Topic 4 - Gene Technology

Question 1

What is the PCR

Answer 1

Polymerase chain reaction is used to amplify target DNA sequences that are present in a DNA source

Question 2

What is required for the PCR

Answer 2

A DNA sample that includes the selected region for replication
The synthesis of primers
The enzyme DNA polymerase
Free doxyribonucleotides

Question 3

What is the process of the PCR

Answer 3

1. Select and isolate a piece of DNA to be copied
2. Raise temperature to 95°C to separate the two strands
3. Add primers, polymerase and nucleotides
4. Lower temperature slowly to 53°C to allow primers to bind to DNA
5. Raise temperature to 72°C to enable thermos table polymerase to replicate DNA
6. Repeat cycle of temperature changes 20 times

Question 4

What is the use of PCR

Answer 4

To study minute samples of DNA, and may be used in genetic fingerprinting

Question 5

What are micro satellite repeat sequences used for

Answer 5

Genetic markers in DNA fingerprinting since the pattern of repeat sequences in any individual is unique

Question 6

What are genetic markers

Answer 6

DNA sequences which are points of variation and so used to identify individuals

Question 7

What is the function of restriction endonucleases

Answer 7

They cut the sugar-phosphate backbone of DNA at specific nucleotide sequences. They cut DNA at a specific base sequence leaving blunt or sticky ends

Question 8

What is the function of a DNA probe

Answer 8

It is used to located a particular section of DNA

Question 9

How does a DNA probe work

Answer 9

It anneals by base paring to a complementary region of single-stranded target DNA

Question 10

What are the stages of genetic fingerprinting

Answer 10

1. Extract DNA from a sample
2. Using restriction enzymes to cut out repeated sequences
3. Use gel electrophoresis to separate DNA fragments
4. Transfer the DNA fragments onto a nylon sheet
5. Attach labelled probes
6. Detect the different repeat sequences

Question 11

What are the main type of vectors in gene transfer

Answer 11

Plasmids and viruses

Question 12

How is donor DNA and bacterial plasmid made complementary

Answer 12

If bacterial plasmid and the donor DNA is cut using the same restriction endonuclease, it will mean that they have complementary sticky ends

Question 13

What is the process of using plasmid as vectors

Answer 13

1. The bacterial plasmid and donor DNA is cut using the same restriction endonuclease to have complementary sticky ends
2. The bases pair up and DNA ligand joins the DNA backbones together through phosphodiester bonds
3. The end result is the donor DNA is spliced into the plasmid which becomes a close loop again

Question 14

How has the Plasmid DNA changed following gene transfer

Answer 14

It contains ‘foreign’ DNA from another source, and so is referred to as recombinant DNA

Question 15

What is the process of viruses as plasmids

Answer 15

Viruses are adapted to ‘shoot’ their genetic material into a host cell. A bacteriophage can have donor DNA spliced into its DNA with the result that the donor DNA will also be fired into the host cell