Module 8 - Gene technologies

Question 1

What is recombinant DNA?

Answer 1

transferring a fragment of DNA from one organism to another

Question 2

How can transferring fragment DNA be passed to different organisms?

Answer 2

The genetic code is universal as well as the transcription and translation being similar allowing proteins to be made

Question 3

What are the name of organisms that contain the transferred DNA?

Answer 3

Transgenic organisms

Question 4

What are the 3 ways DNA fragments can be obtained?

Answer 4

using reverse transcriptase, using restriction endonuclease enzymes and gene machines

Question 5

Explain the process of using reverse transcriptase to obtain DNA fragments

Answer 5

1. Isolating DNA with free RNA nucleotides and reverse transcriptase to produce complementary RNA (cRNA)
2. Then this is used to make a double stranded DNA strand

Question 6

Why is mRNA used in reverse transcriptase to obtain a DNA fragment?

Answer 6

It doesn’t contain introns so it is easier to be used as a template

Question 7

What are the features of a restriction enzymes target site?

Answer 7

• Palindromic (the same forwards as it is backwards)
• specific which means they have a complementary active site to a specific section of a gene
• 4-6 DNA bases

Question 8

Explain simply how restriction enzymes work?

Answer 8

A restriction enzyme is isolated with a DNA base sequence and it will bind to a specific area of a DNA base sequence causing it to cut a fragment. This then leaves a sticky end at on the fragment

Question 9

Why are sticky ends useful?

Answer 9

They can be used to bind (anneal) the DNA fragments to another piece of DNA that has a sticky end with complementary base sequences

Question 10

What is a gene machine?

Answer 10

a database containing necessary information has the ability to produce a DNA sequence from scratch

Question 11

How do gene machines work?

Answer 11

The first is fixed to sme support and in a series of reactions, more DNA bases are added to one another using protecting groups. The protecting product is 20 DNA bases making an oligonucleotide. These can then be joined together to form a longer chain

Question 12

What are protecting groups?

Answer 12

Protecting groups are added to chains to prevent the unwanted branching of the nucleotides

Question 13

What is the difference between in vivo cloning and in vitro cloning?

Answer 13

In vivo takes place inside an organism and in vitro takes place outside an organism

Question 14

Describe the steps involved in the first stage of in vivo amplification - the dna fragment is inserted into a vector

Answer 14

The same restriction endonuclease is used to cut open the vector DNA. This is done so that the sticky ends of the vector DNA and the DNA fragment, are complementary. DNA ligase is used to join the complementary sticky ends of the vector and fragment DNA to one another - ligation. This makes recombinant DNA

Question 15

Describe the second stage of in vivo amplification - the vector transfers the DNA fragment into a host cell

Answer 15

If a plasmid vector is used, host cells have to be persuaded to take in the vector which can be done by chloride ions making the membrane more permeable and then a shock of heat forces the vector into the cell. If it is a bacteriophage, then it will inject its DNA into the host cell and the bacterial DNA will take it up. The host cell is now transformed

Question 16

Describe the third step of in vivo amplification - identifying transformed host cells

Answer 16

When the gene is added to the vector, a marker gene can also be added. When the host cell clones, all cells will contain the cloned genes and marker genes. These marker genes allow only the transformed cells containing the marker gene to survive and grow.

Question 17

Examples of marker genes

Answer 17

Fluorescent and antibiotic resistance

Question 18

What is the PCR?

Answer 18

Polymerase chain reaction is used to make millions of copies of a fragment of DNA in just a few hours

Question 19

What are primers?

Answer 19

primers are a short piece of DNA that is complementary to the bases at the start of the fragment

Question 20

Describe briefly how PCR works

Answer 20

1. Reaction mixture containing the DNA sample, free nucleotides, primers and TAQ polymerase is set up
2. Heated to 95degrees to break H bonds between DNA
3. cooled to 50degrees so primers bind to strands
4. heated to 72degrees so that DNA polymerase can work
5. Free DNA nucleotides bind via complementary base pairing
6. Tow new copies of DNA is formed, one cycle of PCR done
7. mixture starts again with strands now

Question 21

What does anneal mean?

Answer 21

to bind

Question 22

How is using recombinant DNA beneficial in agriculture?

Answer 22

They give higher crop yields, they can gain resistance to pests or weed killers which decreases costs

Question 23

How is recombinant DNA beneficial to industry?

Answer 23

Biological catalysts (enzymes) can be made from transformed organisms and are made in large quantities

Question 24

How is recombinant DNA beneficial in medicine?

Answer 24

Many drugs and vaccines are made from recombinant DNA. These can be made quickly and cheaply and in large quantities

Question 25

What are the negatives of recombinant DNA technology in agriculture?

Answer 25

• Encourages monoculture
• GM plants can interbreed with non GM plants
• Encourages antibiotic resistance in plants

Question 26

What are the negatives of recombinant DNA technology in industry?

Answer 26

• Anti-globalisation activists don’t like globalisation.
• A few large firms own licenses and patents and therefore the may be more able to grow GM plants

Question 27

What are the negatives of recombinant DNA technology in medicine?

Answer 27

Companies who own technologies can limit how much they use it which could be considered unethical

Question 28

What is gene therapy?

Answer 28

the treatment of human diseases

Question 29

How does gene therapy work?

Answer 29

Defective genes inside a cell are altered. For example, if the genes are made up of wo recessive, then one will be altered to become dominant. If one is dominant then a DNA fragment is inserted in between an original DNA

Question 30

What are the two types of gene therapy?

Answer 30

• Somatic therapy
• Germ line therapy

Question 31

What is the difference between somatic and germ line therapy?

Answer 31

Somatic therapy involves altering normal body cells but these have no impact on egg cells. Germ line therapy involves altering egg cells and preventing the inheritance of that disorder

Question 32

What are the benefits of gene therapy?

Answer 32

• No destruction of bone marrow
• No donors are required
• Less chance of rejection because it is own stem cells

Question 33

What are the negatives of gene therapy?

Answer 33

• Faulty red blood cells may still be produced
• Immune response against genetically modified cells