DNA Enzymes Flashcards
What do polymerases catalyse?
The condensation synthesis of DNA and RNA nucleic acid polymers. Catalyses the formation of phosphodiester bonds between a nucleotide and the nucleic acid of a newly synthesised strand.
What organises the nucleotides into the correct order?
H-bonding between complementary pairs of monomer nucleotides and the base sequence of a template strand.
Why are short single stranded complementary sequences needed?
Polymerases only catalyse the addition of polymers onto the end of a strand.
Where can you find a thermostable DNA polymerase?
A hot-spring bacterium
When must a thermostable DNA polymerase be used?
In cyclic reactions involved in PCR and DNA sequencing
What does Ligase do?
It catalyses the condensation synthesis of phosphodiester bonds between two strands of nucleic acid polymer.
What do endonucleases do?
Catalyse the hydrolytic degradation of phosphodiester bonds. They catalyse the complete breakdown of nucleic acid polymers into nucleotide monomers
Where do restriction enzymes cut?
Between a specific sequence of nucleotide bases
How is a sticky end formed?
When the restriction enzyme hydrolyses a phosphodiester bond on both strands several pairs apart.
What is an advantage of blunt ends?
They can be joined to any other blunt end fragment.
Give an advantage of sticky ends?
They will only form complementary base pairs with a fragment cut by the same restriction enzyme.
What are plasmids ideal for?
Vectors for the movement of genes between cells in the laboratory.
The manufacture of recombinant DNA.
Transforming prokaryotic cells to produce useful proteins.
Libraries to store fragments of DNA fragments in both prokaryotic and yeast cells
What is recombinant DNA?
Combinations of genes or DNA that would not occur naturally.
What is used to seal fragments of DNA into a plasmid?
Ligase.
How can engineered plasmids be selected easily?
Adding genes to the plasmid, which code for antibiotic resistance or a fluorescent protein.
