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
Answer:
when the pores are completely filled in the rocks and soil
Explanation:
The zone of saturation is part of the divisions of ground water systems. It is the zone in which the pore spaces within the rock are completely filled with water.
The zone of saturation is where the aquifer lies in a body of water and it is the ground water prospect. Pore spaces can also be filled with hydrocarbons.
Above the zone of saturation is the water table. The water table defines the upper layer of the zone of saturation above which the pore spaces are filled with gas or no water can be found.
The log will float on the water because his density is lower than the liquid, so it will stay at the top due to Archimedes' principle.
<span>Archimedes' principle is a physical law that describes the upward force (the vertical thrust) experienced by any body immersed in a fluid (liquid or gas). This force is strongly related to the density of both the fluid and the body.
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You can try the experience at home, by using an object that has a lower density than the water like the sunflower oil, you will see that it will stay at the top of the water too.
Answer:A plane's engines are designed to move it forward at high speed. That makes air flow rapidly over the wings, which throw the air down toward the ground, generating an upward force called lift that overcomes the plane's weight and holds it in the sky. ... The wings force the air downward and that pushes the plane upward.