1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Doss [256]
3 years ago
14

A DNA fragment is introduced into the lacZ gene of a plasmid, which also contains an ampicillin resistance gene. What is the app

earance of bacteria transformed with this plasmid if they are spread on plates containing ampicillin and Xgal?

Biology
1 answer:
zhenek [66]3 years ago
8 0

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

You might be interested in
3419059779 pppppppppppppppppppppppppppppppppppp1234​
Elena L [17]

Answer:

99192883829299]pppppppp??

8 0
3 years ago
The ability of your body's immune system to distinguish between your cells
KatRina [158]

Answer:

<em>The correct option is cell surface markers.</em>

Explanation:

The immune cells of our body detect foreign particles and generate responses so that our body can get rid of them. The foreign particles are often termed as antigens.

The immune cells such as antibodies possess cell surface receptors which detect the foreign objects or antigens. When the cell surface receptors detect any antigen they immediately recognize that a foreign particle has invaded the body and they then identify it and start to generate response.

6 0
3 years ago
Primary consumers depend on energy from plants for survival. Higher consumers depend on energy from primary consumers for surviv
yaroslaw [1]
The answer is C
The more plants there are, the more consumers there are. If there aren't enough plants, the consumers have no way of getting energy, and therefore cannot survive. The species also matters, because certain species of plants can only be eaten by certain species of consumers.
4 0
3 years ago
Which of the following is not correct about diffraction?
kotykmax [81]

Answer:

Diffraction occurs just with electromagnetic waves.

Explanation:

8 0
3 years ago
How do nurse researchers strive for constancy of conditions in implementing a treatment?
zhenek [66]
<span>Having standard written research protocols is the correct answer. ;)</span>
4 0
3 years ago
Other questions:
  • One of the central themes in biology is how DNA, RNA, and proteins are related. Describe how genetic information flows between t
    15·1 answer
  • A mutation is made once in every _ nucleotides copied
    14·2 answers
  • Whole sheet? Use this <br> 30pts
    9·2 answers
  • What is the rule of a control group in any experiment
    9·1 answer
  • Electricity falls into what class of energy (A)Chemical because of the reactions taking place
    8·1 answer
  • Complete the following sentences.
    11·2 answers
  • What are the characteristics of prokaryotes? 1. A prokaryote lacks a well-defined nucleus. 2. A prokaryote cannot perform basic
    8·1 answer
  • what are large chemical compounds, primarily consisting of carbon and hydrogen, that exist in living organisms.
    14·1 answer
  • Explain how at least three pieces of evidence support the theory of evolution
    10·1 answer
  • 26. Northern Harrier Hawks, also known as Marsh Hawks, get their name from their hunting
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!