Mobile DNA Elements

Question 1

what is the mobilome?

Answer 1

the fraction of genome containing all mobile genetic elements that can be transmitted through horizontal gene transfer

Question 2

what are the mobile genetic elements?

Answer 2

plasmids
bacteriophages
transposons/ IS elements

Question 3

what are insertion sequences?

Answer 3

simplest form of MGE

encode for transposase gene and contain inverted repeats at both ends

Question 4

how are insertion sequences transferred?

Answer 4

horizontal gene transfer

Question 5

what are transposons?

Answer 5

MGEs larger than IS elements

possess inverted repeats and have proteins encoded

Question 6

what proteins are encoded in transposons?

Answer 6

transposases, endonucleases, accessory genes

Question 7

example of a bacterial DNA transposon?

Answer 7

carry antibiotic resistance genes to confer resistance

Question 8

what is transposition?

Answer 8

the process of genetic recombination that mobilises genetic elements from one DNA site to another

Question 9

what are retrotransposons?

Answer 9

recombination involving a transient RNA intermediate and retro transcription into cDNA

Question 10

what happens when transposons transpose within regulatory regions?

Answer 10

change gene expression

Question 11

what are the transposon families?

Answer 11

DNA transposons
Virus like retro transposons
poly A retro transposons

Question 12

what is the structure of DNA transposons?

Answer 12

flanked by 2 inverted repeats (recombination sites) and a gene encoding a transposase remain as DNA throughout recombination

Question 13

what are virus like retro transposons?

Answer 13

flanked by 2 LTRs and region encoding for an integrase and reverse transcriptase

Question 14

what are poly A transposons?

Answer 14

flanked by 5’ and 3’ UTR and a polyA

encodes for RNA binding protein and reverse transcriptase enzyme

Question 15

what is the difference between transposons and retrotransposons?

Answer 15

transposons involved the cleavage and rejoining of DNA

retro transposons move to new DNA location using transient RNA intermediate

Question 16

what does transposon Tn7 encode for?

Answer 16

a protein TnsA with restriction endonuclease activity at ends of transposon
TsnB and TsnA excise the transposon from its target site

Question 17

what do transposons Tn10R encode for?

Answer 17

transposase that recognises the terminal inverted repeat sequence of IS10R, IS10L and Tn

Question 18

what does transposon TS10L do?

Answer 18

similar sequence to IS10R but does not encode a functional response

Question 19

how does Tn10 limit its copy number?

Answer 19

using antisense RNA to control the expression of the transposase gene

Question 20

what 2 groups can poly A retrotransposons be classified into?

Answer 20

autonomous LINE or non autonomous SINE

Question 21

what is the difference between autonomous and non autonomous poly a retrotransposons

Answer 21

autonomous encode for genes required to their own mobility and proteins
non autonomous cannot self promote

Question 22

how does a LINE transposition occur?

Answer 22

reverse splicing

Question 23

how can retrotransposons be identified in eukaryotes?

Answer 23

they lack introns due to integration of cDNA from processed mRNA

Question 24

what can pseudogenes be caused by?

Answer 24

point mutations
homologous recombination
retrotransposition