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AS/A2 BIOLOGY > DNA Technology > Flashcards

Flashcards in DNA Technology Deck (23)
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1
Q

What is recombinant DNA?

A

The combined DNA of two different organisms

2
Q

What is the process of using reverse transcriptase?

A

Reverse transcriptase catalyses DNA production from RNA

1) A host cell with desired protein is selected
2) Reverse transcriptase produces DNA from the mRNA in the host cell
3) Complementary DNA is produced (cDNA)
4) DNA polymerase forms a double helix

3
Q

What do restriction endonucleases do?

A

The cut a double stand of segment of DNA at a specific recognition sequence

4
Q

What is a recognition sequence?

A

A 6 base sequence that is read the same both forwards and backwards i.e. a palindrome

5
Q

What is a vector?

A

A means of transporting DNA to the host cell

6
Q

Which enzyme is used to join the sugar phosphate backbone?

A

DNA Ligase (DNA polymerase bind the nucleotides together)

7
Q

What is the process of transformation?

A

It involves the plasmids and bacterial cells being mixed together in a medium containing Ca2+ ions

8
Q

How do you check which bacterial cells have taken up the vector?

A

1) Grow all bacterial cells in a medium containing ampicillin
2) Any cells which survive will have taken up the plasmid containing a gene for ampicillin resistance
3) Only bacteria that have taken up the plasmid will survive

9
Q

How do you insure which bacterial cells have both ampicillin and tetracycline resistance?

A

1) The original surviving cells are cultured on an agar plate
2) A tiny sample of each colony is placed on a different plate in the exact same position
3) Plate 2 will contain tetracycline
4) The colonies not killed on plate 2 will be those which contained the modified gene

10
Q

What are 2 other ways of identifying the desired species?

A

1) Fluorescent markers- using GFP

2) Enzyme markers- using lactase which turns are desired substrate blue

11
Q

What is DNA polymerase and why is it used in PCR?

A

An enzyme that joins nucleotides, used as it doesn’t denature at high temperatures

12
Q

What is a primer?

A

Short sequence of bases, complementary to those as the end pf a DNA strand

13
Q

What is the process of PCR?

A

1) The DNA sample, DNA polymerase and primers are placed in the machine and heated to around 95 degrees which separates the DNA stand.
2) Cool the mixture to around 55 degrees which allows the primers to join with their complementary bases.
3) Raise temperature to optimum of DNA polymerase around 70 degrees which will join up nucleotides between the primer and the end of the DNA molecule.
4) Cycle is repeated and each cycle yield double the amount of DNA.

14
Q

What are some advantages and disadvantages of in vivo (vectors)?

A
Advantages 
1) Very accurate 
2) Produces useful GM products (vaccines)
3) Little risk of contamination
Disadvantages
1) Could harm the host
2) Host may not take up the vector
3) Detection may fail
15
Q

What are some uses of DNA technology?

A

1) GM of crops i.e. increase in yield
2) Medicinal i.e. antibiotics, enzymes, hormones
3) GM animals

16
Q

What is cystic fibrosis and how is it caused?

A

A disorder where epithelial membranes become defective and secrete thick heavy mucus. It is caused by a deletion mutation.

17
Q

What are the treatments for CTFR using gene therapy?

A

1) Gene replacement
2) Gene supplementation- adding copies of the healthy gene alongside the defective one but the healthy gene is dominant.
3) Germline cell therapy- replacing the defective gene whilst in the fertilised egg so all daughter cells will have the healthy gene.
4) Somatic cell therapy- targets only the affected tissue and so cannot be passed to offspring. This treatment is not permeant.

18
Q

How do you deliver CTFR genes?

A

Use adenovirus as the host, which takes up the normal CF gene as a vector.

19
Q

How do the CF genes pass the phospholipid bilayer?

A

The genes are wrapped in lipid molecules forming a liposome

20
Q

What is DNA hybridisation?

A

The use of a DNA probe attached to a radioactive label with a complementary sequence to the gene you wish to identify.

21
Q

What is gel electrophoresis?

A

The technique used to separate DNA fragments in order of length.

22
Q

What is restriction mapping?

A

Electrophoresis only works for short fragments of DNA, therefore DNA must be cut my restriction enzymes

23
Q

What are the 5 stages of genetic fingerprinting?

A

1) Extraction and amplification of DNA
2) Digestion- uses restriction enzymes which will isolate core sequences
3) Separation- uses of electrophoresis to separate fragments
4) Hybridisation- complementary DNA probes to the core sequences are added
5) Development- X-ray films