L7 Flashcards
who disovered TEs
Mclintock
what is a TE
genes that can jump; mobile genetic elements
what are the three types of repeat DNA
direct, inverted, palindrome
true or false, inverted repeats can assume cruciform structures by intra strand base pairing
true
how are lollipops formed
formed by long inverted repeats
what are 3 classes of bacterial transposable elements
- ) insertion sequences; small no phenotype
- ) transposons; large carry bacterial genome
- ) Bacteriophage Mu(tator); large complex virus, not considered
what were the cause of polar mutations
insertions sequences
what are the properties of insertion sequences
- called IS1 and IS2
- small,0.5-2kb long
- contain inverted repeats at their termini which sometimes extend over their whole length
- encode one protein, the transposase enzyme that is involved in their movement
what are the properties of transposons
- code for an enzyme called transposase
- transposes bind to the inverted repeats as the termini of TEs and mediate movement of the element to new sites of the genome
- many different kinds of enzyme, that move with different mechanisms
- preferred target sites can vary from random to highly specific
true or false, transpose enzyme makes staggered nicks at insertion site
true
true or false, transposition always generates short direct repeats at the insertion site
true
what are the two kinds of transposition
replicative and non replicative
what is replicative transposition
excision and movement, original is gone
what is non replicative transposition
copying and movement, original remains
what are the properties of bacterial TE
- small DNA elements (0.2-10 kb) able to tranpose
- found in different locations in different genomes
- encode transposase and sometimes additional genomes
- flanked by IR binding site for transposase
- generate short direct repeats of characteristic length at insertion site
- replicative or conservative transposition
