Hybridisation

Question 1

hyperchromic effect

Answer 1

when DNA denatures, causing its UV absorbance to increase by ~40% at all wavelengths

Question 2

Tm = melting temperature of DNA

Answer 2

increases with: increasing G-C content, increasing Na_ concentration, increasing length of hybrid, decreasing formamide (a solvent) concetration

Question 3

All DNA melts at less than:

Answer 3

100 C

Question 4

Tm (C) =

Answer 4

81.5 + 0.41 x (%G-C) + 16.6log[Na+] - 0.63 x (% formamide) - (600/length)

Question 5

Tm (C) =

Answer 5

4 x (no. of G & C) + 2 x (no. of A & T)

Question 6

hybridisation

Answer 6

formation of double-stranded helix or hybrid, usually between a probe & its complementary target

Question 7

Stability of hybrids

Answer 7

1-RNA/RNA. 2-DNA/RNA. 3-DNA/DNA.

Question 8

Low stringency

Answer 8

temperature of hybridisation much lower than TM for perfect match

Question 9

High stringency

Answer 9

temperature of hybridisation closer to TM for perfect match

Question 10

renaturation of DNA: total number of target molecules =

Answer 10

number of DNA molecules x number of repeats