Mobile DNA Elements Flashcards

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1
Q

what is the mobilome?

A

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

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2
Q

what are the mobile genetic elements?

A

plasmids
bacteriophages
transposons/ IS elements

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3
Q

what are insertion sequences?

A

simplest form of MGE

encode for transposase gene and contain inverted repeats at both ends

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4
Q

how are insertion sequences transferred?

A

horizontal gene transfer

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5
Q

what are transposons?

A

MGEs larger than IS elements

possess inverted repeats and have proteins encoded

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6
Q

what proteins are encoded in transposons?

A

transposases, endonucleases, accessory genes

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7
Q

example of a bacterial DNA transposon?

A

carry antibiotic resistance genes to confer resistance

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8
Q

what is transposition?

A

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

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9
Q

what are retrotransposons?

A

recombination involving a transient RNA intermediate and retro transcription into cDNA

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10
Q

what happens when transposons transpose within regulatory regions?

A

change gene expression

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11
Q

what are the transposon families?

A

DNA transposons
Virus like retro transposons
poly A retro transposons

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12
Q

what is the structure of DNA transposons?

A

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

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13
Q

what are virus like retro transposons?

A

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

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14
Q

what are poly A transposons?

A

flanked by 5’ and 3’ UTR and a polyA

encodes for RNA binding protein and reverse transcriptase enzyme

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15
Q

what is the difference between transposons and retrotransposons?

A

transposons involved the cleavage and rejoining of DNA

retro transposons move to new DNA location using transient RNA intermediate

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16
Q

what does transposon Tn7 encode for?

A

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

17
Q

what do transposons Tn10R encode for?

A

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

18
Q

what does transposon TS10L do?

A

similar sequence to IS10R but does not encode a functional response

19
Q

how does Tn10 limit its copy number?

A

using antisense RNA to control the expression of the transposase gene

20
Q

what 2 groups can poly A retrotransposons be classified into?

A

autonomous LINE or non autonomous SINE

21
Q

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

A

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

22
Q

how does a LINE transposition occur?

A

reverse splicing

23
Q

how can retrotransposons be identified in eukaryotes?

A

they lack introns due to integration of cDNA from processed mRNA

24
Q

what can pseudogenes be caused by?

A

point mutations
homologous recombination
retrotransposition