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need answers for this questions. The Question originally published by Garland Science in 2009. Please I need it tonight.;Attachment Preview;Chapter 7 & 8.pdf Download Attachment;CHAPTER 7;FROM DNA TO PROTEIN: HOW CELLS READ THE GENOME;2009 Garland Science Publishing;From DNA to RNA;7-1;RNA in cells differs from DNA in that ___________________.;(a);it contains the base uracil, which pairs with cytosine;(b);it is single-stranded and cannot form base pairs;(c);it is single-stranded and can fold up into a variety of structures;(d);the sugar ribose contains fewer oxygen atoms than does deoxyribose;7-2;Transcription is similar to DNA replication in that ___________________.;(a);an RNA transcript is synthesized discontinuously and the pieces are then;joined together;(b);it uses the same enzyme as that used to synthesize RNA primers during;DNA replication;(c);the newly synthesized RNA remains paired to the template DNA;(d);nucleotide polymerization occurs only in the 5-to-3 direction;7-3;For each of the following sentences, fill in the blanks with the best word or phrase;selected from the list below. Not all words or phrases will be used, use each word;or phrase only once.;For a cells genetic material to be used, the information is first;copied from the DNA into the nucleotide sequence of RNA in a;process called __________________. Various kinds of RNA are;produced, each with different functions.;molecules code for proteins, __________________ molecules act;as adaptors for protein synthesis, __________________ molecules;are integral components of the ribosome, and;molecules are important in the splicing of;RNA transcripts.;incorporation;mRNA;pRNA;translation;7-4;rRNA;snRNA;transcription;Match the following structures with their names.;transmembrane;tRNA;proteins;Figure Q7-4;7-5;Which of the following statements is false?;(a);A new RNA molecule can begin to be synthesized from a gene before the;previous RNA molecules synthesis is completed.;(b);If two genes are to be expressed in a cell, these two genes can be;transcribed with different efficiencies.;(c);RNA polymerase is responsible for both unwinding the DNA helix and;catalyzing the formation of the phosphodiester bonds between nucleotides.;(d);Unlike DNA, RNA uses a uracil base and a deoxyribose sugar.;7-6;Which one of the following is the main reason that a typical eucaryotic gene is;able to respond to a far greater variety of regulatory signals than a typical;procaryotic gene or operon?;(a);Eucaryotes have three types of RNA polymerase.;(b);Eucaryotic RNA polymerases require general transcription factors.;(c);The transcription of a eucaryotic gene can be influenced by proteins that;bind far from the promoter.;(d);Procaryotic genes are packaged into nucleosomes.;7-7;Match the following types of RNA with the main polymerase that transcribes;them.;7-8;List three ways in which the process of eucaryotic transcription differs from the;process of bacterial transcription.;7-9;For each of the following sentences, fill in the blanks with the best word or phrase;selected from the list below. Not all words or phrases will be used, each word or;phrase should be used only once.;In eucaryotic cells, general transcription factors are required for the;activity of all promoters transcribed by RNA polymerase II. The;assembly of the general transcription factors begins with the;binding of the factor __________________ to DNA, causing a;marked local distortion in the DNA. This factor binds at the DNA;sequence called the __________________ box, which is typically;located 25 nucleotides upstream from the transcription start site.;Once RNA polymerase II has been brought to the promoter DNA;it must be released to begin making transcripts. This release;process is facilitated by the addition of phosphate groups to the tail;of RNA polymerase by the factor __________________. It must;be remembered that the general transcription factors and RNA;polymerase are not sufficient to initiate transcription in the cell and;are affected by proteins bound thousands of nucleotides away from;the promoter. Proteins that link the distantly bound transcription;regulators to RNA polymerase and the general transcription factors;include the large complex of proteins called;the__________________. The packing of DNA into chromatin;also affects transcriptional initiation, and histone;is an enzyme that can render the DNA less;accessible to the general transcription factors.;activator;CAP;deacetylase;enhancer;7-10;lac;ligase;mediator;TATA;TFIIA;TFIID;TFIIH;You have a piece of DNA that includes the following sequence;5-ATAGGCATTCGATCCGGATAGCAT-3;3-TATCCGTAAGCTAGGCCTATCGTA-5;Which of the following RNA molecules could be transcribed from this piece of;DNA?;(a);(b);(c);(d);7-11;5-UAUCCGUAAGCUAGGCCUAUGCUA-3;5-AUAGGCAUUCGAUCCGGAUAGCAU-3;5-UACGAUAGGCCUAGCUUACGGAUA-3;none of the above;You have a segment of DNA that contains the following sequence;5-GGACTAGACAATAGGGACCTAGAGATTCCGAAA-3;3-CCTGATCTGTTATCCCTGGATCTCTAAGGCTTT-5;If you know that the RNA transcribed from this segment contains the following;sequence;5-GGACUAGACAAUAGGGACCUAGAGAUUCCGAAA3;Which of the following choices best describes how transcription occurs?;(a);The top strand is the template strand, RNA polymerase moves along this;strand from 5 to 3.;(b);The top strand is the template strand, RNA polymerase moves along this;strand from 3 to 5.;(c);The bottom strand is the template strand, RNA polymerase moves along;this strand from 5 to 3.;(d);The bottom strand is the template strand, RNA polymerase moves along;this strand from 3 to 5.;7-12;Which of the following molecules of RNA would you predict to be the most;likely to fold into a specific structure as a result of intramolecular base pairing?;(a);(b);(c);(d);7-13;5CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3;5UGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUG-3;5AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-3;5GGAAAAGGAGAUGGGCAAGGGGAAAAGGAGAUGGGCAAGG-3;Imagine that an RNA polymerase is transcribing a segment of DNA that contains;the following sequence;5-AGTCTAGGCACTGA-3;3-TCAGATCCGTGACT 5;A.;B.;7-14;If the polymerase is transcribing from this segment of DNA from left to;right, which strand (top or bottom) is the template?;What will be the sequence of that RNA (be sure to label the 5 and 3 ends;of your RNA molecule)?;The sigma subunit of bacterial RNA polymerase ___________________.;(a);contains the catalytic activity of the polymerase;(b);remains part of the polymerase throughout transcription;(c);recognizes promoter sites in the DNA;(d);recognizes transcription termination sites in the DNA;7-15;Which of the following might decrease the transcription of only one specific gene;in a bacterial cell?;(a);a decrease in the amount of sigma factor;(b);a decrease in the amount of RNA polymerase;(c);a mutation that introduced a stop codon into the DNA that precedes the;genes coding sequence;(d);a mutation that introduced extensive sequence changes into the DNA that;precedes the genes transcription start site;7-16;There are several reasons why the primase used to make the RNA primer for;DNA replication is not suitable for gene transcription. Which of the statements;below is not one of those reasons?;(a);Primase initiates RNA synthesis on a single-stranded DNA template.;(b);Primase can initiate RNA synthesis without the need for a base-paired;primer.;(c);Primase synthesizes only RNAs of about 520 nucleotides in length.;(d);The RNA synthesized by primase remains base-paired to the DNA;template.;7-17;You have a bacterial strain with a mutation that removes the transcription;termination signal from the Abd operon. Which of the following statements;describes the most likely effect of this mutation on Abd transcription?;(a);The Abd RNA will not be produced in the mutant strain.;(b);The Abd RNA from the mutant strain will be longer than normal.;(c);Sigma factor will not dissociate from RNA polymerase when the Abd;operon is being transcribed in the mutant strain.;(d);RNA polymerase will move in a backwards fashion at the Abd operon in;the mutant strain.;7-18;Transcription in bacteria differs from transcription in a eucaryotic cell because;(a);RNA polymerase (along with its sigma subunit) can initiate transcription;on its own;(b);RNA polymerase (along with its sigma subunit) requires the general;transcription factors to assemble at the promoter before polymerase can;begin transcription;(c);The sigma subunit must associate with the appropriate type of RNA;polymerase to produce mRNAs;(d);RNA polymerase must be phosphorylated at its C-terminal tail for;transcription to proceed;7-19;Which of the following does not occur before a eucaryotic mRNA is exported;from the nucleus?;(a);The ribosome binds to the mRNA.;(b);The mRNA is polyadenylated at its 3 end.;(c);(d);7-20;7-methyl-G is added in a 5 to 5 linkage to the mRNA.;RNA polymerase dissociates.;Use the numbers in the choices below to indicate where in the schematic diagram;of a eucaryotic cell (Figure Q7-20) those processes take place.;Figure Q7-20;1.;2.;3.;4.;5.;transcription;translation;RNA splicing;polyadenylation;RNA capping;7-21;Total nucleic acids are extracted from a culture of yeast cells and are then mixed;with resin beads to which the polynucleotide 5TTTTTTTTTTTTTTTTTTTTTTTTT-3 has been covalently attached. After a;short incubation, the beads are then extracted from the mixture. When you;analyze the cellular nucleic acids that have stuck to the beads, which of the;following is most abundant?;(a);DNA;(b);tRNA;(c);rRNA;(d);mRNA;7-22;Name three covalent modifications that can be made to an RNA molecule in;eucaryotic cells before the RNA molecule becomes a mature mRNA.;7-23;Which of the following statements about RNA splicing is false?;(a);Conventional introns are not found in bacterial genes.;(b);(c);(d);For a gene to function properly, every exon must be removed from the;primary transcript in the same fashion on every mRNA molecule produced;from the same gene.;Small RNA molecules in the nucleus perform the splicing reactions;necessary for the removal of introns.;Splicing occurs after the 5 cap has been added to the end of the primary;transcript.;7-24;The length of a particular gene in human DNA, measured from the start site for;transcription to the end of the protein-coding region, is 10,000 nucleotides;whereas the length of the mRNA produced from this gene is 4000 nucleotides.;What is the most likely reason for this difference?;7-25;Why is the old dogma one geneone protein not always true for eucaryotic;genes?;7-26;Is this statement true or false? Explain your answer.;Since introns do not contain protein coding information, they do not have;to be removed precisely (meaning, a nucleotide here and there should not;matter) from the primary transcript during RNA splicing.;7-27;You have discovered a gene (Figure Q7-27A) that is alternatively spliced to;produce several forms of mRNA in various cell types, three of which are shown;in Figure Q7-27B. The lines connecting the exons that are included in the mRNA;indicate the splicing. From your experiments, you know that protein translation;begins in exon 1. For all forms of the mRNA, the encoded protein sequence is the;same in the regions of the mRNA that correspond to exons 1 and 10. Exons 2 and;3 are alternative exons used in different mRNA, as are exons 7 and 8. Which of;the following statements about exons 2 and 3 is the most accurate? Explain your;answer.;Figure Q7-27;(a);(b);(c);(d);Exons 2 and 3 must have the same number of nucleotides.;Exons 2 and 3 must contain an integral number of codons (that is, the;number of nucleotides divided by 3 must be an integer).;Exons 2 and 3 must contain a number of nucleotides that when divided by;3, leaves the same remainder (that is, 0, 1, or 2).;Exons 2 and 3 must have different numbers of nucleotides.;From RNA to Protein;7-28;Which of the following statements about the genetic code is correct?;(a);All codons specify more than one amino acid.;(b);The genetic code is redundant.;(c);All amino acids are specified by more than one codon.;(d);All codons specify an amino acid.;NOTE: The following codon table is to be used for Problems Q7-29 to Q7-36, Q7-43;and Q7-47.;7-29;The piece of RNA below includes the region that codes the binding site for the;initiator tRNA needed in translation.;5-GUUUCCCGUAUACAUGCGUGCCGGGGGC-3;Which amino acid will be on the tRNA that is the first to bind to the A-site of the;ribosome?;(a);methionine;(b);arginine;(c);cystine;(d);valine;7-30;The following DNA sequence includes the beginning of a sequence coding for a;protein. What would be the result of a mutation that changed the C marked by an;asterisk to an A?;5-AGGCTATGAATGGACACTGCGAGCCC.;*;7-31;Which amino acid would you expect a tRNA with the anticodon 5-CUU-3 to;carry?;(a);lysine;(b);glutamic acid;(d);leucine;(d);phenylalanine;7-32;Which of the following pairs of codons might you expect to be read by the same;tRNA as a result of wobble?;(a);CUU and UUU;(b);GAU and GAA;(c);CAC and CAU;(d);AAU and AGU;7-33;Below is a segment of RNA from the middle of an mRNA.;5-UAGUCUAGGCACUGA-3;If you were told that this segment of RNA was part of the coding region of an;mRNA for a large protein, give the amino acid sequence for the protein that is;encoded by this segment of mRNA. Write your answer using the one-letter amino;acid code.;7-34;Below is the sequence from the 3 end of an mRNA.;5-CCGUUACCAGGCCUCAUUAUUGGUAACGGAAAAAAAAAAAAAA-3;If you were told that this sequence contains the stop codon for the protein encoded;by this mRNA, what is the anticodon on the tRNA in the P-site of the ribosome;when release factor binds to the A-site?;(a);5-CCA-3;(b);5-CCG-3;(c);5-UGG-3;(d);5-UUA-3;7-35;One strand of a section of DNA isolated from the bacterium E. coli reads;5-GTAGCCTACCCATAGG-3;A.;B.;C.;7-36;Suppose that an mRNA is transcribed from this DNA using the;complementary strand as a template. What will be the sequence of the;mRNA in this region (make sure you label the 5 and 3 ends of the;mRNA)?;How many different peptides could potentially be made from this;sequence of RNA, assuming that translation initiates upstream of this;sequence?;What are these peptides? (Give your answer using the one-letter amino;acid code.);A strain of yeast translates mRNA into protein inaccurately. Individual molecules;of a particular protein isolated from this yeast have variations in the first 11 amino;acids compared with the sequence of the same protein isolated from normal yeast;cells, as listed in Figure Q7-36. What is the most likely cause of this variation in;protein sequence?;Figure Q7-36;(a);(b);(c);(d);a mutation in the DNA coding for the protein;a mutation in the anticodon of the isoleucine tRNA (tRNAIle);a mutation in the isoleucyl-tRNA synthetase that decreases its ability to;distinguish between different amino acids;a mutation in the isoleucyl-tRNA synthetase that decreases its ability to;distinguish between different tRNA molecules;7-37;Which of the following statements is true?;(a);Ribosomes are large RNA structures composed solely of rRNA.;(b);Ribosomes are synthesized entirely in the cytoplasm.;(c);rRNA contains the catalytic activity that joins amino acids together.;(d);A ribosome binds one tRNA at a time.;7-38;Figure Q7-38A shows the stage in translation when an incoming aminoacyl-tRNA;has bound to the A-site on the ribosome. Using the components shown in Figure;Q7-38A as a guide, show on Figure Q7-38B and Q7-38C what happens in the;next two stages to complete the addition of the new amino acid to the growing;polypeptide chain.;Figure Q7-38;7-39;A poison added to an in vitro translation mixture containing mRNA molecules;with the sequence 5-AUGAAAAAAAAAAAAUAA-3 has the following effect;the only product made is a Met-Lys dipeptide that remains attached to the;ribosome. What is the most likely way in which the poison acts to inhibit protein;synthesis?;(a);It inhibits peptidyl transferase activity.;(b);It inhibits movement of the small subunit relative to the large subunit.;(c);It inhibits release factor.;(d);It mimics release factor.;7-40;In eucaryotes, but not in procaryotes, ribosomes find the start site of translation by;(a);binding directly to a ribosome-binding site preceding the initiation codon;(b);scanning along the mRNA from the 5 end;(c);recognizing an AUG codon as the start of translation;(d);binding an initiator tRNA;7-41;Which of the following statements about procaryotic mRNA molecules is false?;(a);A single procaryotic mRNA molecule can be translated into several;proteins.;(b);Ribosomes must bind to the 5 cap before initiating translation.;(c);mRNAs are not polyadenylated.;(d);Ribosomes can start translating an mRNA molecule before transcription is;complete.;7-42;Figure Q7-42 shows an mRNA molecule.;Figure Q7-42;A.;B.;Match the labels given in the list below with the label lines in Figure Q742.;(a);ribosome-binding site;(b);initiator codon;(c);stop codon;(d);untranslated 3 region;(e);untranslated 5 region;(f);protein-coding region;Is the mRNA shown procaryotic or eucaryotic? Explain your answer.;7-43;A mutation in the tRNA for the amino acid lysine results in the anticodon;sequence 5-UAU-3 (instead of 5-UUU-3). Which of the following aberrations;in protein synthesis might this tRNA cause? (Refer to the codon table provided;above Q7-29.);(a);read-through of stop codons;(b);substitution of lysine for isoleucine;(c);substitution of lysine for tyrosine;(d);substitution of lysine for phenylalanine;7-44;You have discovered a protein that inhibits translation. When you add this;inhibitor to a mixture capable of translating human mRNA and centrifuge the;mixture to separate polyribosomes and single ribosomes, you obtain the results;shown in Figure Q7-44. Which of the following interpretations is consistent with;these observations?;Figure Q7-44;(a);(b);(c);(d);The protein binds to the small ribosomal subunit and increases the rate of;initiation of translation.;The protein binds to sequences in the 5 region of the mRNA and inhibits;the rate of initiation of translation.;The protein binds to the large ribosomal subunit and slows down;elongation of the polypeptide chain.;The protein binds to sequences in the 3 region of the mRNA and prevents;termination of translation.;7-45;The concentration of a particular protein X in a normal human cell rises gradually;from a low point, immediately after cell division, to a high point, just before cell;division, and then drops sharply. The level of its mRNA in the cell remains fairly;constant throughout this time. Protein X is required for cell growth and survival;but the drop in its level just before cell division is essential for division to;proceed. You have isolated a line of human cells that grow in size in culture but;cannot divide, and on analyzing these mutants, you find that levels of X mRNA in;the mutant cells are normal. Which of the following mutations in the gene for X;could explain these results?;(a);the introduction of a stop codon that truncates protein X at the fourth;amino acid;(b);a change of the first ATG codon to CCA;(c);the deletion of a sequence that encodes sites at which ubiquitin can be;attached to the protein;(d);a change at a splice site that prevents splicing of the RNA;7-46;For each of the following sentences, fill in the blanks with the best word or phrase;selected from the list below. Not all words or phrases will be used, use each word;or phrase only once.;Once an mRNA is produced, its message can be decoded on;ribosomes. The ribosome is composed of two subunits: the;subunit, which catalyzes the formation of;the peptide bonds that link the amino acids together into a;polypeptide chain, and the __________________ subunit, which;matches the tRNAs to the codons of the mRNA. During the chain;elongation process of translating an mRNA into protein, the;growing polypeptide chain attached to a tRNA is bound to the;-site of the ribosome. An incoming;aminoacyl-tRNA carrying the next amino acid in the chain will;bind to the __________________-site by forming base pairs with;the exposed codon in the mRNA. The;enzyme catalyzes the formation of a new peptide bond between the;growing polypeptide chain and the newly arriving amino acid. The;end of a protein-coding message is signaled by the presence of a;stop codon, which binds the __________________ called release;factor. Eventually, most proteins will be degraded by a large;complex of proteolytic enzymes called the __________________.;A;central;DNA;E;large;7-47;medium;P;peptidyl transferase;polymerase;protein;proteasome;RNA;small;T;ubiquitin;After treating cells with a mutagen, you isolate two mutants. One carries alanine;and the other carries methionine at a site in the protein that normally contains;valine. After treating these two mutants again with mutagen, you isolate mutants;from each that now carry threonine at the site of the original valine (see Figure;Q7-47). Assuming that all mutations caused by the mutagen are due to single;nucleotide changes, deduce the codons that are used for valine, alanine;methionine, and threonine at the affected site. (Refer to the codon table;provided above Q7-29.);Figure Q7-47;7-48;Which of the following methods is not used by cells to regulate the amount of a;protein in the cell?;(a);Genes can be transcribed into mRNA with different efficiencies.;(b);Many ribosomes can bind to a single mRNA molecule.;(c);(d);7-49;Proteins can be tagged with ubiquitin, marking them for degradation.;Nuclear pore complexes can regulate the speed at which newly;synthesized proteins are exported from the nucleus into the cytoplasm.;Which of the following statements about the proteasome is false?;(a);Ubiquitin is a small protein that is covalently attached to proteins to mark;them for delivery to the proteasome.;(b);Proteases reside in the central cylinder of a proteasome.;(c);Misfolded proteins are delivered to the proteasome, where they are;sequestered from the cytoplasm and can attempt to refold.;(d);The protein stoppers that surround the central cylinder of the proteasome;use the energy from ATP hydrolysis to move proteins into the proteasome;inner chamber.;RNA and the Origins of Life;7-50;Which of the following molecules is thought to have arisen first during evolution?;(a);protein;(b);DNA;(c);RNA;(d);All came to be at the same time.;7-51;According to current thinking, the minimum requirement for life to have;originated on Earth was the formation of a _______________.;(a);molecule that could provide a template for the production of a;complementary molecule;(b);double-stranded DNA helix;(c);molecule that could direct protein synthesis;(d);molecule that could catalyze its own replication;7-52;Ribozymes catalyze which of the following reactions?;(a);DNA synthesis;(b);transcription;(c);RNA splicing;(d);protein hydrolysis;7-53;You are studying a disease that is caused by a virus, but when you purify the virus;particles and analyze them you find they contain no trace of DNA. Which of the;following molecules are likely to contain the genetic information of the virus?;(a);high-energy phosphate groups;(b);RNA;(c);lipids;(d);carbohydrates;7-54;Give a reason why DNA makes a better material than RNA for the storage of;genetic information, and explain your answer.;How We Know: Cracking the Genetic Code;7-55;You have discovered an alien life form that surprisingly uses DNA as its genetic;material, makes RNA from DNA, and reads the information from RNA to make;protein using ribosomes and tRNAs, which read triplet codons. Because it is your;job to decipher the genetic code for this alien, you synthesize some artificial RNA;molecules and examine the protein products produced from these RNA molecules;in a cell-free translation system using purified alien tRNAs and ribosomes. You;obtain the results shown in Table Q7-55.;Table Q7-55;From this information, which of the following peptides can be produced from;poly UAUC?;(a);Ile-Phe-Val-Tyr;(b);Tyr-Ser-Phe-Ala;(c);Ile-Lys-His-Tyr;(d);Cys-Pro-Lys-Ala;7-56;An extraterrestrial organism (ET) is discovered whose basic cell biology seems;pretty much the same as that of terrestrial organisms except that it uses a different;genetic code to translate RNA into protein. You set out to break the code by;translation experiments using RNAs of known sequence and cell-free extracts of;ET cells to supply the necessary protein-synthesizing machinery. In experiments;using the RNAs below, the following results were obtained when the 20 possible;amino acids were added either singly or in different combinations of two or three;RNA 1: 5-GCGCGCGCGCGCGCGCGCGCGCGCGCGC-3;RNA 2: 5-GCCGCCGCCGCCGCCGCCGCCGCCGCCGCC-3;Using RNA 1, a polypeptide was produced only if alanine and valine were added;to the reaction mixture. Using RNA 2, a polypeptide was produced only if leucine;and serine and cysteine were added to the reaction mixture. Assuming that protein;synthesis can start anywhere on the template, that the ET genetic code is;nonoverlapping and linear, and that each codon is the same length (like the;terrestrial triplet code), how many nucleotides does an ET codon contain?;(a);2;(b);3;(c);4;(d);5;(e);6;7-57;NASA has discovered an alien life form. You are called in to help NASA;scientists to deduce the genetic code for this alien. Surprisingly, this alien life;form shares many similarities with life on Earth: this alien uses DNA as its;genetic material, makes RNA from DNA, and reads the information from RNA to;make protein using ribosomes and tRNAs. Even more amazing, this alien uses the;same 20 amino acids, like the organisms found on Earth, and also codes for each;amino acid by a triplet codon. However, the scientists at NASA have found that;the genetic code used by the alien life form differs from that used by life on Earth.;NASA scientists drew this conclusion after creating a cell-free protein synthesis;system from alien cells and adding an mRNA made entirely of uracil (poly U).;They found that poly U directs the synthesis of a peptide containing only glycine.;NASA scientists have synthesized a poly AU mRNA and observe that it codes for;a polypeptide of alternating serine and proline amino acids. From these;experiments, can you determine which codons code for serine and proline?;Explain.;Bonus question. Can you propose a mechanism for how the aliens physiology is;altered so that it uses a different genetic code from life on Earth, despite all the;similarities?;CHAPTER 8;CONTROL OF GENE EXPRESSION;2009 Garland Science Publishing;An Overview of Gene Expression;8-1;The distinct characteristics of different cell types in a multicellular organism;result mainly from the differential regulation of the _________________.;(a);replication of specific genes;(b);transcription of genes transcribed by RNA polymerase II;(c);transcription of housekeeping genes;(d);packing of DNA into nucleosomes in some cells and not others;8-2;The human genome encodes about 24,000 genes. Approximately how many genes;does the typical differentiated human cell express at any one time?;(a);24,000all of them;(b);between 21,500 and 24,000at least 90% of the genes;(c);between 5000 and 15,000;(d);less than 2500;8-3;Which of the following statements about differentiated cells is true?;(a);Cells of distinct types express nonoverlapping sets of transcription factors.;(b);Once a cell has differentiated, it can no longer change its gene expression.;(c);Once a cell has differentiated, it will no longer need to transcribe RNA.;(d);Some of the proteins found in differentiated cells are found in all cells of a;multicellular organism.;8-4;Investigators performed nuclear transplant experiments to determine whether;DNA is altered irreversibly during development. Which of the following;statements about these experiments is true?;(a);Because the donor nucleus is taken from an adult animal, the;chromosomes from the nucleus must undergo recombination with the;DNA in the egg for successful development to occur.;(b);The embryo that develops from the nuclear transplant experiment is;genetically identical to the donor of the nucleus.;(c);The meiotic spindle of the egg must interact with the chromosomes of the;injected nuclei for successful nuclear transplantation to occur.;(d);Although nuclear transplantation has been successful in producing;embryos in some mammals with the use of foster mothers, evidence of;DNA alterations during differentiation has not been obtained for plants.;8-5;In principle, a eucaryotic cell can regulate gene expression at any step in the;pathway from DNA to the active protein. Place the types of control listed below at;the appropriate places on the diagram in Figure Q8-5.;Figure Q8-5;A.;B.;C.;D.;translation control;transcriptional control;RNA processing control;protein activity control;How Transcriptional Switches Work;8-6;Fill in the blanks with the best word or phrase selected from the list below. Not all;words or phrases will be used, each word or phrase should be used only once.;The genes of a bacterial __________________ are transcribed into;a single mRNA. Many bacterial promoters contain a region known;as a(n) __________________, to which a specific transcription;regulator binds. Genes in which transcription is prevented are said;to be __________________. The interaction of small molecules;such as tryptophan, with __________________ DNA-binding;proteins, such as the tryptophan repressor, regulates bacterial;genes. Genes that are being __________________ expressed are;being transcribed all the time.;allosteric;constitutively;induced;8-7;negatively;operator;operon;positively;promoter;repressed;Which of the following statements about transcriptional regulators is false?;(a);Transcriptional regulators usually interact with the sugar-phosphate;backbone on the outside of the double helix to determine where to bind on;the DNA helix.;(b);Transcriptional regulators will form hydrogen bonds, ionic bonds, and;hydrophobic interactions with DNA.;(c);The DNA-binding motifs of transcriptional regulators usually bind in the;major groove of the DNA helix.;(d);The binding of transcriptional regulators generally does not disrupt the;hydrogen bonds that holds the double helix together.;8-8;Operons ___________________________.;(a);are commonly found in eucaryotic cells;(b);are transcribed by RNA polymerase II;(c);contain a cluster of genes transcribed as a single mRNA;(d);can only be regulated by gene activator proteins;8-9;The tryptophan operator ___________________________.;(a);is an allosteric protein;(b);binds to the tryptophan repressor when the repressor is bound to;tryptophan;(c);is required for production of the mRNA encoded by the tryptophan operon;(d);is important for the production of the tryptophan repressor;8-10;Which of the following statements about the Lac operon is false?;(a);The Lac repressor binds when lactose is present in the cell.;(b);Even when the CAP activator is bound to DNA, if lactose is not present;the Lac operon will not be transcribed.;(c);The CAP activator can only bind DNA when it is bound to cAMP.;(d);The Lac operon only produces RNA when lactose is present and glucose is;absent.;8-11;You are interested in examining the regulation of the gene that encodes an;enzyme, Tre-ase, important in metabolizing trehalose into glucose in bacteria.;Trehalose is a disaccharide formed of two glucose units. It is known that two;DNA binding proteins, TreA and TreB, are important for binding to the promoter;of the Tre-ase gene and are involved in regulating the transcription of the Tre-ase;gene: TreA binds to the A site in the promoter region, and TreB binds to the;B site. You make mutations in the TreA and TreB genes to create cells lacking;these genes, observe what happens to transcription of the Tre-ase gene, and obtain;the results in Table Q8-11.;Table Q8-11;A.;B.;What is the role for TreA in controlling Tre-ase expression? Explain.;What is the role for TreB in controlling Tre-ase expression? Explain.;C.;From these data, what do you predict will happen to Tre-ase transcription;(compared with that in normal cells) in the presence of trehalose if you;were to create a version of the TreA protein that will constitutively bind to;the A site in the Tre-ase promoter?;Note: Questions 8-12 to 8-15 use the following information and the data in Table;Q8-12. These questions may be used independently, or as a group.;You are interested in examining the Psf gene. It is known that Psf is normally produced;when cells are exposed to high levels of both calcium (Ca2+) and magnesium (Mg2+).;MetA, MetB, and MetC are important for binding to the promoter of the Psf gene and are;involved in regulating its transcription. MetA binds to the A site in the promoter;region, MetB to the B site, and MetC to


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