UNIT 3 3A: Common DNA tools and Techniques

Question 1

Restriction Enzyme

Answer 1

A bacterially produced protein that cuts DNA at a specific sequence of nucleotides called a recognition site; also known as a restriction endonuclease

Question 2

Recognition (restriction) Site

Answer 2

A specific sequence of nucleotides that is the location for a restriction enzyme to cut

Question 3

Digestion

Answer 3

(in the context of restriction enzymes) a reaction using an enzyme to break down large molecules

Question 4

Sticky Ends

Answer 4

Short lengths of unpaired nucleotides in DNA resulting from a staggered cut by a restriction enzyme

Question 5

Blunt ends

Answer 5

Short lengths of fully paired nucleotides in DNA resulting from a straight cut by a restriction enzyme

Question 6

Palindrome

Answer 6

A sequence that reads the same in both directions

Question 7

DNA ligase

Answer 7

An enzyme which joins the phosphodiester backbones of adjacent DNA nucleotides

Question 8

Polymeraze chain reaction (PCR)

Answer 8

A technique used to amplify a sample(template) of DNA

Question 9

Primer

Answer 9

Synthetic single-stranded piece of DNA (or RNA) complementary to a specific sequence of nucleotides.

Question 10

Gel electrophoresis

Answer 10

A technique used to separate different sized fragments of DNA (or protein)

Question 11

DNA Standard

Answer 11

A DNA sample that contains fragments of DNA of known size
that is used to compare the sizes of unkown DNA fragments in base pairs or kilo base paires; also known as a DNA ladder

Question 12

Why can RNA Polymerase not be used in PCR?

Answer 12

The purpose of DNA polymerase is to create a copy of the original DNA template. RNA polymerase would create a single-stranded mRNA strand, which is not needed in the PCR process.

Question 13

Why is DNA taq polymerase specifically required in the process of PCR

Answer 13

DNA “taq” polymerase is specifically used as it can work in high temperatures with high efficiency and amplification capacity, whereas other DNA polymerase enzymes may not be able to work in these environments.

Question 14

Key ingredients in PCR

Answer 14

1.DNA template
2. Forward and reverse primers
3. Free Nucleotides
4. Heat resistant DNA polymerase (DNA taq polymerase)

Question 15

Stages of PCR

Answer 15

1. Denaturation
2. Annealing
3. Extension (elongation)

Question 16

Denaturation

(In PCR), description + specific temperature

Answer 16

Heating separates the DNA strands by breaking hydrogen bonds between complementary base pairs.
95*C

Question 17

Annealing

Description + Specific temperature

Answer 17

Cooling allows primers to bind to the complementary regions of the remplate DNA through hydrogen bonding

At the opposite end of each strand, marking the start regions of transcription for each DNA strand

Occurs at 55*C

Question 18

Extension (elongation)

Answer 18

DNA taq polymerase binds to each primer and moves along each strand of the Template DNA, adding free nucleotides through complementary base pairing. This creates two copies of the original DNA template.