Restriction Endonucleases

Question 1

What are Restriction endonucleases?

Answer 1

Naturally occurring bacterial enzymes, a defence against viruses.

Question 2

What are restriction enzymes?

Answer 2

An enzyme isolated from bacteria that cuts DNA molecules at specific sequences.

Question 3

How many restriction enzymes has been discovered?

Answer 3

3000

Question 4

What ends does EcoRi enzyme has?

Answer 4

Sticky Ends (|____ —–|)

Question 5

Sticky Ends

Answer 5

EcoRi

Question 6

What ends does SmaI enzyme has?

Answer 6

Blunt ends ( | |)

Question 7

Blunt ends

Answer 7

SmaI Enzyme

Question 8

What makes blunt ends?

Answer 8

Alul, Haelll

Question 9

What makes sticky ends?

Answer 9

BamHI, HindIII, EcoRI

Question 10

Polymerase Chain Reaction

Answer 10

enables scientists to create vast quantities of DNA identical to trace samples.

Question 11

Process of Polymerase Chain Reaction

Answer 11

Target DNA, Taq polymerase, Primers

Question 12

Target DNA

Answer 12

the DNA sequence to be amplified (放大的).

Question 13

Taq polymerase

Answer 13

A type of enzyme that builds DNA strands, can withstand high temperatures

Question 14

Primers

Answer 14

Two artificially synthesised short sequences (about 20 nucleotides)
Complementary to the sequences either end of the target.
Needed by Taq polymerase as starting points for the building of new strands.

Question 15

3 stages of Polymerase Chain Reaction process

Answer 15

Denaturation, Annealing, Extention

Question 16

Denaturation

Question 17

Annealing

Answer 17

The temperature is reduced to ~55C, allowing artificially synthesised primers to anneal to the templates either side of the target sequence.

     --------------------
           Reverse primer---- -----Forward primer
     ---------------------

Question 18

Extension

Answer 18

The temperature is raised to 72C to allow Taq polymerase to copy each template strand using free nucleotides, starting from each primer.
The cycle is repeated at least 25 times