11.1 Flashcards
why are type I restriction endonuclease special?
they can recognize and cleave specific DNA sequences (recognize and cleave somewhere else)
when were type I restriction endonuclease descovered?
1960s
what is special about type II restriction endonucleases?
they cleave within the recognition site
when were type II restriction endonuclease first reported?
1970
what is a palindromic sequence?
sequence on nucleotides that are the same if they both go in the same direction
example:
5’ GAATTC 3’
3’ CTTAAG 5’
how are type II restriction endonuclease named?
derived from species name, stain, and order they were isolated
why don’t bacterial restriction endonuclease attack their own DNA?
most commonly - host methylates a base in every copy of RE site in their genome
how do restriction endonucleases work?
cleave leaving sticky ends that ligase can put back together differently
what is gel electrophoresis?
method for sorting DNA and RNA fragments by size
what happens to DNA segments in gel electrophoresis?
smaller ones move quicker/farther through the gel towards the + electrode
what is the charge of DNA molecules?
negative, because of the phosphate groups
how do you visualize DNA molecules in gel electrophoresis?
DNA-binding fluorescent dye (usually bind in minor groove)
what factors may affect mobility of DNA fragments in gel other than size?
agarose concentration
topology of DNA molecule
voltage
how does concentration of agarose affect gel electrophoresis
pore size increases with agarose
smaller pores are resistant to DNA movement (gives better resolution of size differences)
how does DNA topology affect gel electrophoresis?
relaxed circular DNA if fastest, then linear, then supercoiled ciruclar
