dna technology

Question 1

What does gene technology allow?

Answer 1

The study and alteration of gene function

Question 2

What does this allow?

Answer 2

A better understanding of organism function

Question 3

What are the ‘tools’ in DNA technology?

Answer 3

Restriction enzymes, electrophoresis, PCR, DNA primers and DNA probes

Question 4

What are restriction enzymes?

Answer 4

Hydrolyse phosphodiester bonds in DNA or RNA producing smaller fragments

Question 5

Where do they hydrolyse these bonds?

Answer 5

In both strands of DNA

Question 6

What is the name of specific base sequences they hydrolyse DNA or RNA from?

Answer 6

Recognition sequences/ recognition site

Question 7

What are sticky ends?

Answer 7

Where the DNA is hydrolysed at different locations of the strand

Question 8

What are blunt ends?

Answer 8

Where the DNA is hydrolysed at the same position on both strands

Question 9

Why do sticky ends make it easier for DNA to be joined or spliced onto a different piece of DNA?

Answer 9

Complimentary base pairing can happen between sticky ends

Question 10

What is gel electrophoresis?

Answer 10

Where smaller fragments will travel further and faster through gel when a charge is applied

Question 11

What is the charge of DNA?

Answer 11

Negatively charged

Question 12

What is the first stage of gel electrophoresis?

Answer 12

DNA samples are placed in separate wells at the top of the gel

Question 13

What is the next step in gel electrophoresis?

Answer 13

DNA fragments are separated according to size as smaller fragments move further

Question 14

What is the next step after separating DNA fragments?

Answer 14

DNA fragments are transferred to a nylon membrane and the radioactively labelled DNA probes are added

Question 15

What is the next step after transferring DNA fragments to a membrane?

Answer 15

Membrane is placed on X-ray or photographic film and position of the radioactively labelled fragments are revealed

Question 16

What is the appearance of radioactively labelled compounds known as?

Answer 16

Autoradiography

Question 17

What are DNA ladders?

Answer 17

Fragments of known sizes can be used to calculate the size of the DNA fragments

Question 18

What does PCR mean?

Answer 18

Polymerase chain reaction

Question 19

What does this technique do?

Answer 19

Enables multiple copies of identical fragments of DNA or genes to be produced from a small sample

Question 20

What is in the reaction mixture for PCR?

Answer 20

DNA to be copied, primers, free nucleotides, DNA polymerase

Question 21

What is the first stage of PCR?

Answer 21

Reactants are mixed at 95°C for 5 minutes

Question 22

What does this do in the first stage of PCR?

Answer 22

Breaks the hydrogen bonds in DNA

Question 23

What is the second stage of PCR?

Answer 23

Mixture is cooled to 50-60°C for 2 minutes

Question 24

What does this allow in the second stage of PCR?

Answer 24

Primers to join to their specific complementary target sequence

Question 25

What then happens after the second stage of PCR?

Answer 25

Free DNA nucleotides align to DNA strands by complimentary base pairing

Question 26

What is stage 3 of PCR?

Answer 26

Temperature is increased to 72°C which is the optimum for DNA polymerase

Question 27

What then happens in stage 3 of PCR?

Answer 27

Enzyme joins individual nucleotides of a strand together to form a new complementary strand

Question 28

What is the equation for molecules produced in PCR?

Answer 28

2^n when n= number of cycles

Question 29

What are DNA primers?

Answer 29

Short, single-stranded molecules of DNA

Question 30

What do they provide?

Answer 30

A starting sequence for DNA polymerase

Question 31

Why is this important?

Answer 31

DNA polymerase cannot begin at a single-stranded point, they help prevent the DNA strands from joining back together

Question 32

What are DNA probes?

Answer 32

Short, single-stranded molecules of DNA that are radioactively or fluorescently labelled

Question 33

What are they used for?

Answer 33

Identify or locate known sequences of DNA