Gene Technology past paper questions

Question 1

How does restriction endonucleases cut DNA into smaller fragments

Answer 1

Cute DNA at specific base sequences along the sugar-phosphate backbone, producting either blunt or sticky ends

Question 2

How advantage does PCR offer to scientists

Answer 2

A large number of DNA copies can be synthesised from a single DNA sample

Question 3

How probes can be used to identify a section of DNA

Answer 3

DNA probes hybridise with complementary bases on the donor DNA, revealing the position of the required gene. The probe is labelled either radioactive or fluorescent, so can be identified.

Question 4

Why does the target DNA have to be single stranded to use a DNA probe

Answer 4

Exposed bases are required for binding
-If double stranded, there are no exposed bases

Question 5

Explain how foreign DNA is incorporated into a plasmid

Answer 5

The plasmid and DNA are cut using the same restriction endonuclease, forming complementary sticky ends. The DNA and plasmid are mixed together and complementary sticky ends form hydrogen bonds. They are annealed by DNA ligase, which catalyses the formation of phosphodiester bonds of DNA and plasmid