What do restriction enzymes do?
Reveal answer
Cut DNA at specific sequences → sticky ends.
Key words: sticky
6(c) GENETIC MODIFICATION (GENETIC ENGINEERING) · RECALL
6.12 Restriction enzymes and ligase
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What does ligase do?
Reveal answer
Joins DNA fragments.
Key words: joins
What is meant by the term restriction enzyme?
Reveal answer
An enzyme that cuts DNA at a specific base sequence.
Key words: restriction enzyme
What is meant by the term sticky ends?
Reveal answer
Short single-stranded overhangs of unpaired bases left after a staggered cut.
Key words: sticky ends
What is meant by the term DNA ligase?
Reveal answer
An enzyme that joins pieces of DNA together.
Key words: DNA ligase
What is meant by the term recombinant DNA?
Reveal answer
DNA made by combining DNA from two different sources.
Key words: recombinant DNA
Enzymes in genetic modification: for Restriction enzyme, give the role and the result.
Reveal answer
Role: Cuts DNA at a specific recognition site. Result: DNA fragments, often with sticky ends.
Key words: Restriction enzyme
Enzymes in genetic modification: for DNA ligase, give the role and the result.
Reveal answer
Role: Joins sugar–phosphate backbones. Result: A continuous recombinant DNA molecule.
Key words: DNA ligase
Enzymes in genetic modification: for Same restriction enzyme on both DNAs, give the role and the result.
Reveal answer
Role: Produces matching sticky ends. Result: Gene and vector ends can pair.
Key words: Same restriction enzyme on both DNAs
True or false, and why? “Restriction enzymes cut DNA randomly.”
Reveal answer
False. They cut only at their specific recognition sequence.
True or false, and why? “Ligase cuts the gene out.”
Reveal answer
False. Restriction enzymes cut; ligase joins.
True or false, and why? “Any two sticky ends will join.”
Reveal answer
False. Ends must have complementary bases, usually by using the same restriction enzyme.
Where in the DNA does DNA ligase form new bonds?
Reveal answer
In the sugar–phosphate backbone.
Key words: sugar–phosphate
How do sticky ends help two pieces of DNA join?
Reveal answer
Unpaired bases are complementary → pair with the matching sticky end → ligase seals the join.
Key words: complementary
What is a recognition site?
Reveal answer
The specific base sequence at which a restriction enzyme cuts.
Key words: base sequence