Module 6: DNA sequencing techniques Flashcards
(8 cards)
DNA sequencing is the …
process of determining the exact nucleotide sequence within a DNA molecule
Sanger sequencing is a technique used for DNA sequencing , what does it rely on ?
2 things
radioactive labelling of bases and a process called gel electrophoresis
Give two improvements of the Sanger sequencing technique that have been made
-use of fluorescent tags instead of radioactive ones to increase safety and efficiency
-introduction of capillary sequencing (key method used in the Human Genome Project)
DNA sequencing key steps: First 2 points
What 4 things is DNA mixed with?
What happens to double stranded DNA?
1)DNA mixed with primers , DNA polymerase , nucleotide bases and terminator bases
2)Double stranded DNA is split into single strands and copied multiple times
DNA sequencing key steps:Points 3 and 4
What does DNA polymerase do once single stranded DNA has been formed?
What happens when a terminator base is reached?
3)DNA polymerase adds nucleotides to the single stranded template to start rebuilding new DNA strands
4)When a terminator base is reached , DNA synthesis stops and each is tagged with a unique fluorescent colour
DNA sequencing key points: Points 5 and 6
What is produced as a result of the following 4 steps?
How are fragments then separated?
5)This produces DNA fragments of all possible lengths
6)These fragments are separated by length using either capillary sequencing or gel electrophoresis
DNA sequencing key points: Points 7 and 8
What is used to detect the fluorescent colour of each terminator base and what does this determine?
With every potential base marked , what is then done?
7)A laser is used to detect the fluorescent colours of the terminator bases in each fragment to determine their sequence order
8)Computer software analyses the fragments to reconstruct the original DNA sequence
DNA sequencing plays a crucial role in what?
accurate identification of genetic disorders and cancers
