Class Notes (1,100,000)
CA (620,000)
Western (60,000)
BIOL (7,000)
BIOL 1001A (1,000)
Tom Haffie (1,000)
Lecture 9

Biology 1001A Lecture Notes - Lecture 9: Reverse Transcriptase, Inverted Repeat, Retrotransposon


Department
Biology
Course Code
BIOL 1001A
Professor
Tom Haffie
Lecture
9

This preview shows page 1. to view the full 5 pages of the document.
Lecture'9:'Origin'of'Variation'
Independent'Study'Outcomes'
1.'Differences'among'insertion'sequences,'transposons'and'retrotransposons'
Mobile'Elements:'particular'segments'of'DNA'that'can'move'from'one'place'to'another;'they'cut'and'
paste'DNA'backbones'using'a'type'of'recombination'that'does'not'require'homology''
Transposable'Elements'(TE’s):'more'specific'term'for'mobile'elements''
o Bacterial'TE’s'
§ Insertion'Sequences:'the'simplest'TE’s.'Relatively'small'and'contain'only'genes'for'their'
transposition,'notably'the'gene'for'transposase:'an'enzyme'for'catalyzing'some'
recombination'reactions'for'inserting'or'removing'the'TE'from'DNA'
- A'short'inverted'repeat'sequence'–'the'same'DNA'just'running'in'opposite'
directions'
- This'inverted'repeat'sequence'enables'transposase'enzyme'to'identify'ends'of'TE'
when'It'catalyzes'transposition''
'
'
'
'
'
'
§ Transposons:'has'an'inverted'repeat'sequence'at'each'end'enclosing'a'central'region'
with'one'or'more'genes.'
- Inverted'repeat'sequences'are'often'insertion'sequences'which'provide'transposase'
for'movement'of'the'element'
- Additional'genes'in'central'region'typically'code'for'antibiotic'resistance'
- Non'IS'genes'included'in'transposons'are'carried'along'as'the'TE'moves'form'place'
to'place''
'
'
'
'
'
'
'
o Eukaryotic'TE’s'
§ Eukaryotic'Transposons:'similar'to'bacterial'transposons'in'structure'&'how'they'
transpose''
§ Retrotransposons:'transpose'by'a'copy'and'paste'mechanism'(unlike'any'other'TE'
discussed'here)''
- Called'retrotransposons'because'transposition'occurs'via'an'intermediate'RNA'copy'
of'the'TE''
HOW?'
- Retrotransposon'integrated'into'chromosomal'DNA,'then'transcribed'into'a'
complimentary'RNA'copy.'Reverse'transcriptase,'which'is'encoded'by'one'of'
You're Reading a Preview

Unlock to view full version

Only page 1 are available for preview. Some parts have been intentionally blurred.

the'genes'of'the'retrotransposon,'uses'the'RNA'as'a'template'to'make'a'
DNA'copy'of'the'retrotransposon.'The'DNA'copy'is'inserted'into'DNA'at'a'
new'location,'leaving'the'original'in'its'place.'''
- Similar'to'retroviruses'because'ones'TE'is'inserted'into'the'chromosome,'it'
is'duplicated'and'passed'during'cell'division''if'inserted'into'DNA'of'
reproductive'cells'–'may'be'inherited,'or'become'part'of'the'genetic'
material'of'the'species''
'
'
'
'
'
'
'
'
'
'
'
'
'
'
'
'
'
'
'
'
'
You're Reading a Preview

Unlock to view full version