exam questions

Question 1

describe how an isolated human insulin gene is inserted into a bacteria plasmid (4)

Answer 1

• restriction endonucleases -cut open DNA at recognition site
• forming sticky ends
• same enzymes cuts open plasmid
• forms complementary sticky ends which bind to DNA
• DNA ligase joins gaps

Question 2

suggest two ways that bacteria which take up modified plasmids can be identified (2)

Answer 2

• fluorescent dye: glowing bacteria have plasmid
• antibiotic resistant genes: survivors have plasmid

Question 3

suggest why it is preferable to use genetically engineered sources of human insulin rather than insulin obtained from pigs (2)

Answer 3

• no religious objections
• cheaper
• more efficient

Question 4

suggest one ethical objection to the use of stem cells from human embryos (1)

Answer 4

• form of abortion
• kills a potential human

Question 5

explain what is meant by restriction enzyme (3)

Answer 5

• enzyme which cuts through DNA
• at a specific site called a recognition site
• forming sticky ends

Question 6

outline the formation of recombinant DNA (4)

Answer 6

• restriction endonucleases cut through DNA and forms sticky ends
• same enzyme cuts plasmid to form complementary sticky ends
• bind with hydrogen bonding
• ligase joins gaps in backbone

Question 7

explain what is meant by recombinant DNA (1)

Answer 7

2 sources of DNA joined together

Question 8

describe how genetic engineering has been used to produce human insulin (3)

Answer 8

• DNA is isolated using restriction enzymes
• plasmid bacteria is cut open using same enzymes
• forms complementary sticky ends
• gene is inserted into plasmid - forms H bonds
• ligase joins gaps in backbone

Question 9

what are the advantages of using genetic engineering to produce human insulin (3)

Answer 9

• rapid process
• body won’t reject
• reliable supply

Question 10

describe the role of restriction enzymes in genetic engineering (3)

Answer 10

• cut DNA at recognition sites
• cut plasmid
• form complementary sticky ends

Question 11

describe the role of ligase in genetic engineering (2)

Answer 11

• joins sticky ends of DNA and plasmid
• seals DNA backbone

Question 12

describe the role of DNA polymerase in genetic engineering (2)

Answer 12

forms double strand, used in PCR

Question 13

explain the role of a promoter in genetic engineering (2)

Answer 13

turns on transcription & binds RNA polymerase

Question 14

discuss benefits and problems with using gene therapy in treatment of diabetes rather than taking insulin (4)

Answer 14

benefits
- avoids injections
- less restriction on lifestyle

problems
- takes a long time to have effects
- rejection

Question 15

suggest why humans have more DNA than bacteria (2)

Answer 15

• humans are eukaryotes
• so have larger proteins
• bacteria are much smaller

Question 16

which enzyme removes the gene from the genome (1)

Answer 16

restriction endonuclease