Genetic Modification

Question 1

what is genetic engineering

Answer 1

involves transferring genes from one organism to another

Question 2

what are transgenic organisms

Answer 2

organisms which have received genes from another species

Question 3

what are vectors used for

Answer 3

carrying the DNA from one section to another

Question 4

what is one example of when genetic engineering has been used to treat humans

Answer 4

type 1 diabetes - insulin

Question 5

what do restriction enzymes do

Answer 5

cut DNA at specific sites

Question 6

what do ligase enzymes do

Answer 6

join pieces of DNA together

Question 7

how do restriction enzymes work

Answer 7

they isolate the required gene and leave it with sticky ends (a short section of unpaired bases)

eg the same enzyme then cut a bacterial plasmid and leave it with the same sticky ends

Question 8

how do ligases work

Answer 8

if two pieces of DNA have matching sticky ends ligase will link them to form a single unbroken molecule of DNA

Question 9

what two things can act as vectors for genetic engineering

Answer 9

• plasmids
• viruses

Question 10

how do plasmids and viruses act as vectors for genetic engineering

Answer 10

they take up pieces of DNA then insert this recombinant DNA into other cells

Question 11

what is recombinant DNA

Answer 11

DNA of two different organisms combined as a result of gene transfer

Question 12

for what organisms would you use viruses as the vector for genetic engineering

Answer 12

humans or bacteria

Question 13

for what organisms would you use plasmids as the vector for genetic engineering

Answer 13

for bacteria or yeast

Question 14

what is used to join two separate pieces of DNA together

Answer 14

DNA ligase

Question 15

how does genetic engineering quickly spread

Answer 15

for example insulin

Question 16

how can insulin be produced

Answer 16

the gene for human insulin can be inserted into bacteria which then produce the human insulin, which can be collected and purified for medical use to treat diabetes

Question 17

what are the steps of genetic modification of bacteria to produce human insulin

Answer 17

• the gene for insulin production is located within the chromosome
• restriction enzymes are used to isolate (cut out) the gene, leaving it with sticky ends (short sections of unpaired bases)
• a bacterial plasmid is cut by the same restriction enzyme to leave it with corresponding sticky ends
• the plasmid and human gene are joined together by DNA ligase enzyme
• the genetically engineered plasmid is inserted into the cell
• when the bacterial cell reproduces, the plasmids are copied as well so they can be quickly spread until they all contain the human insulin gene and make human insulin

Question 18

what is a plasmid

Answer 18

a circle of dna inside bacterial cells

Question 19

how can large quantities of insulin be made

Answer 19

put the bacterial cells into a fermenter to control conditions and make them reproduce quickly

Question 20

why are bacteria useful for genetic engineering purposes

Answer 20

• they contain the same genetic code as the organisms we take the genes from so they can easily read it and produce the same proteins
• there are no ethical concerns over their manipulation and growth (unlike animals)
• the plasmids in the bacterial cell separate from the main bacterial chromosome making them easy to remove and manipulate and replace

Question 21

what are genetically modified plants (GM crops - genetically modified crops)

Answer 21

plants that have had foreign DNA inserted into their genome

Question 22

in what ways have some crops been genetically modified already

Answer 22

• to contain a gene from a bacterium that produces a poison that kills insects
• to make them resistant to herbicides
• to produce additional vitamins and improved nutritional value (eg golden rice which contains genes from another plant which make the grain produce a chemical that is turned into vitamin A in the human body)
• to be drought resistant (grow better in dry conditions)

Question 23

advantages of GM crops

Answer 23

• reduced use of chemicals such as herbicides so therefore better for the environment, cheaper and less time consuming for the farmers
• increased yields from the crops as they are not competing with anything

Question 24

what are the disadvantages of GM crops

Answer 24

• increased cost of seeds to cover the cost of developing them = poorer/smaller farms at a disadvantage
• increased dependency on the certain chemicals that the crops are resistant to
• risk of inserted gene being transferred to wild plants by pollination (they could gain the herbicide resistant gene)
• reduced biodiversity
• some researchers say that plants that have had genes inserted into them do not grow as well

Question 25

what is rDNA

Answer 25

recombinant DNA