Test Bank For Concepts of Genetics 11th Edition By Klug, Cummings, Spencer & Palladino,

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Test Bank For Concepts of Genetics 11th Edition By Klug, Cummings, Spencer & Palladino,

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WITH ANSWERS

 

Concepts of Genetics 11th Edition By Klug, Cummings, Spencer & Palladino,

 

SAMPLE QUESTIONS

 

 

Chapter 1   Introduction to Genetics

 

1) What is the name of the company or institution that has access to the health, genealogical, and genetic information of approximately 270,000 residents of Iceland?

  1. A) National Institutes of Health
  2. B) deCODE
  3. C) Gattaca
  4. D) Biogen
  5. E) American Cancer Society

Answer:  B

Section:  Introduction

 

2) A biotechnology company, deCODE, is in the process of creating a database that contains ________.

  1. A) the gene sequences of all newborns in the United States beginning in 2006
  2. B) a compilation of all the known genes in humans throughout the free world
  3. C) health, genealogical, and genetic information of approximately 270,000 residents of Iceland
  4. D) a complete sequence of the human genome
  5. E) all the information available on the human genome project

Answer:  C

Section:  Introduction

 

3) Why did deCODE select Iceland for its ambitious research project?

  1. A) a relatively low degree of genetic diversity
  2. B) frequent and extensive mutational bursts
  3. C) high genetic diversity
  4. D) lack of genealogical information
  5. E) virtual absence of mutation

Answer:  A

Section:  Introduction

 

4) The genetic material DNA consists of basic subunits called ________.

  1. A) mitochondria
  2. B) lysosomes
  3. C) centrioles
  4. D) nucleotides
  5. E) None of the answers listed is correct.

Answer:  D

Section:  1.3

 

 

5) The immediate product of transcription is ________.

  1. A) a phospholipid
  2. B) an amino acid
  3. C) a protein
  4. D) a carbohydrate
  5. E) RNA

Answer:  E

Section:  1.3

6) In many species, there are two representatives of each chromosome. In such species, the characteristic number of chromosomes is called the ________ number. It is usually symbolized as ________.

  1. A) haploid; n
  2. B) haploid; 2n
  3. C) diploid; 2n
  4. D) diploid; n
  5. E) None of the answers listed is correct.

Answer:  C

Section:  1.2

 

7) Genetics is the study of ________.

  1. A) heredity and variation
  2. B) mutation and recession
  3. C) transcription and translation
  4. D) diploid and haploid
  5. E) replication and recombination

Answer:  A

Section:  1.2

 

8) Early in the twentieth century, Walter Sutton and Theodore Boveri noted that the behavior of chromosomes during meiosis is identical to the behavior of genes during gamete formation. They proposed that genes are carried on chromosomes, which led to the basis of the ________.

Answer:  Chromosome Theory of Inheritance

Section:  1.2

 

9) What is a mutation?

Answer:  A mutation is an inherited change in a gene.

Section:  1.2

 

10) What is a simple definition of an allele?

Answer:  An allele is a variant form of a gene.

Section:  1.2

 

 

11) Until the mid-1940s, many scientists considered proteins to be the likely candidates for the genetic material. Why?

Answer:  Proteins are the most abundant, universally distributed components in cells. Because of their great structural and functional diversity, they were considered likely candidates.

Section:  1.2

 

12) Name the individual who, while working with the garden pea in the mid-1850s, demonstrated quantitative patterns of heredity and developed a theory involving the behavior of hereditary factors.

Answer:  Gregor Mendel

Section:  1.2

 

13) What does the term genetics mean?

Answer:  Genetics is a subdiscipline of biology concerned with the study of heredity and variation at the molecular, cellular, developmental, organismal, and populational levels.

Section:  1.2

14) Name the substance that serves as the hereditary material in eukaryotes and prokaryotes.

Answer:  DNA or deoxyribonucleic acid

Section:  1.2

 

15) Name two individuals who provided the conceptual basis for our present understanding that genes are on chromosomes.

Answer:  Walter Sutton and Theodore Boveri

Section:  1.2

 

16) What term is used to describe the fact that different genes in an organism often provide differences in observable features?

Answer:  phenotype

Section:  1.2

 

17) A fundamental property of DNAs nitrogenous bases that is necessary for the double-stranded nature of its structure is ________.

Answer:  complementarity

Section:  1.3

 

18) Recombinant DNA technology is dependent on a particular class of enzymes, known as ________, that cut DNA at specific nucleotide sequences.

Answer:  restriction enzymes

Section:  1.4

 

19) Name the botanist who, in 1900, rediscovered the work of Gregor Mendel.

Answer:  Carl Correns

Section:  1.2

 

 

20) Genetics is commonly seen as being grouped into several general areas: transmission, molecular, and population/evolution. Which biological processes are studied in transmission genetics?

Answer:  Mendelian inheritance (segregation and independent assortment), modification of Mendelian patterns, and pedigree analysis

Section:  Introduction and Summary Points

 

21) Who owns transgenic organisms?

Answer:  Once produced, a patent can be obtained on a living organism, thereby offering exclusive use of the transgenic organism to the patent holder.

Section:  1.5

 

22) In 1996, a cloning experiment produced the sheep named Dolly. Contrary to the more traditional method of cloning by embryo splitting, Dolly was produced by which procedure?

Answer:  nuclear transfer

Section:  1.4

 

23) What term is applied to a variety of projects whereby genome sequences are deposited in databases for research purposes?

Answer:  genomics

Section:  1.6

24) The first draft of the human genome sequence was reported in 2001 by two groups, the publicly funded ________ and the private company ________.

Answer:  Human Genome Project; Celera Corporation

Section:  1.6

 

25) A number of genomes have been sequenced in recent years: Escherichia coli, Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and Mus musculus. What are the common names for these organisms?

Answer:  bacterium, yeast, roundworm, fruit fly, mouse

Section:  1.6, 1.7

 

26) What is meant by the term genome?

Answer:  The genome is all the DNA carried in an organism.

Section:  1.4

 

27) In nonviral systems, what is the nature of the hereditary substance?

Answer:  DNA (deoxyribonucleic acid) is a double-stranded polymer organized as a double helix.

Section:  1.3

 

28) What characterizes the content and function of a DNA microarray?

Answer:  A DNA microarray can carry thousands of genes that can be used to test for gene expression.

Section:  1.5

 

29) What is meant by the term gene?

Answer:  a unit of inheritance

Section:  Summary Points

 

30) Distinguish the functions of DNA and RNA in a eukaryote.

Answer:  DNA is responsible for the storage and replication of genetic information; RNA is involved in the expression of stored genetic information.

Section:  1.3

 

31) Name the bases in DNA and their pairing specificities.

Answer:  adenine:thymine, guanine:cytosine

Section:  1.3

 

32) What is meant by the term genetic code?

Answer:  The genetic code consists of a linear series of three adjacent nucleotides present in mRNA molecules.

Section:  1.3

 

33) Compare and contrast nonenzymatic and enzymatic proteins.

Answer:  Both are gene products, with their primary structure being a string of amino acids. Enzymes are required as catalysts for most biochemical reactions; nonenzymatic proteins include structural (collagen), protective (immunoglobins), and/or transport (hemoglobin) proteins.

Section:  1.3

34) List the two relatively complex processes in which genetic information is converted into functional products.

Answer:  transcription and translation

Section:  1.3

 

35) What term refers to the similarity between parents and offspring and what term refers to the lack of similarity between parents and offspring?

Answer:  Heredity refers to the similarity between parents and offspring and the similarity of members of the same species. Variation refers to the lack of similarity between parents and offspring and members of the same species.

Section:  1.1, 1.2

 

36) What is meant by the phrase the central dogma of genetics?

Answer:  functional and structural relationships among DNA, RNA, and protein

Section:  1.3

 

37) What is the composition of the genetic material?

Answer:  polymers of nucleotides making up DNA

Section:  1.3

 

38) What is meant by complementarity in terms of the structure of DNA?

Answer:  base pairing of A with T, and G with C

Section:  1.3

39) Reference is often made to adapter molecules when describing protein synthesis in that they allow amino acids to associate with nucleic acids. To what class of molecules does this term refer?

Answer:  tRNA

Section:  1.3

 

40) Given that DNA is the genetic material in prokaryotes and eukaryotes, what other general structures (macromolecules) and substances made by the cell are associated with the expression of that genetic material?

Answer:  RNA (messenger, ribosomal, transfer), ribosomes, enzymes, proteins

Section:  1.3

 

41) What is another term for a biological catalyst?

Answer:  enzyme

Section:  1.3

 

42) Research dealing with which human blood disorder was instrumental in linking the genotype to a specific phenotype, and what conclusion was reached?

Answer:  The work on sickle-cell anemia was instrumental in showing that a mutant gene produced a mutant protein molecule.

Section:  1.3

 

43) A commercially available chip that contains thousands of fields (genetic elements) can be used to assess an individuals genome. What is the name of this chip?

Answer:  microarray

Section:  1.5

44) Alternative forms of a gene are called ________.

Answer:  alleles

Section:  1.2

 

45) The various characteristics of organisms that result from their genetic makeup are collectively referred to as an organisms ________.

Answer:  phenotype

Section:  1.2

 

46) Organisms that are well understood from a scientific standpoint and are often used in basic biological research are often called ________.

Answer:  model organisms

Section:  1.7

 

47) Arabidopsis is a model organism for the study of ________.

Answer:  plants

Section:  1.7

 

 

48) Genetics is the study of heredity and variation.

Answer:  TRUE

Section:  1.2

 

49) Complementarity in a genetic sense refers to the polymerization of nucleotides in DNA.

Answer:  FALSE

Section:  1.3

 

50) Bioinformatics is a discipline involved in the development of hardware and software for processing, storing, and retrieving nucleotide and protein data.

Answer:  TRUE

Section:  1.6

 

Chapter 3   Mendelian Genetics

 

1) Which of the following groups of scientists were influential around the year 1900 in setting the stage for our present understanding of transmission genetics?

  1. A) Beadle, Tatum, Lederberg
  2. B) Watson, Crick, Wilkins, Franklin
  3. C) deVries, Correns, Tschermak, Sutton, Boveri
  4. D) Darwin, Mendel, Lamarck
  5. E) Hippocrates, Aristotle, Kolreuter

Answer:  C

Section:  3.5

 

2) Name the single individual whose work in the mid-1800s contributed to our understanding of the particulate nature of inheritance as well as the basic genetic transmission patterns. With what organism did this person work?

  1. A) Gregor Mendel; Pisum sativum
  2. B) George Beadle; Neurospora
  3. C) Thomas Hunt Morgan; Drosophila
  4. D) Calvin Bridges; Drosophila
  5. E) Boris Ephrussi; Ephestia

Answer:  A

Section:  Introduction

 

3) A recessive allele in tigers causes the white tiger. If two normally pigmented tigers are mated and produce a white offspring, what percentage of their remaining offspring would be expected to have normal pigmentation?

  1. A) 25%
  2. B) 50%
  3. C) about 66%
  4. D) 75%
  5. E) about 90%

Answer:  D

Section:  3.2

 

4) Polydactyly is expressed when an individual has extra fingers and/or toes. Assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having extra digits is caused by a dominant allele. The couple has a son with normal hands and feet, but the couples second child has extra digits. What is the probability that their next child will have polydactyly?

  1. A) 1/32
  2. B) 1/8
  3. C) 7/16
  4. D) 1/2
  5. E) 3/4

Answer:  D

Section:  3.2

5) Tightly curled or wooly hair is caused by a dominant gene in humans. If a heterozygous curly-haired person marries a person with straight hair, what percentage of their offspring would be expected to have straight hair?

  1. A) 25% curly
  2. B) 50% straight
  3. C) 75% curly
  4. D) 100% straight
  5. E) It is impossible to predict the outcome.

Answer:  B

Section:  3.2

 

6) Which types of phenotypic ratios are likely to occur in crosses when dealing with a single gene pair for which all the genotypic combinations are of equal viability?

  1. A) 9:3:3:1, 27:9:9:9:3:3:3:1
  2. B) 1:2:1, 3:1
  3. C) 1:4:6:4:1, 1:1:1:1
  4. D) 12:3:1, 9:7
  5. E) 2:3, 1:2

Answer:  B

Section:  3.2

 

7) Assume that a black guinea pig crossed with an albino guinea pig produced 5 black offspring. When the albino was crossed with a second black guinea pig, 4 black and 3 albino offspring were produced. What genetic explanation would apply to these data?

  1. A) albino = recessive; black = recessive
  2. B) albino = dominant; black = incompletely dominant
  3. C) albino and black = codominant
  4. D) albino = recessive; black = dominant
  5. E) None of the answers listed is correct.

Answer:  D

Section:  3.2

 

8) The fundamental Mendelian process that involves the separation of contrasting genetic elements at the same locus would be called ________.

  1. A) segregation
  2. B) independent assortment
  3. C) continuous variation
  4. D) discontinuous variation
  5. E) dominance or recessiveness

Answer:  A

Section:  3.2

 

 

9) The Chi-square test involves a statistical comparison between measured (observed) and predicted (expected) values. One generally determines degrees of freedom as ________.

  1. A) the number of categories being compared
  2. B) one less than the number of classes being compared
  3. C) one more than the number of classes being compared
  4. D) ten minus the sum of the two categories
  5. E) the sum of the two categories

Answer:  B

Section:  3.8

10) Assume that in a series of experiments, plants with round seeds were crossed with plants with wrinkled seeds and the following offspring were obtained: 220 round and 180 wrinkled.a) What is the most probable genotype of each parent?

(b) What genotypic and phenotypic ratios are expected?

(c) Based on the information provided in part (b), what are the expected (theoretical) numbers of progeny (400 total) of each phenotypic class?

Answer:

(a) assuming that round (W) is dominant to wrinkled (w): Ww ww

(b) 1:1

(c) 200

Section:  3.2

 

11) In peas, gray seed color is dominant to white. For the purposes of this question, assume that Mendel crossed plants with gray seeds with each other and the following progeny were produced: 320 gray and 80 white.

 

(a) What is the most probable genotype of each parent?

(b) What genotypic and phenotypic ratios are expected in the progeny of such a cross?

Answer:

(a) assuming the following symbols: G = gray and g = white, Gg Gg

(b) genotypic = 1:2:1, phenotypic = 3:1

Section:  3.2

 

 

12) Assume that you have a garden and some pea plants have solid leaves and others have striped leaves. You conduct a series of crosses [(a) through (e)] and obtain the results given in the table.

 

            Cross                        Progeny

                                                    solid              striped

 

(a)        solid striped                     55                     60

(b)        solid solid                        36                       0

(c)        striped striped                    0                     65

(d)       solid solid                        92                     30

(e)        solid striped                     44                       0

 

Define gene symbols and give the possible genotypes of the parents of each cross.

Answer:

(a) From cross (d), assume that solid (S) is dominant to striped (s): Ss ss.

(b) SS SS or SS Ss

(c) ss ss

(d) Ss Ss

(e) SS ss

Section:  3.2

 

13) The phenotype of vestigial (short) wings (vg) in Drosophila melanogaster is caused by a recessive mutant gene that independently assorts with a recessive gene for hairy (h) body. Assume that a cross is made between a fly with normal wings and a hairy body and a fly with vestigial wings and normal body hair. The wild-type F1 flies were crossed among each other to produce 1024 offspring. Which phenotypes would you expect among the 1024 offspring, and how many of each phenotype would you expect?

Answer:  Phenotypes: wild, vestigial, hairy, vestigial hairy

Numbers expected: wild (576), vestigial (192), hairy (192), vestigial hairy (64)

Section:  3.3

14) Two organisms, AABBCCDDEE and aabbccddee, are mated to produce an F1 that is self-fertilized. If the capital letters represent dominant, independently assorting alleles:

 

(a) How many different genotypes will occur in the F2?

(b) What proportion of the F2 genotypes will be recessive for all five loci?

(c) Would you change your answers to (a) and/or (b) if the initial cross occurred between AAbbCCddee aaBBccDDEE parents?

(d) Would you change your answers to (a) and/or (b) if the initial cross occurred between AABBCCDDEE aabbccddEE parents?

Answer:

(a) 35 = 243

(b) 1/243

(c) no

(d) yes

Section:  3.4

15) How many different kinds of gametes can be produced by an individual with the genotype AABbCCddEeFf?

Answer:  23 = 8

Section:  3.4

 

16) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two parents with normal pigmentation have an albino child.

 

(a) What is the probability that their next child will be albino?

(b) What is the probability that their next child will be an albino girl?

(c) What is the probability that their next three children will be albino?

Answer:

(a) 1/4

(b) 1/4 1/2 = 1/8

(c) 1/4 1/4 1/4 = 1/64

Section:  3.2

 

17) Dentinogenesis imperfecta is a rare, autosomal, dominantly inherited disease of the teeth that occurs in about one in 8000 people (Witkop 1957). The teeth are somewhat brown in color, and the crowns wear down rapidly. Assume that a male with dentinogenesis imperfecta and no family history of the disease marries a woman with normal teeth. What is the probability that

 

(a) their first child will have dentinogenesis imperfecta?

(b) their first two children will have dentinogenesis imperfecta?

(c) their first child will be a girl with dentinogenesis imperfecta?

Answer:

(a) 1/2

(b) 1/2 1/2 = 1/4

(c) 1/2 1/2 = 1/4

Section:  3.2

 

18) A certain type of congenital deafness in humans is caused by a rare autosomal (not X-linked) dominant gene.

 

(a) In a mating involving a deaf man and a deaf woman (both heterozygous), would you expect all the children to be deaf? Explain your answer.

(b) In a mating involving a deaf man and a deaf woman (both heterozygous), could all the children have normal hearing? Explain your answer.

(c) Another form of deafness is caused by a rare autosomal recessive gene. In a mating involving a deaf man and a deaf woman, could some of the children have normal hearing? Explain your answer.

Answer:

(a) No. In a mating involving heterozygotes, three genotypic classes are expected in the offspring: fully dominant, fully recessive, and heterozygous.

(b) Assuming that the parents are heterozygotes (because the gene is rare), it is possible that all of the children could have normal hearing.

(c) Since the gene in question is recessive, both of the parents are homozygous and one would not expect normal hearing in the offspring.

Section:  3.2

 

 

19) Among dogs, short hair is dominant to long hair and dark coat color is dominant to white (albino) coat color. Assume that these two coat traits are caused by independently segregating gene pairs. For each of the crosses given below, write the most probable genotype (or genotypes if more than one answer is possible) for the parents. It is important that you select a realistic symbol set and define each symbol below.

 

Parental Phenotypes                               Phenotypes of Offspring

 

                                                         Short         Long         Short          Long

                                                          Dark         Dark       Albino       Albino

 

(a) dark, short dark, long                  26              24                0                0

(b) albino, short albino, short              0                0            102              33

(c) dark, short albino, short               16                0              16                0

(d) dark, short dark, short               175              67              61              21

 

Assume that for cross (d), you were interested in determining whether fur color follows a 3:1 ratio. Set up (but do not complete the calculations) a Chi-square test for these data [fur color in cross (d)].

Answer:  Let A = dark, a = albino and L = short, l = long

 

(a)        AALl AAll or AALl Aall

(b)        aaLl aaLl

(c)        AaLL aaLL or AaLl aaLL or AaLL aaLl

(d)       AaLl AaLl

 

x2 =  = (242 243)2 /243 + (82 81)2 /81

Section:  3.3, 3.8

20) Which phenotypic ratio is likely to occur in crosses of two completely dominant, independently segregating gene pairs when both parents are fully heterozygous?

Answer:  9:3:3:1

Section:  3.3

 

21) Provide simple definitions that distinguish segregation and independent assortment.

Answer:  Segregation is the separation of alleles during meiosis; independent assortment states that a member of one gene pair has an equal and independent opportunity of segregating with either member of another gene pair.

Section:  3.3

 

22) In what ways is sample size related to statistical testing?

Answer:  By increasing sample size, one increases the reliability of the statistical test and decreases the likelihood of erroneous conclusions from chance fluctuations in the data.

Section:  3.8

 

 

23) In a Chi-square analysis, what condition causes one to reject (fail to accept) the null hypothesis?

Answer:  usually when the probability value is less than 0.05

Section:  3.8

 

24) If one is testing a goodness of fit to a 9:3:3:1 ratio, how many degrees of freedom would be associated with the Chi-square analysis?

Answer:  number of classes minus 1 = 3

Section:  3.8

 

25) Assuming no crossing over between the gene in question and the centromere, when do alleles segregate during meiosis?

Answer:  meiosis I, when homologous chromosomes go to opposite poles

Section:  3.2

 

26) Assuming a typical monohybrid cross in which one allele is completely dominant to the other, what ratio is expected if the F1s are crossed?

Answer:  3:1

Section:  3.2

 

27) Under what conditions does one expect a 9:3:3:1 ratio?

Answer:  dihybrid cross (F2) with independently assorting, completely dominant genes

Section:  3.3

 

28) Under what conditions does one expect a 1:1:1:1 ratio?

Answer:  This occurs in a cross involving doubly heterozygous individuals crossed to fully recessive individuals. The genes involved assort independently.

Section:  3.3

 

29) What is the probability of flipping a penny and a nickel and obtaining one head and one tail?

Answer:  1/2 (apply the sum law)

Section:  3.7

30) How many kinds of gametes will be expected from an individual with the genotype PpCcTTRr?

Answer:  8

Section:  3.4

 

31) Assume that a Chi-square test was conducted to test the goodness of fit to a 9:3:3:1 ratio and a Chi-square value of 10.62 was obtained. Should the null hypothesis be accepted?

Answer:  no

Section:  3.8

 

 

32) Assume that a Chi-square test was conducted to test the goodness of fit to a 3:1 ratio and that a Chi-square value of 2.62 was obtained. Should the null hypothesis be accepted? How many degrees of freedom would be associated with this test of significance?

Answer:  yes; 1

Section:  3.8

 

33) Assume that a Chi-square test provided a probability value of 0.02. Should the null hypothesis be accepted?

Answer:  no

Section:  3.8

 

34) In studies of human genetics, usually a single individual brings the condition to the attention of a scientist or physician. When pedigrees are developed to illustrate transmission of the trait, what term does one use to refer to this individual?

Answer:  proband

Section:  3.9

 

35) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two parents with normal pigmentation have an albino child. What is the probability that their next child will be albino?

Answer:  1/4

Section:  3.2

 

36) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two parents with normal pigmentation have an albino child. What is the probability that their next child will be an albino girl?

Answer:  1/4 1/2 = 1/8

Section:  3.2

 

37) Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two parents with normal pigmentation have an albino child. What is the probability that their next three children will be albino?

Answer:  1/4 1/4 1/4 = 1/64

Section:  3.2

38) The autosomal (not X-linked) gene for brachydactyly, short fingers, is dominant to normal finger length. Assume that a female with brachydactyly in the heterozygous condition is married to a man with normal fingers. What is the probability that

 

(a) their first child will have brachydactyly?

(b) their first two children will have brachydactyly?

(c) their first child will be a brachydactylous girl?

Answer:

(a) 1/2

(b) 1/2 1/2 = 1/4

(c) 1/2 1/2 = 1/4

Section:  3.2

39) Tightly curled hair is caused by a dominant autosomal gene in humans. If a heterozygous curly-haired person marries a person with straight hair, what phenotypes (and in what proportions) are expected in the offspring?

Answer:  1/2 curly (because the curly-haired individual is most likely heterozygous); 1/2 straight hair

Section:  3.2

 

40) A certain type of congenital deafness in humans is caused by a rare autosomal dominant gene. In a mating involving a deaf man and a deaf woman (both heterozygous), would you expect all the children to be deaf? Explain your answer.

Answer:  No. In a mating involving heterozygotes, three genotypic classes are expected in the offspring: fully dominant, fully recessive, and heterozygous.

Section:  3.2

 

41) A certain type of congenital deafness in humans is caused by a rare autosomal dominant gene. In a mating involving a deaf man and a deaf woman, could all the children have normal hearing? Explain your answer.

Answer:  Assuming that the parents are heterozygotes (because the gene is rare), it is possible that all of the children could have normal hearing.

Section:  3.2

 

42) A certain type of congenital deafness in humans is caused by a rare autosomal recessive gene. In a mating involving a deaf man and a deaf woman, could some of the children have normal hearing? Explain your answer.

Answer:  Since the gene in question is recessive, both of the parents are homozygous and one would not expect normal hearing in the offspring.

Section:  3.2

 

43) For the purposes of this question, assume that being Rh+ is a consequence of D and that Rh- individuals are dd. The ability to taste phenylthiocarbamide (PTC) is determined by the gene symbolized T (tt are nontasters). A female whose mother was Rh- has the MN blood group, is Rh+ and a nontaster of PTC, and is married to a man who is MM, Rh-, and a nontaster. List the possible genotypes of the children. Assume that all the loci discussed in this problem are autosomal and independently assorting.

Answer:  MMDdtt, MMddtt, MNDdtt, MNddtt

Section:  3.4

44) What conditions are likely to apply if the progeny from the cross AaBb AaBb appear in the 9:3:3:1 ratio?

Answer:  complete dominance, independent assortment, no gene interaction

Section:  3.3

 

 

45) Assume that a cross is made between a heterozygous tall pea plant and a homozygous short pea plant. Fifty offspring are produced in the following frequency:

 

30 = tall

20 = short

 

(a) What frequency of tall and short plants is expected?

(b) To test the goodness of fit between the observed and expected values, provide the needed statement of the null hypothesis.

(c) Compute a Chi-square value associated with the appropriate test of significance.

(d) How many degrees of freedom are associated with this test of significance?

Answer:

(a) 1:1 (25 tall and 25 short)

(b) The deviations from a 1:1 ratio (25 tall and 25 short) are due to chance.

(c) x2 = 2

(d) 1

Section:  3.2, 3.8

 

46) According to Mendels model, because of ________, all possible combinations of gametes will be formed in equal frequency.

Answer:  independent assortment

Section:  Introduction

 

47) Assuming independent assortment, what proportion of the offspring of the cross AaBbCcDd AabbCCdd will have the aabbccdd genotype?

Answer:  zero

Section:  3.4

 

48) In a statistical sense, as the sample size increases, the average deviation from the expected fraction or ratio is expected to ________.

Answer:  decrease

Section:  3.8

 

49) In a Chi-square test, as the value of the x2 increases, the likelihood of rejecting the null hypothesis ________.

Answer:  increases

Section:  3.8

 

50) Mendels postulate of independent assortment is supported by a 1:1:1:1 testcross ratio.

Answer:  TRUE

Section:  3.3

 

51) Mendels Law of Segregation is supported by a 1:1 testcross ratio.

Answer:  TRUE

Section:  3.2

 

52) Mendels discoveries were well received and understood by his contemporaries.

Answer:  FALSE

Section:  3.5

 

53) The nonfunctional form of a gene is called a wild-type allele.

Answer:  FALSE

Section:  3.5

 

54) A gene can have a maximum of two alleles.

Answer:  FALSE

Section:  3.5

 

55) To test Mendels Law of Segregation, the experimenter needs a minimum of two contrasting forms of a gene.

Answer:  TRUE

Section:  3.2

 

56) A 1:1 phenotypic ratio is expected from a monohybrid testcross with complete dominance.

Answer:  TRUE

Section:  3.2

 

57) Assuming complete dominance, a 3:1 phenotypic ratio is expected from a monohybrid sib or self-cross.

Answer:  TRUE

Section:  3.2

 

58) A 9:3:3:1 phenotypic ratio is expected from a dihybrid testcross.

Answer:  FALSE

Section:  3.3

 

Chapter 11   DNA Replication and Recombination

 

1) Which of the following terms accurately describes the replication of DNA in vivo?

  1. A) conservative
  2. B) dispersive
  3. C) semidiscontinuous
  4. D) nonlinear
  5. E) nonreciprocal

Answer:  C

Section:  11.1

 

2) Which term(s) accurately reflect(s) the nature of replication of the chromosome in E. coli?

  1. A) bidirectional and fixed point of initiation
  2. B) unidirectional and reciprocal
  3. C) unidirectional and fixed point of initiation
  4. D) multirepliconic and telomeric
  5. E) bidirectional and multirepliconic

Answer:  A

Section:  11.2, 11.3, 11.4

 

3) DNA polymerase III adds nucleotides ________.

  1. A) to the 3 end of the RNA primer
  2. B) to the 5 end of the RNA primer
  3. C) in the place of the primer RNA after it is removed
  4. D) to both ends of the RNA primer
  5. E) to internal sites in the DNA template

Answer:  A

Section:  11.2

 

4) DNA polymerase I is thought to add nucleotides ________.

  1. A) to the 5 end of the primer
  2. B) to the 3 end of the primer
  3. C) in the place of the primer RNA after it is removed
  4. D) on single-stranded templates without need for an RNA primer
  5. E) in a 5 to 5 direction

Answer:  C

Section:  11.2, 11.3

 

5) Structures located at the ends of eukaryotic chromosomes are called ________.

  1. A) centromeres
  2. B) telomerases
  3. C) recessive mutations
  4. D) telomeres
  5. E) permissive mutations

Answer:  D

Section:  11.7

6) Which cluster of terms accurately reflects the nature of DNA replication in prokaryotes?

  1. A) fixed point of initiation, bidirectional, conservative
  2. B) fixed point of initiation, unidirectional, conservative
  3. C) random point of initiation, bidirectional, semiconservative
  4. D) fixed point of initiation, bidirectional, semiconservative
  5. E) random point of initiation, unidirectional, semiconservative

Answer:  D

Section:  11.2, 11.3, 11.4

 

7) The discontinuous aspect of replication of DNA in vivo is caused by ________.

  1. A) polymerase slippage
  2. B) trinucleotide repeats
  3. C) the 5 to 3 polarity restriction
  4. D) topoisomerases cutting the DNA in a random fashion
  5. E) sister-chromatid exchanges

Answer:  C

Section:  11.3, 11.4, 11.5

 

 

8) Assume that a culture of E. coli was grown for approximately 50 generations in 15N (provided in the medium in the ammonium ion), which is a heavy isotope of nitrogen (14N). You extract the DNA from the culture, and it has a density of 1.723 gm/cm3 (water = 1.00 gm/cm3). From the literature, you determine that DNA containing only the common form of nitrogen, 14N, has a density of 1.700 gm/cm3. Bacteria from the 15N culture were washed in buffer and transferred to 14N medium for one generation immediately after which the DNA was extracted and its density determined.

 

(a) What would be the expected density of the extracted DNA?

 

(b) After you heat the extracted DNA until it completely denatures (95oC for 15 minutes), what would you expect the density of the DNA in the denatured extract to be? For the purposes of this question, assume that DNA has the same density regardless of whether it is single- or double-stranded.

 

(c) Assuming that the molar percentage of adenine in the extracted DNA was 20%, what would be the expected molar percentages of the other nitrogenous bases in this DNA?

 

(d) Assume that a fraction of the extracted DNA was digested to completion with the enzyme snake venom diesterase. This enzyme cleaves between the phosphate and the 3 carbon. Present a simplified diagram that would illustrate the structure of the predominant resulting molecule.

Answer:

(a) approximately 1.712

(b) 1.723 and 1.700

(c) thymine = 20%, guanine = 30%, cytosine = 30%

(d)

 

 

Section:  11.1

 

 

9) Refer to the following diagram of a generalized tetranucleotide to answer questions (a) through (e).

 

 

(a) Is this a DNA or an RNA molecule? ________

 

(b) Place an X (in one of the circles in the diagram) at the 3 end of this tetranucleotide.

 

(c) Given that the DNA strand, which served as a template for the synthesis of this tetranucleotide, was composed of the bases 5-ACAG-3, fill in the parentheses (in the diagram) with the expected bases.

 

(d) Suppose that one of the precursors for this tetranucleotide was a 32P-labeled guanine nucleoside triphosphate (the innermost phosphate containing the radioactive phosphorus).Circle the radioactive phosphorus atom as it exists in the tetranucleotide.

 

(e) Given that spleen diesterase (breaks between the phosphate and the 5 carbon) digests the pictured tetranucleotide, which base(s) among the breakdown products would be expected to be attached to the 32P?

Answer:

(a) DNA

(b) place in bottom circle

(c) 3-TGTC-5

(d) phosphate on the 5 side of the guanine

(e) thymine closer to the 5 end

Section:  11.2, 11.3

 

10) Assume that you are microscopically examining mitotic metaphase cells of an organism with a 2n chromosome number of 4 (one pair metacentric and one pair telocentric). Assume also that the cell passed through one S phase labeling (innermost phosphate of dTTP radioactive) just prior to the period of observation. Assuming that the circle below represents a cell, draw its chromosomes and the autoradiographic pattern you would expect to see.

Answer:

 

Section:  11.1

 

11) The Meselson and Stahl experiment provided conclusive evidence for the semiconservative replication of DNA in E. coli. What pattern of bands would occur in a CsCl gradient for conservative replication?

Answer:  After one generation in the 14N, there would be two bands, one heavy and one light (no intermediate). After the second generation in the 14N, there would also be two bands, one heavy and one light (no intermediate).

Section:  11.1

12) Given that the nature of DNA replication in eukaryotes is not as well understood as in prokaryotes, (a) present a description of DNA (chromosome) replication as presently viewed in eukaryotes and (b) state the differences known to exist between prokaryotic and eukaryotic DNA replication.

Answer:

(a) Eukaryotic DNA is replicated in a manner very similar to that in E. coli: bidirectional, continuous on one strand and discontinuous on the other, and similar requirements for synthesis (four deoxyribonucleoside triphosphates, divalent cation, template, and primer).

 

(b) Okazaki fragments are about one-tenth the size of those in bacteria. Different portions of the chromosome (euchromatin, heterochromatin) replicate at different times. There are multiple replication origins in eukaryotic chromosomes.

Section:  11.6

13) Each of the following terms refers to the replication of chromosomes. Describe the role (relationship) of each in (to) chromosome replication.

 

(a) Okazaki fragment

(b) Lagging strand (c)Bidirectional

Answer:

(a) Okazaki fragment is a short single-stranded stretches of DNA on the lagging strand. See figures in the Klug/Cummings text.

 

(b) Lagging strand is the side of the replication fork where synthesis is discontinuous. See figures in the Klug/Cummings text.

 

(c) Bidirectional indicates that from the point of initiation, replication occurs in both directions along the DNA. See figures in the Klug/Cummings text.

Section:  11.3, 11.4

 

14) Assume that you were growing cells in culture and had determined the cell-cycle time to be 24 hours. You introduce 3H thymidine and prepare autoradiographs of metaphase chromosomes after 48 hours. Of the chromosomes that are labeled, you expect two classes: one class that had completed one S phase in the label, and a second class that had completed a cellular division and an additional S phase in the label. Draw the DNA (double-stranded) labeling pattern for each chromosome that you would expect to find in these two types of metaphase chromosomes. (Use a broken line {- -} for labeled single strands of DNA and a solid line for unlabeled single strands of DNA.)

 

(a) metaphase chromosome having replicated once in label

(b) metaphase chromosome having gone through two S phases in label

Answer:

(a)

 

(b)

 

 

Section:  11.1

 

15) Below is a diagram of DNA replication as currently believed to occur in E. coli. From specific points, arrows lead to numbers. Answer the questions relating to the locations specified by the numbers.

 

 

(1) Which end (5 or 3) of the molecule is here?

(2) Which enzyme is probably functioning here to deal with supercoils in the DNA?

(3) Which enzyme is probably functioning here to unwind the DNA?

(4) Which nucleic acid is probably depicted here?

(5) What are these short DNA fragments usually called?

(6) Which enzyme probably functions here to couple these two newly synthesized fragments of DNA?

(7) Is this strand the leading or lagging strand?

(8) Which end (5 or 3) of the molecule is here?

Answer:

(1)        5

(2)        gyrase

(3)        helicase

(4)        RNA

(5)        Okazaki fragments

(6)        ligase

(7)        lagging

(8)        5

Section:  11.2, 11.3, 11.4

 

 

16) Assume that you grew a culture of E. coli for many generations in medium containing 15N (from the ammonium ion), a heavy isotope of nitrogen. You extract DNA from a portion of the culture and determine its density to be 1.723 gm/cm3 (call this sample A). You then wash the remaining E. coli cells and grow them for one generation in 14N, extract the DNA from a portion of the culture, and determine its density to be 1.715 gm/cm3 (call this sample B). You let the culture grow for one more generation in 14N, and extract the DNA (call this sample C). Each sample of DNA (A, B, and C) is then heated to completely denature the double-stranded structures, cooled quickly (to keep the strands separate), and subjected to ultracentrifugation. Present the centrifugation profiles for heat-denatured DNA (samples A, B, and C) that you would expect. Use the graph below. (Note: Although not the case, assume that single-stranded DNA has the same density as double-stranded DNA.)

 

 

 

Answer:

 

 

Section:  11.1

 

17) Assume that you grew a culture of E. coli for many generations in medium containing 15N (from the ammonium ion), a heavy isotope of nitrogen. You extract DNA from a portion of the culture and determine its density to be 1.723 gm/cm3 (call this sample A). You then wash the remaining E. coli cells and grow them for one generation in 14N, and extract the DNA from a portion of the culture (call this sample B). You let the culture grow for one more generation in 14N, and extract the DNA (call this sample C). Each sample of DNA (A, B, and C) is then subjected to ultracentrifugation. Present the centrifugation profiles that you would expect under (a) semiconservative replication and (b) conservative replication. (Note: Assume that unlabeled [14N] DNA has a density of 1.700 gm/cm3.)

Answer:

 

Section:  11.1

 

18) List four enzymes known to be involved in the replication of DNA in bacteria.

Answer:  Appropriate answers would include any four of the following: DNA polymerase I, III, ligase, RNA primase, helicase, gyrase

Section:  11.2, 11.3, 11.4

 

19) Which structural circumstance in DNA sets up the requirement for its semidiscontinuous nature of replication?

Answer:  5 > 3 polarity restrictions of DNA synthesis and the antiparallel orientation of the DNA strands in DNA

Section:  11.2, 11.3, 11.4

 

20) As unwinding of the helix occurs during DNA replication, tension is created ahead of the replication fork. Describe the nature of this tension and state the manner in which this tension is resolved.

Answer:  supercoiling; DNA gyrase

Section:  11.2, 11.3, 11.4

 

21) The complex of proteins that is involved in the replication of DNA is called a(n) ________.

Answer:  replisome

Section:  11.2

 

 

22) Given that the origin of replication is fixed in E. coli, what signals the location of the origin?

Answer:  a region called oriC, which consists of about 250 base pairs characterized by repeating sequences of 9 and 13 bases (9mers and 13mers)

Section:  11.3

23) Which protein is responsible for the initial step in unwinding the DNA helix during replication of the bacterial chromosome?

Answer:  DnaA

Section:  11.3

 

24) During DNA replication, what is the function of RNA primase?

Answer:  RNA primase provides a free 3-OH upon which DNA polymerization depends.

Section:  11.3, 11.4

 

25) Compare the rate of DNA replication in prokaryotes and eukaryotes.

Answer:  Eukaryotic DNA polymerases synthesize DNA at a rate 25 times slower (about 2000 nucleotides per minute) than do prokaryotes.

Section:  11.6

 

26) What is the name of the replication unit in prokaryotes, and how does it differ in eukaryotes?

Answer:  replicon; one replicon in prokaryotes, multiple replicons in eukaryotes

Section:  11.1, 11.3, 11.6

 

27) Describe the DNA base sequence arrangement at the end of the Tetrahymena chromosome and the resolution of DNA replication at the end of a linear DNA strand.

Answer:  Telomeres terminate in a 5-TTGGGG-3 sequence, and telomerase is capable of adding repeats to the ends, thus allowing the completion of replication without leaving a gap and shortening the chromosome following each replication.

Section:  11.7

 

28) Describe a somewhat extraordinary finding related to the Tetrahymena telomerase enzyme.

Answer:  The enzyme contains a short piece of RNA that is essential for its catalytic activity.

Section:  11.7

 

29) What term is used to describe genetic exchange at equivalent positions along two chromosomes with substantial DNA sequence homology?

Answer:  general or homologous recombination

Section:  11.8

 

30) Describe the function of the RecA protein.

Answer:  The RecA protein promotes the exchange of reciprocal single-stranded DNA molecules by enhancing hydrogen bond formation during strand displacement.

Section:  11.8

 

 

31) What three possible models were suggested to originally describe the nature of DNA replication?

Answer:  conservative, semiconservative, dispersive

Section:  11.1

32) Given the diagram below, assume that a G1 chromosome (left) underwent one round of replication in 3H-thymidine and the metaphase chromosome (right) had both chromatids labeled. Which of the following replicative models (conservative, dispersive, semiconservative) could be eliminated by this observation?

 

 

Answer:  conservative

Section:  11.3

 

33) Meselson and Stahl determined that DNA replication in E coli is semiconservative. What additive did they initially supply to the medium in order to distinguish new from old DNA?

Answer:  15N

Section:  11.1

 

34) Briefly describe what is meant by the term autoradiography and identify a classic experiment that used autoradiography to determine the replicative nature of DNA in eukaryotes.

Answer:  Autoradiography is a technique that allows an isotope to be detected within a cell; the Taylor, Woods, and Hughes (1957) experiment used 3H-thymidine.

Section:  11.1

 

35) What primary ingredients, coupled with DNA polymerase I, are needed for the in vitro synthesis of DNA?

Answer:  dNTP, DNA template, primer DNA or RNA, Mg++ (appropriate buffering, temperature, and salt concentrations might be considered secondary ingredients)

Section:  11.2

 

36) DNA replication in vivo requires a primer with a free 3 end. What molecular species provides this 3 end, and how is it provided?

Answer:  The free 3 end is provided by an RNA primer; it is provided by the enzymatic activity of RNA primase.

Section:  11.2, 11.3

 

 

37) DNA replication occurs in the 5 to 3 direction; that is, new nucleoside triphosphates are added to the 3 end.

Answer:  TRUE

Section:  11.2, 11.3

 

38) DNA replicates conservatively, which means that one of the two daughter double helices is old and the other is new.

Answer:  FALSE

Section:  11.2

39) DNA strand replication begins with an RNA primer.

Answer:  TRUE

Section:  11.3, 11.4

 

40) In general, DNA replicates semiconservatively and bidirectionally.

Answer:  TRUE

Section:  11.1

 

41) In ligase-deficient strains of E. coli, DNA and chromosomal replication are unaltered because ligase is not involved in DNA replication.

Answer:  FALSE

Section:  11.5

 

42) During replication, primase adds a DNA primer to RNA.

Answer:  FALSE

Section:  11.2, 11.3, 11.4

 

43) An endonuclease is involved in removing bases sequentially from one end of DNA or the other.

Answer:  FALSE

Section:  11.2, 11.3, 11.4

 

44) In the Meselson and Stahl (1958) experiment, bean plants (Vicia faba) were radioactively labeled so that autoradiographs could be made of chromosomes.

Answer:  FALSE

Section:  11.1

 

45) A nucleosome is a structure associated with the nuclear membrane. It helps maintain a stable relationship between the extracellular matrix and the membrane itself.

Answer:  FALSE

Section:  11.6

 

46) A characteristic of aging cells is that their telomeres become shorter.

Answer:  TRUE

Section:  11.7

 

 

47) Telomerase is an RNA-containing enzyme that adds telomeric DNA sequences onto the ends of linear chromosomes.

Answer:  TRUE

Section:  11.7

 

48) Bacteria are dependent on telomerase to complete synthesis of their chromosome ends.

Answer:  FALSE

Section:  11.7

 

49) Chromatin assembly factors (CAFs) move along with the replication fork and assemble new nucleosomes.

Answer:  TRUE

Section:  11.6

50) G-quartets are G-rich single-stranded tails that loop back on themselves forming G-G double stranded sections. Such looping is involved in aligning chromosomes for homologous recombination.

Answer:  FALSE

Section:  11.8

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