DNA Sequencing

Question 1

What is DNA sequencing?

Answer 1

-technique where we can map out the base sequence of an individuals genome

Question 2

What are the 5 things needed for DNA sequencing?

Answer 2

1. DNA sample to be sequenced
2. free nucleotides in excess
3. coloured fluorescent-labelled terminator bases
4. DNA polymerase
5. DNA primers

Question 3

What are the 4 steps to sequence a DNA strand?

Answer 3

1. heat up strand to 95 to denature DNA = 2 helixes
2. cool down to 50 - primers anneal
3. heat to 60 - DNA polymerase joins up nucleotides = new strand - but terminators present
4. electrophoresis or laser box

Question 4

What does electrophoresis do during DNA sequencing?

Answer 4

-direct UV light onto nylon membrane
-smaller = furthest = start of gene

Question 5

What happens during the laser box in DNA sequencing?

Answer 5

-shines laser as bases pass through
-produces the long stretch of bases

Question 6

What are terminator bases?

Answer 6

-have a H instead of a hydroxyl group at 3’ carbon of ribose
-can’t form phosphodiester bonds to the next

Question 7

What are the 2 other types of DNA sequencing?

Answer 7

1. nanopore
2. pyrosequencing

Question 8

What is nanopore sequencing?

Answer 8

-DNA strand is unwound through a protein channel
-causes a current that varies depending on the base
-computer can decode currents into sequences

Question 9

What is pyrosequencing?

Answer 9

-different bases are added individually and then removed

Question 10

What is an example of pyrosequencing?

Answer 10

-polymerase waits for a T
-when added the anime is active
-triggers luciferase = produces a flash that can be detected electronically
-2x lots = double the brightness