Question
Write any four ways used to introduce a desired DNA segment into a bacterial cell in recombinant technology experiments.
✓
Answer
Four-ways of introducing the desired DNA segment into a bacterial cell are as follows:
i. Competent host (For transformation with recombinant DNA):
a. For transformation, bacterial cells are treated with a specific concentration of calcium which increases the efficiency with which DNA enters the bacterium through pores in its cell wall.
b. Cells with recombinant DNA are incubated on ice, followed by placing them briefly at 42°C (heat shock) and then putting them back into ice.
This enables the bacteria to take up recombinant DNA.
ii. Micro-injection: Recombinant DNA is directly injected into the nucleus of an animal cell.
iii. Biolistic or Gene gun: Plant cells are bombarded with high-velocity micro-particles of gold or tungsten coated with DNA.
iv. "Disarmed pathogen"vectors: (Ti- plasmid); retroviruses which when allowed to infect the cell, transfer the recombinant DNA into the host.
i. Competent host (For transformation with recombinant DNA):
a. For transformation, bacterial cells are treated with a specific concentration of calcium which increases the efficiency with which DNA enters the bacterium through pores in its cell wall.
b. Cells with recombinant DNA are incubated on ice, followed by placing them briefly at 42°C (heat shock) and then putting them back into ice.
This enables the bacteria to take up recombinant DNA.
ii. Micro-injection: Recombinant DNA is directly injected into the nucleus of an animal cell.
iii. Biolistic or Gene gun: Plant cells are bombarded with high-velocity micro-particles of gold or tungsten coated with DNA.
iv. "Disarmed pathogen"vectors: (Ti- plasmid); retroviruses which when allowed to infect the cell, transfer the recombinant DNA into the host.
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|
Disease
|
Casual organisms
|
Medium of transfer
|
Symptoms
|
|
Amoebiasis
|
Entamoeba histolytica
|
a
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Diarrhoea
|
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Typhoid
|
b
|
Contaminated food
|
Sustained high fever
|
|
c
|
Plasmodium
|
Bite of infected female Anopheles mosquito
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Chill and high fever
|
|
Pneumonia
|
Steptococcus
|
d
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|