bio 4A Flashcards
enzymes that manipulate DNA
what are endonuclease
an enzyme that cleaves the phosphodiester bond between two nucleotides (sugar-phosphate backbone)
what are restriction endonuclease
an enzyme that acts as molecular DNA to cut nucleic strands at specific recognition sites
what are sticky and blunt ends
they are cuts created by restriction endonuclease. sticky ends refer to the cut creating staggered cuts with overhanging, unpaired nucleotides on either side. blunt ends refer to the cut of DNA being in the middle (no overhanging pairs)
why are sticky ends better than blunt ends
sticky ends mean the cuts create staggered, unpaired nucleotides that are able to pair with a complementary set of nucleotides which ensures a gene is inserted oriented correctly.
what are recognition sites
specific target sequences of DNA where restriction endonuclease act (typically palindromes and consist of 4-6 nucleotides)
what is ligase and its role
an enzyme that joins molecules together by catalysing the formation of phosphodiester bonds (acts as molecular glue - reverse of endonuclease) as it joins blunt and sticky ends back together
what is polymerase
an enzyme that synthesises a polymer from a monomer
what is the role of RNA polymerase
to turn RNA nucleotides to RNA strands
what is the role of DNA polymerase
to turn DNA molecules to DNA strands (from template strand and free nucleotides attach and form the new strand)
what is a primer and its role
a short, single strand of nucleic acids that act as a starting point for polymerase enzymes to attach
why is DNA formed from RNA
this is because DNA is found in the nucleus and cannot be taken out as it is the original copy whereas creating DNA from RNA means that there is no harm in taking it as RNA is the copy n
