Deck 17: Manipulating the Genomes of Eukaryotes

Question 1

An Hfr strain has a plasmid inserted near the trp (tryptophan)locus.This Hfr strain is incubated with an F^- trp^- strain.We isolate a trp⁺ strain that can readily donate this trait to other trp^- strains.No other traits are transferred.What has happened?

A) an F⁺ trp plasmid has been generated
B) typical Hfr mating
C) transduction occurs
D) transformation occurs
E) no change in genotype has occurred

Answer 1

A

Question 2

Two bacteria grow together.One appears to donate DNA to the other.One of the bacteria contains a bacteriophage that is normally quiescent but occasionally forms a plaque.What sort of genetic exchange is most likely to be occurring?

A) transformation
B) conjugation
C) transduction
D) electroporation
E) transposition

Answer 2

C

Question 3

Certain protozoa engulf cyanobacteria (photosynthetic bacteria)and maintain a given number of the cyanobacteria even when they divide.The protozoa divide only after the cyanobacteria have doubled their number.The cyanobacteria excrete glucose that the protozoa use for energy.This is a good example of

A) parasitism by protozoa.
B) how protozoa consume particulate food.
C) establishment of an endosymbiotic relationship.
D) symbiosis between two microorganisms.
E) convergent evolution.

Answer 3

C

Question 4

Rhizobia are bacteria that live symbiotically in the roots of leguminous plants.It has been proposed that some enzymes in the bacteria were derived from the plant.What mechanism would most likely have been involved in this?

A) transduction
B) transformation
C) conjugation
D) transposition
E) protoplasting

Question 5

Which of the follow is not true of a bacterial chromosome?

A) is circular.
B) is covalently closed.
C) is double-stranded DNA.
D) contains mobile sequences.
E) is a left-handed helix.

Question 6

Which of the following is an infection in newborn infants when born to a mother with gonorrhea?

A) pneumonia
B) brain lesions
C) eye infection
D) heart disease
E) tendon inflammation

Question 7

When eukaryotic cells are stained with DNA-specific dyes and viewed under the light microscope,DNA molecules are revealed in

A) the nucleus only.
B) the mitochondrion only
C) the chloroplasts only.
D) all these places: nucleus,mitochondrion,and chloroplast.
E) the mitochondrion and chloroplast only.

Question 8

________ are small circular pieces of DNA frequently found in bacteria.

A) Transposons
B) Insertion sequences
C) Plasmids
D) Bacteriophage
E) Centromeres

Question 9

Which of the following is not true of human mtDNA?

A) it encodes all of its own proteins
B) it can all be traced back to females that lived in Africa 20,000 years ago
C) it encodes components of the electron transport chain
D) it encodes all of the rRNA for its own ribosomes
E) it has a higher mutation frequency than nuclear DNA

Question 10

A bacterium is found that is resistant to the antibiotic gentamicin.The bacterium was isolated in a hospital where patients were routinely given gentamicin for a variety of infections.What was the pressure that selected for this resistant population?

A) Presence of gentamicin in the environment.
B) High mutation rate for the bacterium.
C) Growth situation for the bacterium.
D) Patients not receiving antibiotic provided source of bacteria.
E) Tainted food.

Question 11

We spread 10⁹ bacteria on a plate with 25 µg streptomycin/mL media.Four colonies grow.These colonies contain bacteria that are

A) wild-type.
B) resistant to streptomycin.
C) resistant to all antibiotics.
D) able to grow in unusual circumstance.
E) infected with bacteriophage.

Question 12

Which technique is used to make a copy of the colonies on a petri plate? One plate can be analyzed by a destructive method,while the other is retained for future use.

A) penicillin selection
B) replica plating
C) bifurcated plating
D) liquid culture
E) capillary transfer

Question 13

We grow resistant (Str^r)cells to a concentration of 10⁹ and plate them on a medium with 25 µg/mL gentamicin.Six colonies grow.These cells should be

A) Str^r.
B) Gen^r.
C) Str^r Gen^r.
D) wild-type.
E) Str^r Gen^s.

Question 14

Bacteriophages proliferate in the host cell and then lyse the cell when they have perhaps 100 new phages.How many phages on average could be produced from a culture with 10⁹ bacteria?

A) 10⁹
B) 10¹⁰
C) 10¹¹
D) 10¹²
E) 10¹³

Question 15

What would happen if a transposon were to "jump" into the origin of the bacteria genome?

A) Transposon would be replicated like the genome.
B) Transposon would "jump" to another location.
C) Transposon would inactivate the origin,no DNA replication possible.
D) Transposon would express its genes constitutively.
E) None of the choices would occur.

Question 16

There are "promiscuous plasmids," plasmids that can be interchanged between very different bacteria.These often pick up transposons carrying antibiotic resistance.We are in a hospital that has an outbreak of a variety of bacteria carrying resistance to streptomycin,gentamicin,and penicillin.Which of these would not be helpful in determining how this was occurring?

A) Test all the resistant bacteria for a plasmid.
B) See if the same plasmid could be isolated from all resistant bacteria.
C) See if the plasmid isolated from the bacteria conferred resistance to a test bacterium.
D) With restriction mapping,see if the plasmid seemed to contain transposons known to carry resistance to these antibiotics.
E) Test whether the plasmids contained an origin of replication.

Question 17

Traits showing non-Mendelian inheritance are inherited from

A) the mother.
B) the father.
C) both parents.
D) Depending on species,inheritance could be from mother,father,or both parents.
E) both grandparents.

Question 18

We isolate nine different mutants unable to make histidine.They map in different locations and by genetic means we can show there are nine different genes in the pathway.How many enzymes can we anticipate finding in this pathway?

A) 1
B) 3
C) 6
D) 9
E) 12

Question 19

With traits showing maternal inheritance,such as leaf variegation in four o'clocks,reciprocal crosses usually

A) yield the same results.
B) yield different results.
C) yield results that can seldom be predicted.
D) eliminate the need for sexual reproduction.
E) show the trait to be X-linked.

Question 20

Which of the following is a bacterial disease that occurs among sexually active individuals?

A) gonorrhea
B) Haemophilus infections
C) pneumonia
D) pancreatitis
E) jaundice

Question 21

Molecular evidence suggests that DNA sequences may have been transferred between all of the following except

A) mtDNA and nuclear DNA
B) cpDNA and mtDNA
C) different cpDNA molecules
D) different species of bacteria
E) different species of mammals

Question 22

cpDNA-encoded proteins include

A) RNA polymerase only
B) RNA polymerase and translation factors only
C) RNA polymerase,translation factors,and ribosomal proteins
D) translation factors only
E) ribosomal proteins only

Question 23

Which type of DNA sequences might be studied to help reunite displaced children with their mothers?

A) mtDNA sequences
B) cpDNA sequences
C) Y-chromosome sequences
D) highly conserved nuclear sequences
E) tRNA sequences

Question 24

Semiautonomous as applied to mitochondria and chloroplasts means that they require gene products encoded in the cell's nuclear DNA.

Question 25

Which of the following has not been associated with aging in humans?

A) loss of mitochondria
B) 5kb and 7.4kb deletions in mtDNA of heart cells
C) loss of cytochrome oxidase c genes
D) mutations in mtDNA
E) shortening of mtDNA telomeres

Question 26

RNA editing can occur in mitochondrial transcripts and is the addition and/or deletion of uracils and/or cytosines,which results in codon changes from the original DNA.

Question 27

The universal code of DNA is the same for mtDNA as for chromosomal DNA.

Question 28

Which of the following relationships can be proven using mtDNA?

A) Boy and his mother's brother
B) Boy and his father's sister
C) Girl and her mother's father
D) Girl and her father's mother
E) Girl and her father's sister

Question 29

A homoplasmic cell carries

A) a mixture of organelle genomes.
B) only one type of organelle DNA.
C) only one mitochondrion.
D) two identical nuclei.
E) only one chloroplast.

Question 30

The codon UGA specifies

A) "start" in the "universal" genetic code.
B) the amino acid glycine in human mtDNA.
C) formyl-methionine in mtDNA.
D) both "stop" in the "universal" genetic code and the amino acid tryptophan in human mtDNA.
E) methionine in mtDNA genetic code.

Question 31

Inhibitors of bacterial translation,such as chloramphenicol and erythromycin,generally

A) are inhibitors of eukaryotic cytoplasmic protein synthesis.
B) are inhibitors of mitochondrial protein synthesis.
C) have no effect on mitochondrial protein synthesis.
D) are inhibitors of eukaryotic cytoplasmic protein synthesis and have no effect on mitochondrial protein synthesis.
E) are inhibitors of microtubules and cell division.

Question 32

Variegated four o'clock leaves have white patches among the green areas due to

A) an mtDNA mutation,which blocks electron transport.
B) a cpDNA mutation,which incapacitates proteins essential for photosynthesis.
C) a nuclear DNA mutation,which leads to mosaicism.
D) both cpDNA mutation which incapacitates proteins essential for photosynthesis and nuclear DNA mutation,which leads to mosaicism.
E) increased activity of transposable elements.

Question 33

A researcher hopes that a plant cell,after being shot with a gene gun,will

A) die.
B) incorporate foreign DNA into its nucleus.
C) mutate to a new genotype.
D) show uniparental inheritance.
E) incorporate foreign DNA into its mitochondria.

Question 34

Specialized transduction allows phages to pick up only adjacent DNA from the host chromosome during the transition from the lysogenic to the lytic cycle.

Question 35

Which of the following is not a symptom of myoclonic epilepsy and ragged red fibre disease (MERRF)?

A) heart and kidney problems
B) sudden fever
C) deafness
D) progressive memory loss
E) uncontrolled jerking

Question 36

Which of the following has been associated with Alzheimer's disease?

A) loss of mitochondria
B) 5kb and 7.4kb deletions in mtDNA of heart cells
C) mutations in cytochrome oxidase c genes in brain cells
D) mutations in mtDNA
E) shortening of mtDNA telomeres

Question 37

Which of the following statements is correct with respect to mitochondrial genes?

A) They are transmitted,largely intact,from parent to offspring.
B) Their inheritance shows Mendel's principle of segregation.
C) Their inheritance shows Mendel's principle of independent assortment.
D) Their inheritance follows a 3:1 ratio.
E) Their inheritance follows a 9:3:3:1 ratio.

Question 38

Which of the following is NOT accurate with regard to organelle genomes?

A) mtDNA and cpDNA are usually organized into nucleosomes by histones.
B) Mitochondrial translation is often inhibited by bacterial antibiotics (e.g. ,chloramphenicol).
C) Like bacteria,mitochondria use N-formyl methionine and tRNA^fMet in translation.
D) Organelle chromosomes are typically circular.
E) Organelle genomes are usually present in multiple copies.

Question 39

Human mitochondrial DNA contains tightly packed genes without introns.

Question 40

The molecules used in a chloroplast to carry out photosynthesis:

A) are all encoded by chloroplast DNA.
B) some are encoded by chloroplast DNA,others by nuclear DNA.
C) are all encoded by nuclear DNA.
D) some are encoded in nuclear DNA and some in mitochondrial DNA.
E) some are encoded in chloroplast DNA and some in mitochondrial DNA.

Question 41

Artificial transformation methods must be used on most bacteria to make them competent.

Question 42

An open reading frame is a long stretch of DNA that codes for amino acids and is uninterrupted by a stop codon.

Question 43

Small circular dsDNA molecules carrying non-essential genes,called plasmids,may exist as multiple copies in some bacteria.

Question 44

IS elements are plasmids that "insert" new phenotypes to bacteria.

Question 45

RNA editing occurs in the mitochondria of most organisms.

Question 46

Mating between bacteria can be disrupted using a kitchen blender.

Question 47

A transductant is a bacterium that has been the recipient of donor DNA from a bacteriophage.

Question 48

A plasmid that can integrate into the host bacterial genome is called an episome.

Question 49

Mutations in mtDNA are often caused by free-radical damage,which results from oxidative phosphorylation.

Question 50

Oxidative phosphorylation decreases with age.

Question 51

Mitochondrial DNA has an approximately 10-fold higher rate of mutation compared to nuclear DNA.

Question 52

Mitochondria in brain cells of patients with symptoms of Alzheimer's disease have unusually high energy metabolism.

Question 53

The lysogenic cycle of phage production results in bacterial cell lysis.

Question 54

An integrated copy of a temperate bacteriophage is called a prophage.

Question 55

Electroporation is the use of high voltage and high calcium salt to force foreign DNA into bacteria.

Question 56

Most bacteria are capable of natural transformation.

Question 57

The proportion of mutant mtDNAs and the tissue in which they reside influence phenotype.

Question 58

In uniparental inheritance,transmission is usually maternal.

Question 59

Mitochondria and chloroplasts are considered to be semiautonomous.

Question 60

Heteroplasmic cells lead to earlier appearance of mitochondrially inherited disease compared to homoplasmic cells.

Question 61

Explain how mitochondrial traits are inherited.

Question 62

Metagenomics is the analysis of genomic DNA from a community or habitat.Why would such studies be useful?

Question 63

Plasmids are small,circular pieces of DNA that some bacteria carry in addition to their own chromosome.Plasmids may include genes that benefit the bacterial host under certain conditions.Describe what some of these genes may be.

Question 64

Explain briefly the genetic technique known as recombineering.

Question 65

Identical twins arise from a single zygote.One twin has symptoms of MERFF but the other twin does not show the disorder.Explain how this might happen.

Question 66

Describe the difference between generalized and specialized transduction.

Question 67

The endosymbiont hypothesis posited by Lynn Margulis has now been elevated to being considered a theory.What molecular evidence strongly supports the hypothesis to the point that it is now accepted as a theory?

Question 68

Why might the brain cells show abnormally low energy metabolism in individuals with Alzheimer's disease?

Question 69

Explain why different Hfr cells can have F plasmids integrated at different sites.

Question 70

Explain the difference between the F^-,F⁺,Hfr,and F designations.

Question 71

Describe the difference between "selection" and "screen" with respect to mutant isolation methods.

Question 72

Since a mutation in an essential gene prevents a colony from growing,how would a bacteriologist study such a strain?

Question 73

Is the so-called "universal" genetic code truly universal? Why or why not?

Question 74

Why might a researcher attach a gene encoding a green fluorescent protein to a DNA sequence before transforming a cell's mtDNA?

Question 75

Describe five types of mutants that can be observed in bacteria.

Question 76

Mother 1 and Mother 2 both show a hypothetical mitochondria-related phenotype,and neither father is affected.Both families have four children.The children of family 1 are all affected,but only half of the children of family 2 show the phenotype.Interpret this result with respect to the genotype of Mother 1 and Mother 2.

Question 77

Describe how you would screen for Arg^- cells arising from a wild-type culture of E.coli.
To increase frequency of mutation,first expose wild-type culture to a mutagen.Then plate mutagenized cells onto minimal plates containing arginine.After colonies have grown up,replica plate onto minimal plates without arginine.Note position of cells that grow on first set of plates but not the second set.Those are the Arg^- mutants.