
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Normal, repair
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The cancer-causing forms of the Ras protein are involved in the following process of ___ a signal from a growth factor ___.
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relaying, receptor
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Forms of the Ras protein found in tumors usually cause a ___ factor signaling to be ___.
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Growth, hyperactive
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A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?
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Colorectal only
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In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. At this point, the embryo is characterized as nuclei in the ___ that has not undergone ___.
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cortex, cytokinesis
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In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. The four sequestered cells at one end are most probably destined to become the ___ cells of the adult.
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Germ
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In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. Formation of the pole cells (the four sequestered cells) demonstrates the role of ___ effect genes.
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Maternal
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In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. The next step after the embryo is formed would be ___ of the nuclei in ___, forming a single layer over the surface.
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Enclosure, membranes
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In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. The developmental stages described for Drosophila illustrate
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A hierarchy of gene expression
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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 gene, what's likely is that ___ galactosidase will be produced.
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Beta
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Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome If she moves the operator to the far end of the operon (past the transacetylase gene), what would likely occur when the cell is exposed to lactose is that The ___ genes will be ___ continuously.
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Structural, transcribed
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Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome If she moves the repressor gene (lac I), along with its promoter, to a position at some several thousand base pairs away from its normal position, you would expect to occur that The ___ operon will function ___.
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Lac, normally
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Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome If she moves the operator to a position upstream from the promoter, what would occur is that The ___ operon will be expressed ___.
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Lac, continuously
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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, the transgene is expressed strongly, but in the fifth there is no expression at all. What is a likely explanation for the lack of transgene expression in the fifth cell line is that A __ integrated into a ___ region of the genome.
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Transgene, heterochromatic
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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, the transgene is expressed strongly, but in the fifth there is no expression at all. Of the lines that express the transgene, one is transcribed but not translated. What is a likely explanation is that there is no ___ in any frame.
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AUG
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A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. The result she would most likely see is ___ chromatin condensation
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Decreased
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A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments she succeeded in decreasing methylation of histone tails. The result she would most likely see is ___ chromatin condensation
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Increased
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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. The result she would most likely see is ___ of the selected genes
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Inactivation
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A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. She tried decreasing the amount of methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. The result she would most likely see is ___ of mouse embryos
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Absnormalities
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A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. Within the first quarter hour, the researcher sees that the intact RNA is found in the cells. After 3 hours, she is not surprised to find that ___ enzyme has reduced it to smaller ___-stranded pieces.
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Dicer, double
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A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. Some time later, she finds that the introduced strand separates into single-stranded RNAs, one of which is degraded. This enables the remaining strand to ___ to ___ regions of target mRNAs
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Bind, complementary
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A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. In addition, she finds the other evidence of this single-stranded RNA piece's activity is that the rate of ___ of the ___ to be translated from the target mRNA is reduced.
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Accumulation, polypeptide
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A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method. The researcher in question measures the amount of new polypeptide production in embryos from 2—8 hours following fertilization and the results show a steady and significant rise in polypeptide concentration over that time. The researcher concludes that the ___ new polypeptides are due to ___ of maternal mRNAs.
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Resulting, translation
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A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method. The researcher continues to study the reactions of the embryo to these new proteins and you hypothesize that he is most likely to see (while embryonic genes are still not being expressed) ___ ___ (anterior → posterior, etc.) begin to be determined.
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Spatial axes
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The researcher measures the concentration of the polypeptides from different regions in the early embryo and finds the following pattern (darker shading = greater concentration): SEE IMAGE His most logical assumption would be that The substance is produced in region _ and diffuses toward region _.
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1,5
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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, patients soon succumb to numerous skin cancers. What best describes this phenomenon is an __ inability to repair __-induced mutation
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Inherited, UV
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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, patients soon succumb to numerous skin cancers. Given the damage caused by UV, the kind of gene affected in those with XP is one whose product is involved with the ability to ___ single-strand damage and ___ it.
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Excise, replace
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A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. Two children are born from the same parents. Child one inherits a predisposition to retinoblastoma (one of the mutations) and child two does not. However, both children develop the retinoblastoma. You would expect an ___ age of onset in child __.
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Earlier, one
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A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. In colorectal cancer, several genes must be mutated in order to make a cell a cancer cell, supporting Knudsen's hypothesis. The kinds of genes you would expect to be mutated would be genes involved in control of the ___ ___.
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Cell cycle
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A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. Knudsen and colleagues also noted that persons with hereditary retinoblastoma that had been treated successfully lived on but then had a higher frequency of developing osteosarcomas (bone cancers) later in life. This provided further evidence of their theory because ___ of the mutations involved in retinoblastoma is also one of the ___ involved in osteosarcoma.
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One, changes
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A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. 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. What allows CML to provide further evidence of this multistep nature of cancer is that The translocation requires ___ in both chromosomes 9 and 22, followed by ___ between the reciprocal pieces.
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Breaks, fusion
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Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. In areas of the world in which malaria is endemic, notably in sub-Saharan Africa, EBV can cause Burkitt's lymphoma in children, which is usually associated with large tumors of the jaw. What is consistent with these findings is that Malarial ___ of the immune system prevents an individual from making EBV ___.
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Response, antibodies
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Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. In a different part of the world, namely in parts of southeast Asia, the same virus is associated with a different kind of cancer of the throat. The most probable is that viral infection is correlated with a different ___ reaction.
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immunological
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Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. A very rare human allele of a gene called XLP, or X-linked lymphoproliferative syndrome, causes a small number of people from many different parts of the world to get cancer following even childhood exposure to EBV. Given the previous information, what might be going on is that They must be unable to mount an ___ ___ to EBV.
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Immune response
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Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. What must characterize the XLP population is that They must all be _ with affected ___ relatives.
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Males, female
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If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then the ___ ___ acts as a ___.
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Amino acid, corepressor
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Muscle cells differ from nerve cells mainly because they ___ different genes.
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Express
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The functioning of enhancers is an example of ___ control of gene ___.
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transcriptional, expression
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Cell differentiation always involves the production of ___-specific proteins, such as muscle __.
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Tissue, actin
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An example of post-transcriptional control of gene expression is the __ of introns and alternative __ of exons
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Removal, splicing
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What would occur if the repressor of an inducible operon were mutated so it could not bind the operator is ___ transcription of the ___'s genes
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continuous, operon
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Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene ___ leads to formation of ___ structures.
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Normally, head
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A statements about the DNA in one of your brain cells that is true is that It is the ___ as the DNA in one of your ___ cells.
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Same, heart
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Within a cell, the amount of protein made using a given mRNA molecule depends partly on the ___ at which the mRNA is ___.
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Rate, degraded
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Proto-oncogenes can change into oncogenes that cause cancer. What best explains the presence of these potential time bombs in eukaryotic cells is that Proto-oncogenes normally help regulate ___ __.
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Cell division
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