Lambda and Alternative Vectors Flashcards
What is cDNA?
mRNA that has been reverse transcribed to DNA with no introns (only exons).
Stands for Complementary DNA
How is cDNA usually cloned?
Using plasmids as they are generally short pieces of DNA.
How is eukaryotic genomic DNA usually cloned?
Using x amount of plasmids to create a library of information with chunks of DNA in
As gDNA is too big to be cloned into a single vector.
What is a phagemid?
a plasmid with f1 phage origin. Replicates as a plasmid and packages as a single stranded DNA
What is a cosmid?
a plasmid with a cohesive end
sequence from I phage to allow I phage packaging
What is a fosmid?
uses an F plasmid or fertility plasmid that encodes for protein that contains a pilus
What is a tailed bacteriophage?
Allow for binding to the cell surface and injection of genome directly into host cell (looks abit like a spider robot).
They have a lytic life cycle- take over the function of the cell and kill the cell in the process.
How does bacteriophage Lambda infect E.coli?
Via the maltose transporter.
Lambda binds to the E.coli maltose transporter
Injects the linear DNA into the host cell
After infection, lambda DNA circularises at cos sites (complementary sites that are sticky ends)
Replicates by the rolling circle method
What is essential if lambda is to be used as a vector?
Distance between the 2 cos sites must be between 35kb and 53 kb so that it is wide enough to fit in the fragment DNA but not too short so the fragment doesn’t fit.
What are YACs?
Yeast Artificial Chromosomes
Useful for copying large sequences
But very low transformation efficiency and DNA yield (about 1-2 molecules per cell)
