Duplex stability

Question 1

Duplex stability

Answer 1

the more -ve delta G = more stable the duplex as hybridisation is favourable
all base pairs are enthalpically favoured and entropically disfavoured

Question 2

Calculation delta G

Answer 2

begin with the terminal base pair and read along to the right. assign the values given according to what is next to it.

Question 3

the duplex’s response to temperature

Answer 3

increase in temperature reduces stability
stored in low temps to prevent breakdown

Question 4

the duplex’s response to salt concentration

Answer 4

increase in salt = pushes up the melting temp and increases stability
M2+ more strongly stabilising than M+

Question 5

the duplex’s response to pH

Answer 5

neutral = stable, all H bonds intact
lower pH = less stable, more H+ around so begins to protonate
higher pH = less stable, less H bonds intact, deprotonates

Question 6

chemical denaturation

Answer 6

done by chemicals that compete for H bond sites