Mobile DNA: Transposons Flashcards

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1
Q

Who first identified transposons?

A

Barbara McClintock

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2
Q

How were transposons first identified?

A

In maize, transposons were found to be ‘controlling elements’ in the phenotypic expression of kernel color patterns

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3
Q

What are the three types of transposons?

A
  1. DNA only cut-and-paste element 2. LTR element 3. non-LTR element
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4
Q

What are the two functions of transposons?

A

Non-replicative, cut and paste transposition and replicative, nick and paste transposition

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5
Q

What is a retrotransposon?

A

A transposon which utilizes an RNA intermediate using reverse transcriptase

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6
Q

What is a non-LTR element?

A
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7
Q

True or false: transposons are found in all three domains of life.

A

True!

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8
Q

Where in the genome are transposons inserted?

A

Transposons can insert at random target sites in the genome

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9
Q

Can transposons move outside of the cell in which they are found?

A

No, most (but not all) transposons are confined to moving within the DNA of a single cell

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10
Q

What is a characteristic effect that transposition has on the DNA sequence it is inserted into?

A

Insertion results in a characteristic target site duplication

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11
Q

What is unique about autonomous transposons?

A

Autonomous transposons encode all the essential proteins required for their transposition

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12
Q

What is the co-dependent relationship between autonomous and non-autonomous transposons?

A

Non-autonomous transposons do not encode functional transposition proteins but instead rely on proteins encoded by other (autonomous) transposons

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13
Q

What are the metazoa?

A

The division of the animal kingdom that is multicellular animals with differentiated tissues

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14
Q

Transposable element-derived sequences are a
major component of…

A

metazoan genomes.

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15
Q

What is the genetic impact of transposon insertion?

A

Transposition disrupts gene function

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16
Q

How can transposons influence gene expression?

A

Some transposons carry promoters or other regulatory sequences which can influence nearby gene expression

17
Q

What can recombination between transposons lead to?

A

deletion of essential chromosomal regions (host organism death)

18
Q

Roughly how many human diseases are attributed to transposition?

A

More than 100 diseases.

19
Q

Explain the series of steps between L1 insertion and haemophilia.

A

Craig et al. p671-673

20
Q

What does LTR stand for?

A

Long terminal repeat

21
Q

What is a long terminal repeat? (LTR)

A
22
Q

What is the function of reverse transcriptase?

A

This enzyme synthesises DNA from an RNA template

23
Q

What is the simplest bacterial transposon?

A

Insertion sequences (IS elements)

24
Q

What is Tn10?

A

A compound transposon comprising two IS10 elements flanking a tetracycline-resistance gene

25
Q

What is a compound transposon?

A
26
Q

What mechanism does the bacteriophage Mu exemplify?

A

Replicative nick and paste transposition

27
Q

How many active non-LTR elements do human genomes usually contain?

A

100 active non-LTR elements

28
Q

What are the 4 steps of LTR retrotransposon transposition?

A
29
Q

How can LTR elements become extracellular?

A

By budding vesicles

30
Q

Provide an example of an extracellular LTR life cycle.

A

Yeast Ty1 - an LTR retrotransposon

31
Q

Provide an example of an intracellular LTR life cycle.

A

Murine leukaemia virus (MuLV) - a mammalian retrovirus

32
Q

Associate with the following acronyms the genetic structure of LTR elements:

GAG
PR
RT
RH
IN
ENV

A

GAG = nucleic acid binding
PR = protease
RT = reverse transcriptase
RH = RNase H
IN = integrase
ENV = envelope

33
Q

What are the two elements of Non-LTR retrotransposons?

A

LINE element and SINE element

34
Q

Why are so many LINE elements inactive?

A
35
Q

What is an example of ‘transposase domestication’?

A