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
A plant that has two identical alleles at the same gene locus is said to be ______.
DerKrebs [107]
A is the correct answer
5 0
3 years ago
The heart is composed of 2 pumps. the right side pumps blood to ________ and the left side pumps blood to ______.
liraira [26]
Oxygen
Carbon dioxide
4 0
3 years ago
Characteristics that are always present in living organisms are ​
ra1l [238]

Answer:

yes it is movement

Explanation:

it is movement

3 0
3 years ago
Read 2 more answers
Help pls!!!<br><br> Describe two ways to reduce air pollution and slow climate change.
Pepsi [2]
Plant trees because they absorbe co2
8 0
3 years ago
Read 2 more answers
Cisplatin an antitumor drug interact with DNA____________
Strike441 [17]

Answer:

B

Explanation:

An alkylating agent adds an alkyl group to the DNA strand of a specific cell group highly prone to being cancerous. This action is exactly what Cisplatin does by disrupting DNA replication (mitosis) for cancerous cells by inserting itself into a DNA strand.

4 0
3 years ago
Read 2 more answers
Other questions:
  • Why do earthquakes often cause damaging fires
    11·2 answers
  • homeo- comes from a greek word means still the suffix stasis comes from "stoppage" or "standstill" how does this relate to homeo
    12·1 answer
  • Beginning with carbon fixation, arrange the steps of the Calvin cycle in the correct order.
    11·2 answers
  • What unit of measurement is most appropriate for measuring the size of atoms?
    5·1 answer
  • What is 3.5% of 11? Round to the nearest hundredth
    6·2 answers
  • 3 mutations frameshift mutation how im going to remeber this meaning answer
    9·1 answer
  • After completing 10 years of experimentation, a scientist reports a
    15·1 answer
  • How does a dog meet all the characteristics of life
    14·1 answer
  • 2. Explain the movement of initial energy from the sun<br> through an energy pyramid.
    12·1 answer
  • The classification of organisms is called (1 point)
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!