4.2

Question 1

Genetic engineering is a

Answer 1

collection of techniques by which genes are altered or transferred from one organism to another

Question 2

The modified DNA is called:

Answer 2

recombinant DNA

Question 3

GE involves 3 things:

Answer 3

o Obtaining or isolating the gene to be transferred
o Transferring the gene into the new cells
o Identifying the modified cells

Question 4

A useful application of GE is the production of human insulin to treat

Answer 4

Type 1 diabetes

Question 5

Before GE, insulin from pigs was used. This differs from human insulin by only 1 amino acid - sometimes causes an

Answer 5

immune response in diabetics

Question 6

the gene for human insulin can be inserted into bacterial cells and the bacteria are

Answer 6

grown in large numbers and the insulin is extracted

Question 7

As human insulin is now used, which is identical in every person, diabetics are unlikely to show an

Answer 7

immune response

Question 8

Gene for human insulin needs to be obtained - 3 ways to do this:

Answer 8

1-Gene may be CUT OUT of human DNA
2-Gene may be made from mRNA
3- Using DNA bases sequence that codes for human insulin and then making multiple copies (PCR)

Question 9

1- Cutting out of DNA, 2 stages:

Answer 9

1-Human insulin gene located using a gene probe

2-DNA is cut out using a restriction enzyme

Question 10

Gene probes are:

Answer 10

specific segment of single-strand DNA that is complementary to a desired gene

Question 11

Restriction enzymes are:

Answer 11

an enzyme that cuts DNA molecules at a specific sequence of bases called a recognition sequence
-leaving sticky ends

Question 12

2-Gene may be made from mRNA, e.g. the cells in the pancreas that produce insulin have a large amount of mRNA coding for insulin - this mRNA can be isolated
, 4 steps:

Answer 12

1-Reverse transcriptase is used to make a DNA copy from its RNA
2-Genetic engineers use reverse transcriptase to make a single-stranded DNA copy of the mRNA from the pancreas cells
3-This single-stranded DNA is called cDNA (‘copy DNA’)
4-The cDNA is then made into double-stranded DNA

Question 13

3-Using DNA bases sequence that codes for human insulin and then making multiple copies (PCR)

Answer 13

• 3 bases code for 1 amino acid
• work out DNA base sequence that codes for human insulin
• use DNA base sequence to synthesise more copies

Question 14

What is used to transfer the isolated gene into a new host cell?

Answer 14

vector

Question 15

Most common type of vector =

Answer 15

plasmid

Question 16

(INSERTING THE DNA INTO NEW CELLS)

Step 1: DNA in the plasmid is cut open using a

Answer 16

restriction enzyme

Question 17

the restriction enzyme used in step 1 is often the same one used to isolate the new gene, if not, nucleotides are added to the cut plasmid and to the isolated gene so that they have

Answer 17

matching sticky ends

Question 18

(INSERTING THE DNA INTO NEW CELLS)

Step 2: the gene is then inserted into the cut plasmid using the enzyme

Answer 18

DNA ligase

Question 19

(INSERTING THE DNA INTO NEW CELLS)

Step 3: the bacterial cells and plasmids are

Answer 19

mixed together

Question 20

(INSERTING THE DNA INTO NEW CELLS)

Step 4: the bacteria are treated so that many of them take up a

Answer 20

modified plasmid or recombinant plasmid

Question 21

(USING GENETIC MARKERS)

Some of the bacterial cells do not take up a plasmid, or take up a

Answer 21

non-recombinant plasmid

Question 22

(USING GENETIC MARKERS)
It is not possible to tell by looking at the cells which one contain the insulin gene, however, the plasmid used contain an

Answer 22

antibiotic resistance gene

Question 23

(USING GENETIC MARKERS)

The antibiotic resistance gene gives resistance to a specific antibiotic, such as tetracycline, and is called a

Answer 23

genetic marker

Question 24

(USING GENETIC MARKERS)
The scientists can mix the bacteria with the antibiotic that the marker gene gives resistance to, this will kill all the bacteria that do not contain a

Answer 24

plasmid

Question 25

(USING GENETIC MARKERS)

Marker genes may also code for

Answer 25

other characteristics that are easy to identify, such as production of a fluorescent protein or a specific enzyme

Question 26

What enzyme makes a single-stranded piece of DNA using an RNA template?

Answer 26

Reverse transcriptase

Question 27

What enzyme joins 2 pieces of DNA together?

Answer 27

DNA ligase

Question 28

What enzyme cuts DNA whenever it recognises a specific base sequence?

Answer 28

Restriction enzyme