Transposable Elements and Retroviruses

Question 1

Transposase

Answer 1

Enzyme activity involved with insertion of transposon

Question 2

Reverse transcriptase

Answer 2

Enzyme used to generate cDNA from RNA template

Question 3

Two main classes of transposons:

Answer 3

1) Retroelements (Class I) 2) DNA-Type elements (Class II)

Question 4

Transposon

Answer 4

DNA elements able to insert itself (or copy) into new location in the genome without having a relationship with the target sequence

Question 5

Transposons carried on P strains of D. melanogaster

Answer 5

P elements

Question 6

Cross for activation of P element insertion related infertility

Answer 6

P male x M female

Question 7

Transposon that encodes the enzyme(s) needed for transposition flanked by inverted terminal repeats

Answer 7

Insertion sequence (IS)

Question 8

Length of direct repeat

Answer 8

5-9 bp

Question 9

Transposon common mechanism

Answer 9

Staggered nicks in target DNA -> transposon joined to protruding ends -> gaps are filled

Question 10

Replicative transposition

Answer 10

Creates copy of transposon, donor unchanged

Question 11

Homologous recombination between transposon repeats can lead to ______ or _______

Answer 11

Precise, imprecise excision

Question 12

Nonreplicative transposition

Answer 12

Allows transposon to move from donor to recipient state, donor has a break at site of transposon

Question 13

Replicative transposition proceeds through ______

Answer 13

Cointegrate (fusion of donor and target replicons)

Question 14

Nonreplicative transposition proceeds through ______

Answer 14

Breakage and reunion

Question 15

Hybrid dysgenesis

Answer 15

Inability of certain strains of P. melanogaster to interbreed because hybrids are sterile

Question 16

P element produces a _______ of transposition

Answer 16

Repressor (inherited maternally in cytoplasm)

Question 17

Retrotransposons

Answer 17

Transposons that mobilize via an RNA form (DNA element transcribed to RNA, then reverse-transcribed to DNA, which is inserted into new site in the genome)

Question 18

Integrated provirus

Answer 18

Double-stranded DNA sequence

Question 19

How does retrorvirus generate provirus?

Answer 19

Reverse transcription of retroviral genome

Question 20

Retrovirus

Answer 20

Two copies of its genome of ssRNA

Question 21

Integrated provirus (sequence)?

Answer 21

Double-stranded DNA sequence

Question 22

Retrovirus (sequence)?

Answer 22

Two copies of its genome of ssRNA

Question 23

Retrovirus (3 genes)

Answer 23

Gag, pol, env (protein products then processed by proteases for polyproteins)

Question 24

Organization of proviral DNA in a chromosome is the same as a _________

Answer 24

Transposon

Question 25

Retroviral integrase enzyme

Answer 25

Inserts linear DNA directly into host chromosome

Question 26

Replication-defective virus

Answer 26

Virus that can’t perpetuate infective cycle because genes are absent, replaced by host DNA in case of transducing virus

Question 27

Helper virus

Answer 27

Helps replication-defective virus infect host

Question 28

Retroelements (3 classes):

Answer 28

1) LTR retrotransposons 2) non-LTR retrotransposons 3) SINES

Question 29

Alu elements (primate specific) structure

Answer 29

Left & right arms and two RNA polymerase III promoter

Question 30

Alu elements orientation

Answer 30

Either, forward and reverse can make pair and hairpin structures