The eukaryotic genome Flashcards
How does organization of genes differ in prokaryotes vs eukaryotes
- It appears eukaryotes have more DNA than needed to encode all their genes, prokaryotes don’t
What is an exon?
The part of the DNA sequence that actually encodes a protein
What is an intron?
The part of DNA that doesn’t actually encode a gene; it’s the “gibberish” in the code
Explain how introns are dealt with in the eukaryotic genome, what catalyzes this?
- Introns are removed by “splicing”, and the exons join together
- This reaction is catalyzed by snRNPs
How do snRNPs work?
- snRNPs are able to recognize specific sequences- they bind to these sites; intron is “snipped out”
- A guanosine cap is added to 5’ end to stabilize the tail
- Poly A tail is aded to 3’ end
Where do the removed introns go?
The enzyme Telomerase adds single intron strand that is complementary to the RNA to the gaps on the lagging strand. (Gaps are due to lack of 3’ OH)
Why is it important for introns to attach to lagging strand? What would happen if they didn’t?
The lagging strand has multiple gaps throughout it due to the lack of a 3’ OH.
If introns did not fill the end of the gap, then the DNA strand would shorten with every round of replication
What is Telomerase?
Telomerase is the enzyme that adds introns to the guide RNA
What is a Transposable element?
Elements the “hop around the genome”, altering the cells genetic identity
What are Retrotransposons?
Proteins that make copies of themselves using reverse transcriptase. (reinserting into genome)
What is an “Alu” element?
Alu elements are elements that rely on reverse transcriptase produced by other elements so they can jump,
they are one of the msot abundant transposable elements
What are DNA transposons?
DNA transposons splice themselves out of genome then back in- they have little purpose
What are pseudogenes?
Genes made when mRNA is reverse transcribed and inserted into genome
What are Ribozymes?
RNA enzymes- they are a stretch of RNA that can self-splice introns
