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ELEN [110]
3 years ago
15

Which of the following substances is a weak base? .... lemon juice , vinegar , sea water , or pure water

Biology
1 answer:
larisa [96]3 years ago
8 0
Pure water is your answer
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A DNA fragment is introduced into the lacZ gene of a plasmid, which also contains an ampicillin resistance gene. What is the app
zhenek [66]

Answer: The bacteria transformed with this particular plasmid will form white colonies on the plates containing ampicillin and Xgal.

Explanation: The lacZ gene produces an enzyme called β-galactosidase which is responsible for the breakdown of lactose into glucose and galactose. The lacZ gene is one of the three genes (the other two being lacA and lacY) of the lac operon which is responsible for the transport and mechanism of lactose in E. coli and many other bacteria.

In recombinant DNA technology, when a plasmid is to be used to transform a host cell, such markers are used to help screen the transformed cells from the ones that have not taken up the plasmid. Xgal present in the plates is an artificial substrate which is hydrolyzed by

β-galactosidase into 5-bromo-4-chloro-indoxyl which will dimerize and oxidise into 5,5'-dibromo-4,4'dichloro-indigo. This is a blue pigment which will give blue color to the bacterial cells. Introducing a DNA fragment in this lacZ gene will make it non-functional so it will not be able to produce the enzyme.

Therefore, when a bacterial cell is transformed with a plasmid containing ampicillin resistance gene and a DNA fragment introduced in the lacZ gene and then grown on plates containing ampicillin and Xgal, white colored colonies will appear. The white colonies will show the bacterial cells that have successfully taken up the plasmid with the DNA fragment incorporated in the lacZ gene as this will render the gene non-functional and will not produce β-galactosidase which will breakdown Xgal to give blue colonies. Since the plates contain ampicillin, only the bacterial cells that have been successfully transformed with the plasmid ( the ones that have the DNA fragment and the ones without it) will grow as the ampicillin resistance will give them resistance against ampicillin in the plates. The bacterial cells that have not taken up the plasmid will not be resistant to ampicillin and will not form colonies on the plate.

This is called blue-white screening which is used to identify successfully transformed host cells. A picture of this is given in the attachment, taken from the following website:

https://www.mun.ca/biology/scarr/Blue_&_White_Colonies.html

8 0
3 years ago
Which of the following is an example of gene splicing? A. a mutation that occurs during meiosis results in a chromosomal abnorma
krok68 [10]
A. The mutation that occurs during meiosis is a sure way of gene splitting I presume:)
6 0
3 years ago
What sort of evidence can you use to show that all living things grow and develop
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A common human, they go from an embryo then develop into an infant then grow to a teen. once a teen they might go through changes...
a plant is also evidence, they develope from a seed to a small bud and grow to a small plant.
7 0
3 years ago
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Which of these statements expresses a scientific theory?
alexgriva [62]

Answer: The cell is the basic structural and functional unit of living organisms

Explanation:

3 0
3 years ago
The purpose of a business continuity planning session in an organization is to ________.
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I believe that the purpose of business continuity planing session in an organization is to discuss how to return the organization to normal operations as quickly as possible after a data breach. Business continuity planning is the creation of a strategy through the recognition of threats and risks facing a company, with an aim of ensuring that personnel and assets are protected and in a position to function in the event of a disaster.
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