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Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYBiotechnology: Principles and Processes4 Marks
Question
Explain the methods for making host cell competent to insert the r DNA.
✓

Answer

→ Since DNA is a hydrophilic molecule, it cannot pass through cell membranes.
→ In order to force bacteria to take up the plasmid, the bacterial cells must first be made 'competent' to take up DNA.
Micro-injection :
→ In a method known as micro-injection, recombinant DNA is directly injected into the nucleus of an animal cell.
Biolistics/ Particle bombardment :
→ In another method, suitable for plants, cells are bombarded with high velocity micro- particles of gold or tungsten coated with DNA in a method known as biolistics or gene gun.
Conformational change in the cell wall :
→ This is done by treating them with a specific concentration of a divalent cation, such as calcium, which increases the efficiency with which DNA the bacterium through pores in its cell wall.
→ Recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA on ice, followed by placing them briefly at 42°C (heat shock), and then putting them back on ice.
→ This enables the bacteria to take up the recombinant DNA.

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  1. More resources are allocated to the root during low water conditions.
  2. Competition for water among individuals of a population causes more root growth as compared to individuals who are growing alone.
  3. Lesser leaves are formed under low water conditions.
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  1. Which of the following associations is an example of competitions?
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  2. Balanus and Cathamalus.
  3. Cactus and moth.
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Species and their population (in thousands) in the area
A
B
C
D
E
F
G
H
I
J
I(11)
23
12
0.52
6.0
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1.1
9.0
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II(11)
10.2
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0.62
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3.0
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IV(12)
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4.8
0.4
3.3
0.8
7.3
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2.1
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  2. III
  3. IV
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Species
Species
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I
Mammals
3
II
Birds
2
III
Amphibians
2
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I
Mammals
2
II
Mammals
2
III
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1
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Mammals
3
II
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2
III
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(b)
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(c)
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A
83
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Same
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(d)
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  2. Cohen and Boyer.
  3. Arber and Nathan.
  4. Paul Berg.
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  4. rnRNA will not be formed.
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Image
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