Techniques Flashcards
how can DNA be visualised on agarose gel?
add ethidium bromide.
what do bacteria make along with their own restriction enzymes?
sequence specific methylases - adds methyl group to restriction site to block cleavage.
what can restriction enzyme mapping be used for?
detect individual differences or mutations (if change in DNA sequence is at restriction site - different length fragments produced).
what is the function of cloning vectors?
(plasmids) carry DNA fragments into host (i.e. bacteria)
what is a feature plasmids used for DNA cloning?
multiple INDIVIDUAL restriction sites clustered in multiple cloning site where DNA inserts can be cloned.
why is PCR useful?
alternative method of making clones of specific DNA fragments without need of a cloning vector.
what are the four different types of vectors? What trend do they show?
plasmids, bacteriophages, cosmids, artificial chromosomes - can carry increasing amounts of DNA.
what sequences are contained in yeast artificial chromosomes?
centromeric and telomeric
why is mRNA and not genomic DNA useful dor cloning?
no introns, single, long open reading frame for protein.
small & easily handled.
why are three reading frames required?
need shine dalgarno (ribosome binding site) closely followed by start codon
only one rf contains binding site close to start codon.
