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All Textbook Solutions for Biology (MindTap Course List)
15TYU16TYUWrite a summary reaction for aerobic respiration that shows which reactant becomes oxidized and which becomes reduced.1C2C2LO3LOAdd up the energy captured (as ATP, NADH, and FADH2) in each stage of aerobic respiration.5LO6LO1C2CWhat are the roles of NAD+, FAD, and oxygen in aerobic respiration?4CSummarize how the products of protein and lipid catabolism enter the same metabolic pathway that oxidizes glucose.1C2C3CCompare and contrast anaerobic respiration and fermentation. Include the mechanism of ATP formation, the final electron acceptor, and the end products.What is the fate of hydrogen atoms removed from glucose during glycolysis when oxygen is present in muscle cells? How does it compare with the fate of hydrogen atoms removed from glucose when the amount of available oxygen is insufficient to support aerobic respiration?What accounts for the ATP yield of fermentation being only a tiny fraction of the yield from aerobic respiration?Is chemiosmosis involved in fermentation? in anaerobic respiration?A chemical process during which a substance gains electrons and energy is called (a) oxidation (b) oxidative phosphorylation (c) deamination (d) reduction (e) dehydrogenationThe reactions of _____ take place within the cytosol of eukaryotic cells. (a) glycolysis (b) oxidation of pyruvate (c) the citric acid cycle (d) chemiosmosis (e) the electron transport chainBefore pyruvate enters the citric acid cycle, it is decarboxylated, oxidized, and combined with coenzyme A, forming acetyl CoA, carbon dioxide, and one molecule of (a) NADH (b) FADH2 (c) ATP (d) ADP (e) C6H12O6In the first step of the citric acid cycle, an acetyl group from acetyl CoA reacts with oxaloacetate to form (a) pyruvate (b) citrate (c) NADH (d) ATP (e) CO2Which of the following is the major source of electrons that flow through the mitochondrial electron transport chain? (a) H2O (b) ATP (c) NADH (d) ATP synthase (e) coenzyme AThe aerobic part of aerobic cellular respiration occurs during (a) glycolysis (b) the conversion of pyruvate to acetyl CoA (c) the citric acid cycle (d) electron transport (e) all the preceding are aerobic processes7TYUA net profit of only 2 ATPs can be produced anaerobically from the _____ of one molecule of glucose, compared with a maximum of 38 ATPs produced in _____. (a) fermentation; anaerobic respiration (b) aerobic respiration; fermentation (c) aerobic respiration; anaerobic respiration (d) dehydrogenation; decarboxylation (e) fermentation; aerobic respirationWhen deprived of oxygen, yeast cells obtain energy by fermentation, producing carbon dioxide, ATP, and (a) acetyl CoA (b) ethyl alcohol (c) lactate (d) pyruvate (e) citrateWhich of the following is a correct ranking of molecules with respect to their energy value in glycolysis (note: means greater than)? (a) two pyruvates one glucose (b) one glucose one fructose-1,6-bisphosphate (c) two glyceraldehyde-3-phosphates (G3P) one glucose (d) two pyruvates one fructose-1,6-bisphosphate (e) two pyruvates two glyceraldehyde-3-phosphates (G3P)11TYUCONNECT Explain why the proton gradient formed during chemiosmosis represents a state of low entropy. (You may wish to refer to the discussion of entropy in Chapter 7.)CONNECT How are the endergonic reactions of the first phase of glycolysis coupled to the hydrolysis of ATP, which is exergonic? How are the exergonic reactions of the second phase of glycolysis coupled to the endergonic synthesis of ATP and NADH?PREDICT Could the inner mitochondrial membrane carry out its functions in the coupling of electron transport and ATP synthesis if its lipid bilayer were readily permeable to hydrogen ions (protons)?15TYU16TYUEVOLUTION LINK The reactions of glycolysis are identical in all organismsprokaryotes, protists, fungi, plants, and animalsthat obtain energy from glucose catabolism. What does this universality suggest about the evolution of glycolysis?18TYUDescribe the physical properties of light and explain the relationship between a wavelength of light and its energy.1C2CDiagram the internal structure of a chloroplast and explain how its components interact and facilitate the process of photosynthesis.3LO1CWhat is the significance that the combined absorption spectra of chlorophylls a and b roughly match the action spectrum of photosynthesis? Would photosynthesis be more efficient if their individual absorption spectra coincided exactly?3CDescribe photosynthesis as a redox process.Distinguish between the light-dependent reactions and Carbon fixation reactions of photosynthesis.1CIn what ways do the carbon fixation reactions depend on the light-dependent reactions?Describe the flow of electrons through photosystems I and II in the noncyclic electron transport pathway and the products produced. Contrast this flow with cyclic electron transport.Explain how a proton (H+) gradient is established across the thylakoid membrane and how this gradient functions in ATP synthesis.1C2CPREDICT Can cyclic electron transport alone support photosynthesis? Explain your answerSummarize the three phases of the Calvin cycle and indicate the roles of ATP and NADPH in the process.9LO10LODescribe what happens in each of the three phases of the Calvin cycle.A decrease in entropy occurs during the CO2 uptake phase of the Calvin cycle, as freely moving CO2 molecules become fixed into a carbon skeleton. How can this occur without direct participation by NADPH and/or ATP?In what ways does photorespiration differ from aerobic cellular respiration?4C11LO1CState the importance of photosynthesis both in a plant and to other organisms.1C2CWhere is chlorophyll located in the chloroplast? (a) thylakoid membranes (b) stroma (c) matrix (d) thylakoid lumen (e) between the inner and outer membranesIn photolysis some of the energy captured by chlorophyll is used to split (a) CO2 (b) ATP (c) NADPH (d) H2O (e) both b and c3TYUIn ________, electrons that have been energized by light contribute their energy to add phosphate to ADP, producing ATP. (a) crassulacean acid metabolism (b) the Calvin cycle (c) photorespiration (d) C4 pathways (e) photophosphorylationThe Calvin cycle begins when CO2 reacts with (a) phosphoenolpyruvate (b) glyceraldehyde-3-phosphate (c) ribulose bisphosphate (d) oxaloacetate (e) phosphoglycerateThe enzyme directly responsible for almost all carbon fixation on Earth is (a) rubisco (b) PEP carboxylase (c) ATP synthase (d) phosphofructokinase (e) maltase7TYUAn organism characterized as a photoautotroph obtains energy from _____ and carbon from _______. (a) light; organic molecules (b) light; CO2 (c) organic molecules; organic molecules (d) organic molecules; CO2 (e) O2; CO2VISUALIZE Draw a simple sketch illustrating a thylakoid membrane that is actively involved in chemiosmosis and label the two compartments it separates. Add the ATP synthase complex, indicate the proton gradient, and specify in which compartment ATP is synthesized.10TYU11TYU12TYUCONNECT High-energy electrons from glucose are used to drive ATP synthesis in aerobic respiration. How did these electrons become so energetic?PREDICT What would life be like for photoautotrophs if there were no chemoheterotrophs? for chemoheterotrophs if there were no photoautotrophs?EVOLUTION LINK Propose an explanation for bacteria, chloroplasts, and mitochondria all having ATP synthase complexes.INTERPRET DATA The figure depicts the absorption spectrum of a plant pigment. What colors or wavelengths does it absorb? What is the color of this pigment?SCIENCE, TECHNOLOGY, AND SOAETY What strategies may be employed in the future to increase the world food supply? Base your answer on your knowledge of photosynthesis and related processes.Discuss the significance of chromosomes in terms of their information content.Explain how DNA is packed into chromosomes in eukaryotic cells.What are the informational units on chromosomes called? Of what do these informational units consist?How is the large discrepancy between DNA length and nucleus size addressed in eukaryotic cells?Identify the stages in the eukaryotic cell cycle and describe their principal events.Describe the structure of a duplicated chromosome, including the sister chromatids, centromeres, and kinetochores.5LO1CWhat are the stages of mitosis, and what happens in each stage?6LOWhat are cell-cycle checkpoints?2C7LODistinguish between haploid and diploid cells, and define homologous chromosomes.9LO10.2 What are the stages of mitosis, and what happens in each stage?1C2CCan haploid cells divide by mitosis? by meiosis?11LO1C2CA nucleosome consists of (a) DNA and scaffolding proteins (b) scaffolding proteins and histones (c) DNA and histones (d) DNA, histones, and scaffolding proteins (e) histones onlyTest Your Understanding 2. At which of the following stages do human skin cell nuclei have the same DNA content? (a) early mitotic prophase and late mitotic telophase (b) G1 and G2 (c) G1 and early mitotic prophase (d) G1 and late mitotic telophase (e) G2 and late mitotic telophaseIn a cell at __________, each chromosome consists of a pair of attached chromatids, (a) mitotic prophase (b) meiotic prophase II (c) meiotic prophase I (d) meiotic anaphase I (e) all the precedingThe molecular tether that links sister chromatids of a duplicated chromosome to each other is (a) condensin (b) actin (c) myosin (d) cohesin (e) actomyosinIn an animal cell at mitotic metaphase, you would expect to find (a) two pairs of centrioles located on the metaphase plate (b) a pair of centrioles inside the nucleus (c) a pair of centrioles within each microtubule-organizing center (d) a centriole within each centromere (e) no centriolesA diploid nucleus at early mitotic prophase has __________ set(s) of chromosomes; a diploid nucleus at mitotic telophase has __________ set(s) of chromosomes. (a) 1; 1 (b) 1; 2 (c) 2; 2 (d) 2; 1 (e) not enough information has been givenYou would expect to find a synaptonemal complex in a cell at (a) mitotic prophase (b) meiotic prophase I (c) meiotic prophase II (d) meiotic anaphase I (e) meiotic anaphase IIA chiasma links a pair of (a) homologous chromosomes at prophase II (b) homologous chromosomes at late prophase I (c) sister chromatids at metaphase II (d) sister chromatids at mitotic metaphase (e) sister chromatids at metaphase IVISUALIZE Sketch a mitotic prophase chromosome and label sister chromatids, sister centromeres, and sister kinetochores.CONNECT Does the DNA content of the cell change from the beginning of interphase to the end of interphase? Does the number of chromosomes change? Explain.Fill out the following table for a cell with 5 chromosomes undergoing mitosis. Is this cell haploid or diploid? How do you know?Fill out the following table for a diploid cell with 14 chromosomes undergoing meiosis.In questions 13 and 14, decide whether each is an example of sexual or asexual reproduction, and state why. 13. A diploid queen honeybee produces haploid eggs by meiosis. Some of these eggs are never fertilized and develop into haploid male honeybees (drones).14TYUEVOLUTION link How does mitosis provide evidence for relationships among eukaryotes as diverse as mammals and seaweeds?16TYUDefine the terms phenotype, genotype, locus, allele, dominant allele, recessive allele, homozygous, and heterozygous.Describe Mendels principles of segregation and independent assortment.Distinguish among monohybrid, dihybrid, and test crosses.Explain Mendels principles of segregation and independent assortment, given what scientists now know about genes and chromosomes.What is the maximum number of different alleles for a particular locus that can be present in a single diploid individual?Can Mendels principle of segregation be illustrated by a cross between two homozygous dominant individuals? two homozygous recessive individuals?3CPREDICT Use the rules of probability to answer the following question: in a cross between homozygous pea plants with yellow, round seeds (YYRR) and homozygous pea plants with green, wrinkled seeds (yyrr), what is the probability of an F2 plant having yellow, round seeds?In answering the previous question, did you use the product rule, the sum rule, or both?Define linkage and relate it to specific events in meiosis.Show how data from a two-point test cross can be used to distinguish between independent assortment and linkage.Discuss the genetic determination of sex and the inheritance of X-linked genes in mammals.What ratio of genotypes to phenotypes is observed in a two-point test cross if genes are unlinked?2CCONNECT Two loci exhibit 5% recombination between them. How many map units apart are they?Which chromosome determines the male sex in humans and other mammals?5CExplain some of the ways genes may interact to affect the phenotype and discuss how a single gene can affect many features of the organism simultaneously.Distinguish among incomplete dominance, codominance, multiple alleles, epistasis, and polygenic inheritance.11LO1CWhat is the difference between multiple alleles and polygenic inheritance?3C4COne of the autosomal loci controlling eye color in fruit flies has two alleles: one for brown eyes and the other for red eyes. Fruit flies from a true-breeding line with brown eyes were crossed with flies from a true-breeding line with red eyes. The F1 flies had red eyes. What conclusion can be drawn from this experiment? (a) these alleles underwent independent assortment (b) these alleles underwent segregation (c) these genes are X-linked (d) the allele for red eyes is dominant to the allele for brown eyes (e) all the preceding are trueThe F1 flies described in question 1 were mated with brown-eyed flies from a true-breeding line. What phenotypes would you expect the offspring to have? (a) all with red eyes (b) all with brown eyes (c) half with red eyes and half with brown eyes (d) red-eyed females and brown-eyed males (e) brown-eyed females and red-eyed malesThe type of cross described in question 2 is (a) an F2 cross (b) a dihybrid cross (c) a test cross (d) a two-point test cross (e) none of the precedingIndividuals of genotype AaBb were crossed with aabb individuals. Approximately equal numbers of the following classes of offspring were produced: AaBb, Aabb, aaBb, and aabb. These results illustrate Mendels principle(s) of (a) linkage (b) independent assortment (c) segregation (d) a and c (e) b and cAssume that the ratio of females to males is 1:1. A couple already has two daughters and no sons. If they plan to have a total of six children, what is the probability that they will have four more girls? (a) (b) (c) 116 (d) 132 (e) 164Redgreen color blindness is an X-linked recessive disorder in humans. Your friend is the daughter of a color-blind father. Her mother had normal color vision, but her maternal grandfather was color-blind. What is the probability that your friend is color-blind? (a) 1 (b) (c) (d) (e) 0When two long-winged flies were mated, the offspring included 77 with long wings and 24 with short wings. Is the short-winged condition dominant or recessive? What are the genotypes of the parents?The long hair of Persian cats is recessive to the short hair of Siamese cats, but the black coat color of Persians is dominant to the brown-and-tan coat color of Siamese. Make up appropriate symbols for the alleles of these two unlinked loci. If a pure black, long-haired Persian is mated to a pure brown-and-tan, short-haired Siamese, what will be the appearance of the F1 offspring? If two of these F1 cats are mated, what is the chance that a long-haired, brown-and-tan cat will be produced in the F2 generation? (Use the shortcut probability method to obtain your answer; then check it with a Punnett square.)Mr. and Mrs. Smith are concerned because their own blood types are A and B, respectively, but their new son, Richard, is blood type O. Could Richard be the child of these parents?A walnut comb rooster is mated to three hens. Hen A, which has a walnut comb, has offspring in the ratio of 3 walnut to 1 rose. Hen B, which has a pea comb, has offspring in the ratio of 3 walnut to 3 pea to 1 rose to 1 single. Hen C, which has a walnut comb, has only walnut comb offspring. What are the genotypes of the rooster and the three hens?Individuals of genotype AaBb were mated to individuals of genotype aabb. One thousand offspring were counted, with the following results: 474 Aabb, 480 aaBb, 20 AaBb, and 26 aabb. What type of cross is it? Are these loci linked? What are the two parental classes and the two recombinant classes of offspring? What is the percentage of recombination between these two loci? How many map units apart are they?Genes A and B are 6 map units apart, and A and C are 4 map units apart. Which gene is in the middle if B and C are 10 map units apart? Which is in the middle if B and C are 2 map units apart?VISUALIZE Sketch a series of diagrams showing each of the following, making sure to end each series with haploid cells: (a)How a pair of alleles for a single locus segregate in meiosis (b)How the alleles of two unlinked loci assort independently in meiosis (c)How the alleles of two linked loci undergo genetic recombinationCan you always ascertain an organisms genotype for a particular locus if you know its phenotype? Conversely, if you are given an organisms genotype for a locus, can you always reliably predict its phenotype? Explain.CONNECT Compare the mechanisms of genetic recombination in linked and unlinked genes.EVOLUTION LINK Darwins theory of evolution by natural selection is based on four observations about the natural world. One of them is that each individual has a combination of traits that makes it uniquely different. Darwin recognized that much of this variation among individuals must be inherited, but he did not know about Mendels mechanism of inheritance. Based on what you have learned in this chapter, briefly explain the variation among individuals that Darwin observed.INTERPRET DATA Using the graph in Figure 11-20, determine how many offspring were involved in the hypothetical cross studying skin color. What percentage had the lightest skin possible? the darkest skin possible? Figure 11-20 Polygenic inheritance in human s pigmentation This simplified example assumes that skin pigmentation in humans is governed by alleles of three unlinked loci. The alleles producing dark skin (A, B, and C) are represented by capital letters, but they are not dominant. Instead, their effects are additive. The number of dark dots, each signifying an allele producing dark skin, is counted to determine the phenotype. A wide range of phenotypes is possible when individuals of intermediate phenotype mate and have offspring (AaBbCc AaBbCc). The expected distribution of phenotypes is consistent with the superimposed normal distribution curve.Summarize the evidence that accumulated during the 1940s and early 1950s demonstrating that DNA is the genetic material.2LO1C2CExplain how nucleotide subunits link to form a single DNA strand.Describe how the two strands of DNA are oriented with respect to each other.5LO1C2C3CCite evidence from Meselson and Stahls experiment that enabled scientists to differentiate between semiconservative replication of DNA and alternative models.7LOExplain the complexities of DNA replication that make the process (a) bidirectional and (b) continuous in one strand and discontinuous in the other.Discuss how enzymes proofread and repair errors in DNA.10LOHow did the ability to distinguish old and newly synthesized DNA strands enable Meselson and Stahl to verify that DNA replication is semiconservative?What feature of DNA structure causes DNA replication to be continuous for one strand but discontinuous for the other?What is the reason that eukaryotic cells require telomerase, but bacterial cells do not?When Griffith injected mice with a combination of live rough-strain and heat-killed smooth-strain pneumococci, he discovered that (a) the mice were unharmed (b) the dead mice contained living rough-strain bacteria (c) the dead mice contained living smooth-strain bacteria (d) DNA had been transferred from the smooth-strain bacteria to the mice (e) DNA had been transferred from the rough-strain bacteria to the smooth-strain bacteriaWhich of the following inspired Avery and his colleagues to perform the experiments demonstrating that the transforming factor in bacteria is DNA? (a) that A is equal to T and that G is equal to C (b) Watson and Cricks model of DNA structure (c) Meselson and Stahls studies on DNA replication in E. coli (d) Griffiths experiments on smooth and rough strains of pneumococci (e) Hershey and Chase's experiments on the reproduction of bacteriophagesIn the Hershey-Chase experiment with bacteriophages, (a) harmless bacterial cells permanently transformed into virulent cells (b) DNA was shown to be the transforming factor of earlier bacterial transformation experiments (c) the replication of DNA was conclusively shown to be semiconservative (d) viral DNA was shown to enter bacterial cells and cause the production of new viruses within the bacteria (e) viruses injected their proteins, not their DNA, into bacterial cellsThe two complementary strands of the DNA double helix are held to each other by (a) ionic bonds between deoxyribose molecules (b) ionic bonds between phosphate groups (c) covalent bonds between nucleotide bases (d) covalent bonds between deoxyribose molecules (e) hydrogen bonds between nucleotide basesIf a segment of DNA is 5 CATTAC 3, the complementary DNA strand is (a) 3 CATTAC 5 (b) 3 GTAATG 5 (c) 5 CATTAC 3 (d) 5 GTAATG 3 (e) 5 CATTAC 5Each DNA strand has a backbone that consists of alternating (a) purines and pyrimidines (b) nucleotide bases (c) hydrogen bonds and phosphodiester linkages (d) deoxyribose and phosphate (e) phosphate and phosphodiester linkagesThe experiments in which Meselson and Stahl grew bacteria in heavy nitrogen conclusively demonstrated that DNA (a) is a double helix (b) replicates semiconservatively (c) consists of repeating nucleotide subunits (d) has complementary base pairing (e) is always synthesized in the 5 3 directionThe statement DNA replicates by a semiconservative mechanism means that (a) only one DNA strand is copied (b) first one DNA strand is copied and then the other strand is copied (c) the two strands of a double helix have identical base sequences (d) some portions of a single DNA strand are old and other portions are newly synthesized (e) each double helix consists of one old and one newly synthesized strandTopoisomerases (a) synthesize DNA (b) synthesize RNA primers (c) join Okazaki fragments (d) break and rejoin DNA to reduce torsional strain (e) prevent single DNA strands from joining to form a double helixA lagging strand forms by (a) joining primers (b) joining Okazaki fragments (c) joining leading strands (d) breaking up a leading strand (e) joining primers, Okazaki fragments, and leading strandsThe immediate source of energy for DNA replication is (a) the hydrolysis of nucleotides with three phosphate groups (b) the oxidation of NADPH (c) the hydrolysis of ATP (d) electron transport (e) the breaking of hydrogen bondsWhich of the following statements about eukaryotic chromosomes is false? (a) eukaryotic chromosomes have free ends (b) telomeres contain protein-coding genes (c) telomerase lengthens telomeric DNA (d) telomere shortening may contribute to cell aging (e) cells with active telomerase may undergo many cell divisions13TYU14TYU15TYUINTERPRET DATA In the Hershey-Chase experiment, the radioactive label 32P was present inside bacterial cells (i.e., in the pellet), whereas the radioactive label 35S was present outside bacterial cells (in the supernatant). What would the researchers have concluded had the reverse been true, that is, if the radioactive label 35S were inside the cells and the radioactive label 32P were outside the cells?EVOLUTION LINK How does DNA being the universal molecule of inheritance in all cells support evolutionary theory?Summarize the early evidence indicating that some genes specify the structure of proteins.Describe how Beadle and Tatums experiments connected certain genes to enzymes and proteins.1CHow did the work of each of the following scientistsGarrod, Beadle and Tatum, and Paulingcontribute to our understanding of the relationship between genes and proteins?Outline the flow of genetic information in cells, from DNA to RNA to polypeptide.Compare the structures of DNA and RNA.Explain why the genetic code is said to be redundant and virtually universal, and discuss how these features may reflect its evolutionary history.VISUALIZE Sketch a simple flow diagram that shows the relationships among the following: RNA, translation, DNA, transcription, and polypeptide.2CCompare the processes of transcription and DNA replication, identifying both similarities and differences.Compare bacterial and eukaryotic mRNAs, and explain the functional significance of their structural differences.In what ways are DNA polymerase and RNA polymerase similar? How do they differ?A certain template DNA strand has the following nucleotide sequence: 3TACTGCATAATGATT5 What would be the sequence of codons in the mRNA transcribed from this strand? What would be the nucleotide sequence of the complementary nontemplate DNA strand?What features do mature eukaryotic mRNA molecules have that bacterial mRNAs lack?Identify the features of tRNA that are important in decoding genetic information and converting it into protein language.Explain how ribosomes function in polypeptide synthesis.10LO11LOWhat are ribosomes made of? Do ribosomes carry information to specify the amino acid sequence of proteins?What happens in each stage of polypeptide synthesis: initiation, elongation, and termination?A certain mRNA strand has the following nucleotide sequence: 5AUGACGUAUAACUUU3 What is the anticodon for each codon? What is the amino acid sequence of the polypeptide? (Use Figure 13-5 to help answer this question.) Figure 13-5 The genetic code The genetic code specifies all possible combinations of the three bases that compose codons in mRNA. Of the 64 possible codons, 61 specify amino acids (see Figure 3-17 for an explanation of abbreviations). The codon AUG specifies the amino acid methionine and also signals the ribosome to initiate translation (start). Three codonsUAA, UGA, and UAGdo not specify amino acids; they terminate polypeptide synthesis (stop).Give examples of the different classes of mutations that affect the base sequence of DNA in protein encoding genes and explain the effects that each has on the polypeptide produced.What are the main types of mutations?2CBriefly discuss RNA interference.14LO15LO1C2C3C1TYUWhat is the correct order of information flow in bacterial and eukaryotic cells? (a) DNA mRNA protein (b) protein mRNA DNA (c) DNA protein mRNA (d) protein DNA mRNA (e) mRNA protein DNADuring transcription, how many RNA nucleotide bases would usually be encoded by a sequence of 99 DNA nucleotide bases? (a) 297 (b) 99 (c) 33 (d) 11 (e) answer is impossible to determine with the information givenThe genetic code is defined as a series of _______________ in _______________. (a) anticodons; tRNA (b) codons; DNA (c) anticodons; mRNA (d) codons; mRNA (e) codons and anticodons; rRNARNA differs from DNA in that the base _______________ is substituted for _______________. (a) adenine; uracil (b) uracil; thymine (c) guanine; uracil (d) cytosine; guanine (e) guanine; adenine6TYUWhich of the following is/are not found in a bacterial mRNA molecule? (a) stop codon (b) upstream leader sequences (c) downstream trailing sequences (d) start codon (e) promoter sequencesWhich of the following is/are typically removed from pre-mRNA during nuclear processing in eukaryotes? (a) upstream leader sequences (b) poly-A tail (c) introns (d) exons (e) all the preceding9TYUSuppose you mix the following components of protein synthesis in a test tube: amino acids from a rabbit, ribosomes from a dog, tRNAs from a mouse, mRNA from a chimpanzee, and necessary enzymes plus an energy source from a giraffe. If protein synthesis occurs, which animals protein will be made? (a) rabbit (b) dog (c) mouse (d) chimpanzee (e) giraffe11TYU12TYUCompare and contrast the formation of mRNA in bacterial and eukaryotic cells. How do the differences affect the way in which each type of mRNA is translated? Does one system have any obvious advantage in terms of energy cost? Which system offers greater opportunities for control of gene expression?Explain to a friend the experimental strategy that was used to decipher the genetic code.Biologists hypothesize that transposons eventually lose the ability to replicate and therefore remain embedded in DNA without moving around. Based on what you have learned in this chapter, suggest a possible reason for this loss.16TYU17TYU18TYUExplain why bacterial and eukaryotic cells have different mechanisms of gene regulation.1C2C2LODistinguish among inducible, repressible, and constitutive genes.Differentiate between positive and negative control, and show how both types of control operate in regulating the lac operon.5LO1CWhat structural features does the trp operon share with the lac operon?3C4C6LOGive examples of some of the ways eukaryotic DNA-binding proteins bind to DNA.8LO9LO10LO1C2C3C4C5CThe regulation of most bacterial genes occurs at the level of (a) transcription (b) translation (c) replication (d) posttranslation (e) postreplication2TYU3TYU4TYUInactive genes tend to be found in (a) highly condensed chromatin, known as euchromatin (b) decondensed chromatin, known as euchromatin (c) highly condensed chromatin, known as heterochromatin (d) decondensed chromatin, known as heterochromatin (e) chromatin that is not organized as nucleosomes6TYUWhich of the following is characteristic of genes and gene regulation in both bacteria and eukaryotes? (a) promoters (b) non-coding DNA within coding sequences (c) enhancers (d) operons (e) DNA located in a nucleusThrough alternative splicing, eukaryotes (a) reinforce gene inactivation (b) prevent transcription of heterochromatin (c) produce related but different proteins in different tissues (d) amplify genes to meet the requirement of high levels of a gene product (e) bind transcription factors to enhancers to activate transcriptionA mutation that inactivates the repressor gene of the lac operon results in (a) the continuous transcription of the structural genes (b) no transcription of the structural genes (c) the binding of the repressor to the operator (d) no production of RNA polymerase (e) no difference in the rate of transcriptionWhich of the following is an example of positive control? (a) transcription occurs when a repressor binds to an inducer (b) transcription cannot occur when a repressor binds to a corepressor (c) transcription is stimulated when an activator protein binds to DNA (d) a and b (e) a and c11TYUPREDICT Compare the types of bacterial genes associated with inducible operons, those associated with repressible operons, and those that are constitutive. Predict the category into which each of the following would most likely fit: (a) a gene that codes for RNA polymerase, (b) a gene that codes for an enzyme required to break down maltose, and (c) a gene that codes for an enzyme used in the synthesis of adenine.INTERPRET DATA Develop a simple hypothesis that would explain the behavior of each of the following types of mutants in E. coli. Mutant a: The map position of this mutation is in the trp operon. The mutant cells are constitutive; that is, they produce all the enzymes coded for by the trp operon, even if large amounts of tryptophan are present in the growth medium. Mutant b: The map position of this mutation is in the trp operon. The mutant cells do not produce any enzymes coded for by the trp operon under any conditions. Mutant c: The map position of this mutation is some distance from the trp operon. The mutant cells are constitutive; that is, they produce all the enzymes coded for by the trp operon, even if the growth medium contains large amounts of tryptophan.14TYU15TYUEVOLUTION LINK Suggest why evolution resulted in multiple levels of gene regulation in multicellular eukaryotes.17TYU1LOExplain how gel electrophoresis is used to characterize cloned DNA fragments.Describe how PCR is used to amplify a specific gene from total cellular DNA.Compare the possible differences between a eukaryotic protein-encoding gene cloned by PCR and the same gene cloned by reverse transcriptase PCR (RTPCR).1CDifferent forms of a protein are produced in the liver and in the brain by alternate splicing of its mRNA. How would a researcher clone the gene encoding that protein to study the form that was produced in the liver?What advantages does the PCR method have over gene cloning in bacterial vectors?Describe the features of a typical CRISPR locus in a bacterial cell.Explain the function of CRISPR in bacterial cells.Compare CRISPR-based endonucleases with restriction endonucleases.8LO1C2C3C