Transposable Elements

Question 1

DNA sequences that can move within the genome

Answer 1

transposable genetic elements

Question 2

enzyme-driven process that moves transposable elements

Answer 2

transposition

Question 3

transposition is a – event that has a biological basis

Answer 3

mutational

Question 4

transposition typically create mutations by inserting themselves into wild-type alleles

Answer 4

insertional inactivation

Question 5

genetic element that was located at the site of chromosome breakage

Answer 5

dissociation (Ds) element

Question 6

chromosome breakage at Ds was activated by an unlinked genetic element,

Answer 6

activator (Ac) element

Question 7

the transposable element (central region) itself is flanked by

Answer 7

terminal inverted repeats

Question 8

the inserted transposable element is bracketed by

Answer 8

flanking direct repeats

Question 9

Flanking direct sequence is generated by – as part of the insertion event

Answer 9

DNA polymerase activity

Question 10

transpose through an RNA intermediate

Answer 10

retrotransposons (class I)

Question 11

transpose as DNA sequences

Answer 11

DNA transposons (class II)

Question 12

T/F: all DNA transposons carry the transposase gene that produces the transposase enzyme required for the movement of the transposon

Answer 12

true

Question 13

retrotransposons are composed of – but they are transcribed into RNA before transposition, and the RNA transcript is then copied back into DNA by reverse transcriptase

Answer 13

DNA

Question 14

the – is then inserted into a new location, where flanking direct repeats are formed

Answer 14

reverse-transcribed DNA

Question 15

T/F: retrotransposons are found in bacteria

Answer 15

false

Question 16

always generate new copies of themselves for transposition

Answer 16

retrotransposons

Question 17

T/F: DNA transposons found in bacterial, archaeal, and eukaryotic cells

Answer 17

true

Question 18

bacterial transposition = – transposition only

Answer 18

DNA

Question 19

transposon has terminal inverted repeats surrounding the transposase gene with no other genes present

Answer 19

simple transposons

Question 20

simple transposons in bacteria are identified as

Answer 20

insertional sequences

Question 21

contain two insertion sequences and one or more additional genes

Answer 21

composite transposons

Question 22

copy and paste = increase in number

Answer 22

replicative transposition

Question 23

cut and paste = same number

Answer 23

nonreplicative transposition

Question 24

retrotransposon transposition mechanism

Answer 24

replicative transposition

Question 25

DNA transposition mechanism

Answer 25

replicative or nonreplicative transposition

Question 26

simple DNA sequences that contain only the genetic info necessary for their own transposition

Answer 26

insertion sequences

Question 27

transposition of an IS element → formation

Answer 27

FDR

Question 28

transposition of IS element can produce mutation by inserting IS element into a

Answer 28

gene or regulatory sequence

Question 29

IS regions are potential sites of -- between bacterial chromosomes and plasmids forming Hfr chromosomes

Answer 29

recombination

Question 30

IS elements promote recombination that can lead to --

Answer 30

gene transfer

Question 31

T/F: all identified transposable elements in archaeal genomes are IS type

Answer 31

true

Question 32

example of composite transposon

Answer 32

Tn10

Question 33

bacterial composite transposons (Tn) are composed of two copies of an --, each flanked by its TIR sequences, and one or more additional genes

Answer 33

IS element

Question 34

T/F: Tn are longer than IS elements

Answer 34

true

Question 35

additional genes in Tn elements are variable and are contained in the -- that flanked by 2 IS elements

Answer 35

central region

Question 36

example of Noncomposite transposons

Answer 36

Tn3

Question 37

do not contain insertion sequences but do carry additional genes

Answer 37

noncomposite transposons

Question 38

noncomposite transposons transpose similar to --

Answer 38

composite transposons

Question 39

½ of human genome =

Answer 39

transposable elements

Question 40

Ac/Ds elements and P element =

Answer 40

DNA transposons

Question 41

more commonly eukaryotic transposable elements such as the human genome =

Answer 41

retrotransposons

Question 42

combination of sterility, high mutation rate, and a propensity chromosomal aberrations and nondisjunction

Answer 42

hybrid dysgenesis

Question 43

retrotransposons encode reverse transcriptase (--) to catalyze transposition

Answer 43

pol

Question 44

retrotransposons contain pol and gag but not --

Answer 44

env

Question 45

gene(s) carried by retrotransposons are flanked by -- that may be up to several 100s bp

Answer 45

long terminal repeats (LTRs)

Question 46

examples of retrotransposons

Answer 46

Ty elements in yeast copia elements of Drosophila LINE and SINE elements of humans

Question 47

All of the following are characteristics of insertion sequences elements except _______. - they are flanked by inverted repeats - they encode protein - there can be more than one copy of an IS element in a bacterial genome - a copy of the insertion sequence becomes integrated at a new location

Answer 47

a copy of the insertion sequence becomes integrated at a new location (The insertion sequence itself, not a copy, is excised from its original location and transferred to a new one.)

Question 48

IS elements contain the gene encoding --

Answer 48

transposase

Question 49

The role of transposase activity in IS element transposition includes _______.

Answer 49

cutting DNA at the target sequence | transposes makes staggered cuts at the site targeted for insertion

Question 50

Which of the following transposition events is most likely to result in a loss of function mutation? - Transposition of an IS element that contains a stop codon within the inverted repeat sequence - Insertion near the promoter region of a gene - Insertion of an IS element within the coding region of a gene

Answer 50

Insertion of an IS element within the coding region of a gene (Insertions of DNA elements within coding regions have the greatest potential for altering amino acid sequence and/or causing truncation of a polypeptide due to frameshift.)

Question 51

What sequences or structures within the DNA can be used to identify sites of transposition? - target site duplication and direct repeats - target site inversion and direct repeats - chromosome translocation and insertion of transposase gene - target site duplication and short tandem repeats - inverted loops

Answer 51

target site duplication and direct repeats

Question 52

What evidence suggests that copia elements of fruit flies and Ty elements of yeast are related to RNA-containing viruses? - They all contain gag genes. - They all contain pol genes. - They all have long terminal repeats at their ends. - They are present in the form of RNA sequences in cells. - They use reverse transcription for insertion into host chromosomes. - They all cause mutation by insertion. - They all contain env genes.

Answer 52

- They all contain gag genes. - They all contain pol genes. - They all have long terminal repeats at their ends. - They use reverse transcription for insertion into host chromosomes.

Question 53

Which of the following statements about an R factor is false? - Encodes multiple drug resistant genes. - Encodes genes that induce lysis of the bacterial cell. - Can be propagated horizontally through a bacterial population. - Encodes the genes required for conjugation.

Answer 53

- Encodes genes that induce lysis of the bacterial cell.