Deck 17: Transposable Genetics Elements

Question 1

Which enzyme catalyzes the excision and insertion events conducted by transposons?

A) Transformase
B) Transposase
C) Ligase
D) Helicase
E) Polymerase

Answer 1

B

Question 2

Eukaryotic DNA sequences that can move from one position to another are known as

A) DNA fingerprints.
B) plasmids.
C) transposons.
D) jumping chromosomes.
E) walking chromosomes.

Answer 2

C

Question 3

Which organism exhibits retrotransposition?

A) C. elegans
B) E. coli
C) S. aureus
D) E. coli and S. aureus
E) All of these

Answer 3

A

Question 4

When a bacterial cell is infected with a nonlytic bacteriophage with Tn5 on its chromosome,the frequency of Tn5 transposition is dramatically reduced if Tn5 is already maintained on the bacterial chromosome.Why?

A) Phage integration occurs via Tn5 homology disrupting the transposase.
B) Tn5 transposition is inhibited by phage gene products.
C) Tn5 on the bacterial chromosome expresses a repressor of transposition.
D) Transposase is not expressed from Tn5 elements integrated within the bacterial chromosome.
E) None of these

Question 5

Which category of transposons accomplishes transposition through a process that involves the insertion of copies of an element that were synthesized from the element's RNA?

A) Cut and paste transposons
B) Replicative transposons
C) Retrotransposons
D) Cut and paste transposons and Replicative transposons
E) All of these

Question 6

Which of the following enzymes is responsible for the synthesis of DNA from RNA which is then inserted into the new position in retrotransposition?

A) Transformase
B) Transposase
C) Reverse transcriptase
D) Ligase
E) Helicase

Question 7

Which of the following statements about IS elements is not correct?

A) IS elements are responsible for the formation of Hfr strains of E. coli.
B) IS elements are less than 2,500 nucleotide pairs in size and contain only genes involved with promoting or regulating transcription.
C) IS elements are demarcated by short, inverted terminal repeats which have no role in the transpositional process.
D) IS elements are capable of creating target site duplications.
E) All of these are correct.

Question 8

Cut and paste transposition can occur in which of the following organisms?

A) C. elegans
B) E. coli
C) S. aureus
D) E. coli and S. aureus
E) All of these

Question 9

Which type of transposon is not found in prokaryotes?

A) IS elements
B) Composite transposons
C) Tn3
D) Tac
E) All of these are found in prokaryotes.

Question 10

Short identical sequences at the ends of an IS sequence are known as

A) transposon telemorases.
B) inverted terminal repeats.
C) correlated terminal repeats.
D) transposable terminal repeats.
E) All of these f) None of these

Question 11

Replicative transposition can occur in which of the following organisms?

A) C. elegans
B) E. coli
C) S. aureus
D) E. coli and S. aureus
E) All of these

Question 12

When IS elements insert into chromosomes or plasmids,they create a duplication of part of the DNA sequence at the site of the insertion,with one copy of the duplication on each side of the element known as

A) inverted terminal repeats.
B) target site duplications.
C) target site deletions.
D) inverted terminal duplications.
E) inverted terminal deletions.

Question 13

Which transposable element found in bacteria is the simplest,containing only genes involved in transposition?

A) IS elements
B) Composite transposons
C) Tn3
D) Tac
E) None of these

Question 14

Which of the following describes the category of transposons in which transposition is accomplished by excising an element from its position in a chromosome and inserting it into another position?

A) Cut and paste transposons
B) Replicative transposons
C) Retrotransposons
D) Cut and paste transposons and replicative transposons
E) All of these

Question 15

What type of transposon is an IS element?

A) Cut and paste transposon
B) Replicative transposon
C) Retrovirus-like transposon
D) Retrotransposon
E) All of these

Question 16

What is formed when two IS elements insert near each other?

A) Replicative transposon
B) Composite transposon
C) Inverted terminal repeats
D) Inverted terminal duplications
E) Inverted terminal deletions

Question 17

Which type of transposon is a composite transposon?

A) Cut and paste transposon
B) Replicative transposon
C) Retrotransposon
D) Retrovirus-like transposon
E) All of these

Question 18

Which of the following is not true regarding replicative transposition?

A) A transposase encoded by the element mediates an interaction between the element and a potential insertion site.
B) The element is replicated and one copy of it is inserted at the new site while one copy remains at the original site.
C) There is a net gain of one copy of the element.
D) All of these are true.
E) All of these are false.

Question 19

Which of the following describes the category of transposons in which transposition is accomplished through a process that involves replication of the transposable element's DNA?

A) Cut and paste transposons
B) Replicative transposons
C) Retrotransposons
D) Cut and paste transposons and replicative transposons
E) All of these

Question 20

Which of the following composite transposons exhibits differences (non-identical nature)in its flanking IS elements?

A) Tn 10
B) Tn 5
C) Tn 3
D) Tn 2
E) Tn 1

Question 21

Mutations generated by transposons can be located from a large,heterogeneous mixture of DNA by the known sequence of the transposon.What is this called?

A) Transposon localization
B) Transposon tagging
C) Transposon linking
D) Transposon marking
E) Transposon identification

Question 22

Which of the following is true regarding cut and paste transposons in eukaryotes?

A) These elements have inverted repeats at their termini.
B) These elements create target site duplications when they insert into DNA molecules.
C) Some encode a transposase that catalyzes the movement of the element from one position to another.
D) All of these
E) None of these

Question 23

Ds elements are characterized by a peculiar piggybacking arrangement in which one Ds element is inserted into another,but in an inverted orientation.These are known as

A) aberrant Ds elements.
B) unusual Ds elements.
C) double Ds elements.
D) aberrant Ds elements and unusual Ds elements.
E) All of these

Question 24

Plasmids that can move transposons from one bacterial cell to another are known as

A) conjugative R plasmids.
B) F plasmids.
C) Col plasmids.
D) Tn3 elements.
E) All of these

Question 25

What is another name for Ac and Ds transposable elements,which emphasizes the effect on gene expression?

A) Controsons
B) Controlling elements
C) Cosmids
D) Controsons and controlling elements
E) All of these

Question 26

What is the hobo element found in Drosophila?

A) Ac/Ds element
B) Replicative transposon
C) Retrotransposon
D) Tn3
E) IS

Question 27

Which of the following is true regarding the Ac element in maize?
1)Ac elements consist of 4563 nucleotide pairs.
2)Ac elements are bounded by inverted repeats that are 11 nucleotide pairs long.
3)Each Ac element is flanked by direct repeats 8 nucleotide pairs long.

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these

Question 28

Which term is used to denote the syndrome produced from Drosophila crosses that gave rise to hybrids with an assortment of aberrant traits,including frequent mutation,chromosome breakage?

A) Hybrid dysgenesis
B) Hybrid displasia
C) Hybrid polymorphism
D) Hybrid dysgenesis and hybrid displasia
E) All of these

Question 29

In maize,the Ac factor is not associated with

A) structural identity between different Ac elements.
B) the activator of chromosomal breakage in regions containing aberrant Ds.
C) Cis-acting in its ability to transpose Ds.
D) inverted terminal and direct repeats.
E) None of these

Question 30

Which of the following is true regarding the Ds element in maize?
1)Ds elements are structurally heterogeneous
2)Some Ds elements appear to have been derived from Ac elements by the loss of internal sequences
3)They all possess the same inverted terminal repeats as Ac elements

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these

Question 31

Why do Drosophila,from a P male x M female cross,generate viable offspring?

A) P element transposase is repressed in germ cells, at the level of RNA splicing.
B) P element transposase is repressed in germ cells, at the level of transcription.
C) P element transposase is repressed in somatic cells, at the level of RNA splicing.
D) P element transposase is repressed in somatic cells, at the level of transcription.
E) P male x M female crosses do not generate viable offspring.

Question 32

Some mariner elements show a high degree of similarity between organisms that are separated by millions of years of evolutionary time.What is the current explanation for this?

A) Mariner is highly conserved.
B) Mariner was horizontally transferred by bacterium.
C) Mariner was horizontally transferred by virus.
D) Mariner elements in divergent species have arisen through inter-species breeding events.
E) None of these

Question 33

Which of the following pairs of DNA sequences could qualify as terminal repeats of IS elements? (read all sequences as 5' to 3')

A) AATTCCGTG and AATTCCGTG
B) TTCGTT and TTCGTT
C) TGTGGCTTT and TTTCGGTGT
D) TCTTGG and GGTTCT
E) TATATA and ATATAT

Question 34

Which part of the conjugative R plasmid contains the genes for antibiotic resistance?

A) RTF
B) R determinant
C) ORI
D) Promoter
E) Enhancer

Question 35

Ds elements that contain non-Ac DNA between their inverted terminal repeats are known as

A) aberrant Ds elements.
B) unusual Ds elements.
C) double Ds elements.
D) aberrant Ds elements and Unusual Ds elements.
E) All of these

Question 36

Which of the following crosses would result in the movement of P elements and subsequent hybrid dysgenesis?

A) P cytotype females x P cytotype males
B) M cytotype females x M cytotype males
C) P cytotype females x M cytotype males
D) M cytotype females x P cytotype males
E) Hybrid dysgenesis is not induced by cytotype.

Question 37

Which of the following are encoded by the genes in Tn3 elements?

A) Transposase
B) Beta lacatamase
C) Resolvase
D) Transposase and Beta lacatamase
E) All of these

Question 38

Which of the following statements is true about Tn3 elements?

A) Tn3 form a cointegrate structure mediated by the tnpA gene product.
B) The cointegrate structure is required for replication.
C) Transposition is repressed by the dual nature of the tnpA gene product.
D) Tn3 elements are highly mobile.
E) All of these

Question 39

Which of the following has accelerated the spread of multiple drug resistance among bacterial infections?

A) Conjugative R plasmids
B) F plasmids
C) Col plasmids
D) Tn3 elements
E) All of these

Question 40

How are Tn3 elements classified?

A) Cut and paste transposon
B) Replicative transposon
C) Retrotransposon
D) Retrovirus-like transposon
E) All of these

Question 41

What is the function of HeT-A and TART transposons in flies?

A) Provide genetic variation by randomly hopping throughout the genome
B) To counterbalance the loss of chromosomal ends
C) To promote crossing-over between homologous chromosomes
D) To aid in the segregation of chromosomes
E) They have no known function.

Question 42

How does transposase act to catalyze transposition in IS elements?

Question 43

How does the transposition of a Tn3 element occur?

Question 44

How do IS elements of E.coli contribute to horizontal gene transfer?

Question 45

Which of the following statements is not true about L1 elements?

A) L1 is the only transposable element known to be active in humans.
B) L1 is unique to humans alone.
C) L1 elements are heterogeneous in size and maintained in single copy in the human genome.
D) L1 not is a retroposon.
E) None of these

Question 46

L1 transposition is known to cause disease when it is inserted into the gene for

A) Factor VII.
B) Huntingtin.
C) Dystrophin.
D) b-globin.
E) None of these

Question 47

If the P element of Drosophila contained no introns,would this affect the viability of P element carriers? If so,how?

Question 48

Which of the following is not involved in HIV infection?

A) Docks with target cell by binding the CD4 receptor via its gp120 protein
B) Polymerizes 1st DNA strand synthesis by the pol gene product
C) First strand synthesis is primed by snRNA.
D) DNA:RNA hybrid is degraded by RNase H.
E) The tRNA primer is prepackaged in the viral particle along with reverse transcriptase.

Question 49

Which of the following is a transposable element found in the human genome?

A) LINES
B) SINES
C) Retrovirus-like elements
D) All of these
E) None of these

Question 50

Explain how transposable elements are responsible for chromosomal breakage in the maize Ac/Ds system as shown by McClintock.

Question 51

In your search for mutants of "your favorite gene" (yfg)you identify a mutant which you believe to be a transposon insertion.At your disposal you have a point mutant of yfg.How can you distinguish this potential yfg transposon disruption from a non-transposon mutation?

Question 52

Which of the following elements exhibit homogeneous A:T sequences at one end?

A) Tn5
B) Ty elements
C) Mariner
D) P elements
E) Retroposons

Question 53

Which transposon(s)is responsible for leaving delta-sequences in the chromosome after transposition?

A) Tn5
B) Ty elements
C) Mariner
D) P elements
E) Retroposons

Question 54

If two transposons,in the same chromosome and in opposite orientation,pair and cross over,the segment between them will be

A) inverted.
B) deleted.
C) inactive.
D) unchanged.
E) None of these

Question 55

Retroviruses and retrovirus-like elements share all of the following genes except

A) Gag.
B) Pol.
C) Env.
D) Gag and Pol.
E) Pol and Env.

Question 56

Would you expect genes encoded by retrotransposons to contain introns? Why?