3.14 - Restriction Enzymes

Question 1

What are restriction enzymes?

Answer 1

They are enzymes that have the ability to cut strands of DNA a part.
They are said to be a defense mechanism against viruses.

Think like moleculare sicssors

Question 2

Where do restriction enzymes originate from?

Answer 2

They originated from bacteria

Question 3

True or False:

Restriction enzymes have a recognition site.

Answer 3

True
The recognition site is specific to the nucleotide sequence the enzymes binds with. If there is no recognition site, the enzyme cannot cut

Question 4

What are two types ends that are a result of restriction enzymes?
Describe them.

Answer 4

1) Sticky ends- the DNA is cut on an angle, which creates one smaller and one larger (an overhang) piece. This makes it easier for complentary DNA to attach
2) Blunt ends- the DNA is cut in a straight line, so no overhangs. these ends are harder to join together.

Question 5

What is recombinant DNA?

Answer 5

• refers to any 2 pieces of DNA that have been joined together but come from different sources
• recombinant DNA can be artifically created through restriction enzymes and genetic engineering

Question 6

How is recombinant DNA achieved?

Answer 6

• Two different genes are cut as a result of Restriction enzymes
• If both are complentary, they will come together and DNA ligase with seal them. This forms phosodiester bonds
• Side note: blunt ends are harder to rejoin. It is done with the help of Ty-DNA ligase which then forms a bacteriophage virus

Question 7

What is “DNA fingerprinting”?

Answer 7

• RFLP: restriction fragment length polymorphism
• Gel electrophoresis [elec-tro-fore-e-sis]
• allows a DNA sample to be tested and traced back to the person it came from

Question 8

How does gel electrophoresis work?

Explain what happens when the lines on the gel are produced

Answer 8

• DNA samples are placed in wells at the topof the gel
• the top end is negative and the bottom is positive
• DNA fragments are negatively charged, which means that the DNA will move down the gel
• smaller pieces move faster than larger ones, which is why the scale is smaller towards the positive end

Question 9

How do you identify a suspect’s DNA on a gel?

Answer 9

look for which lines/fragments look the closest to the evidence collected

Question 10

How do you identify a child’s possible father on a gel?

Answer 10

• “cross out”/ identify the fragments that come from the mother’s DNA
• reference the child’s DNA with the man that shares the most number of fragments and that make up the rest of the child’s DNA