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
Which of the following is true regarding cultivation and isolation of animal viruses? View Available Hint(s) Which of the follow
Studentka2010 [4]

completed question'

.....culturing viruses that requires a human host

Answer:

Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host

Explanation

Viruses can not thrive in a non-living host or artificial media.They  are intracelular parasites  which needed living host to replicate . Cultures lines from Human embryo  in are therefore used for culturing viruses of human host, so that its mode of replication and gene expression can be studied, and therefore its virulence can easily be studied.

This method have the advantage that;

1.there is no need to make use of the whole animal rather,on a tiny tissue needed can be isolated for culture.

2. the cells growth is continuous,and can be preserved in liquid Nitrogen and renew for future culture

3. cells can be grown in different containers,  with ability to decide the number of cells needed.

Temperature is kept at optimum for human in the culture at  37 degree centigrade, nutrients are provided, NaHC03 as buffers for C02, and  the medium is humidified.

3 0
3 years ago
Species with homologous structures most likely:
nikitadnepr [17]

Species with more likely homologous structures share a common ancestor.

  • D. share a common ancestor.

<h3>What are example homologous structures?</h3>

The most correct definition for homology would be: They are structures of individuals, of different species or not, that were inherited from a common ancestor. The human arm is homologous to the horse's front leg. The bat's wing is homologous to the whale fin.

With this information, we can conclude that homologous  have same embryological origin of structures from different organisms, and these structures may or may not have the same function

Learn more about homologous structures in brainly.com/question/7904813

#SPJ1

7 0
1 year ago
Read 2 more answers
MMMMMM! Dinner's cooking. Soon we'll be eating some chicken and dumplings. Our digestive system will get to work on the food we
xxMikexx [17]
I think the answer is D. Circulatory  because this system helps to get the absorbed nutrients throughout the whole body
5 0
3 years ago
Read 2 more answers
Please answer the best you can.
Zina [86]
Telophase 2 is the last phase of Meiosis !!

so it consists of
3) spindle fibre starts to disappear
4) Nuclear membrane forms
5) late telophase show cytokinesis !!

so 3,4 and 5 are your answers !!
3 0
3 years ago
I need help with cell types gizmo<br>​
Georgia [21]

Explore a wide variety of cells, from bacteria to human neurons, using a compound light microscope. Select a sample to study, then focus on the sample using the coarse and fine focus controls of the microscope. Compare the structures found in different cells, then perform tests to see if the sample is alive.

8 0
2 years ago
Other questions:
  • Pea contains only 0.25% phenylethyl alcohol because high concentrations inhibit both gram-positive and gram-negative organisms.
    11·1 answer
  • Which of the following statements is true?
    6·2 answers
  • Pls help!!
    9·2 answers
  • The trait for Huntington's disease in humans shows a dominant pattern of inheritance. The alleles for Huntington's disease in tw
    10·2 answers
  • Which group of moths is better adapted to survive the hunting cycle
    15·2 answers
  • Write the difference
    6·1 answer
  • Summarize the role of meiosis in the human life cycle vs the role of mitosis.
    5·1 answer
  • Read the passage below and use the information to answer the question that follows. Joey is the oldest of three children. Like h
    12·2 answers
  • Fill in the blanks:
    8·1 answer
  • IS a catfish a producer, consumer, or decomposer?
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!