21.4 Genetic Engineering

Question 1

What is genetic engineering?

Answer 1

The manipulation of the genome

Question 2

What is the basic principal of genetic engineering?

Answer 2

Isolating a gene for a desired characteristic in one organism, and placing it in another organism, using a suitable vector

Question 3

What is a transgenic organism?

Answer 3

An organism that carries a gene from another organism

Question 4

What is the main technique for isolating a desired gene?

Involves enzymes

Answer 4

• Restriction endonucleases cut the required gene from the DNA
• Each endonuclease is restricted to specific base sequences in the molecule

Question 5

What is the benefit of restriction endonucleases forming “sticky ends”?

Answer 5

Makes it easier to insert the desired gene into other DNA

Question 6

What is used to cut the desired gene out of DNA?

Answer 6

Restriction endonucleases (enzymes)

Question 7

What is another technique for isolating a gene using mRNA?

Answer 7

mRNA for the desired gene is isolated, and reverse transcriptase produces a single strand of complementary DNA

Question 8

What vector is most commonly used to insert the DNA into a host cell?

Answer 8

Bacterial plasmids

Question 9

What happens once the vector plasmid enters a host cell?

Answer 9

It can combine with the host DNA to form recombinant DNA

Question 10

What is recombinant DNA?

Answer 10

DNA from 2 sources

Question 11

What is a marker gene?

Answer 11

A gene inserted alongside the target gene to identify cells that have taken up the plasmid

Question 12

How do you insert DNA into a plasmid?

Answer 12

• Cut plasmid open with same restriction endonuclease
• DNA ligase forms phosphodiester bonds between the sugar and phosphate groups on the 2 strands of DNA, joining them together

Question 13

What are the two methods of transferring the vector into host cells?

Answer 13

• Culturing bacterial cells in a calcium-rich solution and increasing the temperature
• Electroporation

Question 14

What is electrofusion?

Answer 14

Tiny electrical currents are applied to the membranes of two different cells, fusing their nuclear membranes to form a hybrid/polypoid cell

Question 14

What happens during electroporation?

Answer 14

Small electrical current applied to the bacteria. Makes the membrane porous, so the plasmids move into the cells

Question 15

Why are the bacteria cells cultured in a calcium-rich solution at increased temperatures?

Answer 15

Makes the bacterial membrane permeable, allowing plasmids to enter

Question 16

Why does the electrical current during electroporation have to be carefully controlled?

Answer 16

Or else the membrane is permanently damaged, destroying the whole cell

Question 17

What is a key process that electrofusion is used for?

Answer 17

Formation of MABs

Question 18

Why is it harder to engineer the DNA of animal cells?

Answer 18

Because animal cell membranes are less easier to manipulate

Question 19

How is a plant cell genetically modified?

Answer 19

• Insert bacteria with desired gene in plasmid into plant cells
• Transgenic plant cells form a callus. Each one can be used to grow a new transgenic plant
• Or can be produced through electrofusion