Question

PCR

7- Genomes are frequently described according to their GC content. G (guanine) and C (cytosine) make triple hydrogen bonds in the double helix, whereas thymine and adenine make double hydrogen bonds. Would you expect to program a thermal cycle the same way for an organism with 50% GC as an organism with 25% GC? If yes, why? If not, what would you change?

8- What molecules are present in the cell that might interfere with DNA extraction?

Answer 1

7. The GC content of genomes interferes with denaturation of DNA duplex.
High GC content = High melting temperature
Low GC content = Low melting temperature
The first step of PCR involves denaturation (Separation of two DNA strands of the duplex).
So, if the given template DNA has high GC content, we either have to increase the denaturation temperature or denaturation.
Sometimes, we have to adjust the annealing temperature as well.

8. DNA extraction from a cell can be affected by multiple factors such as
i. Presence of carbohydrates (Such as plant cells)
ii. Presence of specific DNA binding proteins
iii. Presence of specific lipids that alter the property of extraction reagents