Topic 15.3: DNA sequencing

Question 1

what is 2,3 dideoxy analog

Answer 1

2,3 - dideoxy analog (H on 2 and 3) - recognised by DNA polymerase due to 2 prime Hydrogen which can be added with phosphodiester bond but no 3 prime hydroxyl so will stop elongation

Question 2

how does DNA sequencing work

Answer 2

add specific primers to DNA sequence
add DNA polymerase, unlabelled nucelotides, fluorescently labelled dideoxy analogs
separate strand and allow DNA polymerase to work to make copy of template
results in a mixture of different sequences depending on when a labelled dideoxy analog introduced instead of nucleotide and chain has terminated
these are separated using capillary electrophoresis and able to detect fluorescentally labelled molecules. this is sequence of template strand