4A - Enzymes that manipulate DNA

Endonuclease

Restriction enzymes that cut DNA at specific recognition sequences, cleaving the phosphodiester backbone of the sugar phosphate backbone.

Ligase

Enzymes that facilitate joining of DNA strands by catalysing formation of phosphodiester bonds between two strands.

Polymerase

Enzymes that attatch to a primer on a template strand and synthese polymer chains from monomer building blocks, such as RNA polymerase and DNA polymerase.

RNA polymerase

Enzyme that synthesises RNA polymer from RNA nucleotide monomers,

primer

short single stranded chain of nucleotides complementary to a template strand which polymerase attatches to and can read and synthesise a complementary strand in a 5’ to 3’ direction

Restriction enzymes

Cut DNA at specific recognition sites, creating blunt or sticky ends

Recognition site

palyndromic 4-6 nucleotide long target sequence upon which a specific restriction enzyme acts on

Blunt End

Endonuclease recognises and cuts through the middle of the recognition site, resulting in a straight cut with no overhanging nucleotides

sticky end

Endonuclease create a staggered cut with overhanging, unpaired nucleotides which are attracted to a complementary set of unpaired nucleotides