Unit 17 - Transposition

What is transposition

specific form of genetic recombination that moves certain genetic elements from one DNA site to another within the same genome

True or false: transposition occurs within the same genome

true

True or false: transposition is NOT a major source of mutation

false

What are the two ways that transposition can occur?

with or without duplication

true or false: transposition may or may not involve duplication of transposon

true

true or false: the amount of transposons in various genome highly varies between species

true

What organism has about 85% transposon genes?

maize, or corn

What are the three principal classes of transposable elements?

DNA transposons, virus-like retrotransposons, poly-A retrotransposons

What type of transposons have RNA intermediates?

virus-like retrotransposons and poly-A retrotransposons

Terminal inverted repeats are ___________ sites

recombination

true or false: DNA transposons contain a transposase gene

true

What makes a transposon autonomous?

whether or not it encodes its own transposase

What two enzymes does the virus-like retrotransposon encode?

integrase and reverse transcriptase

What makes the virus-like retrotransposon different from a retrovirus?

it stays within its genome

What two enzymes are encoded by poly-A retrotransposons?

ORF1 and ORF2, which are RNA-binding enzyme and enzyme with reverse transcriptase and endonuclease activities

true or false: the two ends of the poly-A retrotransposons are the same

false

Describe cut-and-paste transposition

the transposase will bind to terminal inverted repeats which then make double strand break, which the 3'-OH can then attack the target DNA and insert, DNA-repair synthesis can then fill gaps, ligates the nicks

What are the three domains found in the integrase and transposase enzymes?

DNA binding domain, DDE domain, and protein-protein contact domain

What is the only domain that remains well-conserved in transposase?

catalytic domain

What is recombinase?

An enzyme that catalyzes site-specific recombination

What are the components of recombinase and their function?

RAG1 and RAG2 facilitate recombination between variable regions of antibody encoding genes

What do RAG1 and RAG2 function like?

transposases

What is RAG?

recombination activating gene

What is the V(D)J pathway?

process that enables the diversity of antibodies in vertebrate immunity, specifically in developing B cells

What plays a role in the V(D)J pathway?

recombinase

What are the product of the V(D)J recombination?

antigen binding sites