Question
Why is it difficult for DNA to pass through cell membranes? How can E.coli cells be made competent and who developed this method?
✓
Answer
DNA is a hydrophillic molecule so it is difficult to cross lipid molecules of membrane.
- To make E. coli cells competent to take up DNA, they should be treated with divalent cations or calcium.
- In 1970, Mandel and Higa found that E.coli cells become competent to take up DNA when they are suspended in cold calcium chloride.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Identify the figure given alongside.
What is natural selection? How is artificial selection different from natural selection? Give one example each from plants and animals where artificial selection has operated.
Define ectoparasite and endoparasite and give suitable examples.
How biodiversity is important for functional ecosystem?
What is the important of Spirulina as a food?
Cleistogamy can favour only autogamy. Justify
Biodiversity plays a key role in many ecosystem services provided by nature.
(a) Present any two widely useful arguments to prove the validity of the statement.
(b) Write any one moral reason for protecting biodiversity.
(a) Present any two widely useful arguments to prove the validity of the statement.
(b) Write any one moral reason for protecting biodiversity.
- Explain the significance of 'palindromic nucleotide sequence' in the formation of recombinant DNA.
- Write the use of restriction endonuclease in the above process.
Water pollinated (hydrophilous) plants.
Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with any three examples.