DNA sequencing and analysis

Question 1

What is DNA sequencing?

Answer 1

the process of determining the precise order of nucleotides within a DNA molecule

Question 2

What is a terminator base?

Answer 2

modified nucleotides that stop DNA synthesis when added to the sequence and they have a fluorescent tag so they can be identified

Question 3

What is in the mixture for DNA sequencing?

Answer 3

DNA for sequencing, primer, DNA polymerase, an excess of normal nucleotides and terminator bases

Question 4

What is the process for creating loads of different lengths of DNA strands?

Answer 4

the mixture undergoes PCR producing many strands of DNA. When a terminator base is added, DNA synthesis is terminated

Question 5

How are many different lengths of DNA bases made?

Answer 5

there a fewer terminator bases which are randomly added producing many different lengths of fragments. After many cycles all possible DNA chains will be produced.

Question 6

How are the fragments separated?

Answer 6

separated according to their length by capillary electrophoresis.

Question 7

How is the order of bases in DNA strand identified?

Answer 7

fluorescent markers on the terminator bases can be identified using lasers to detect the different colours and they are the last bases on each strand so when identified in size order, you can work out the order of bases for the whole complementary strand

Question 8

What is next generation sequencing?

Answer 8

sequencing reaction takes place on a flow cell where millions of fragments are attached and replicated using PCR forming clusters of identical fragments. All clusters can be sequenced and imaged at the same time