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#Question id: 53

Calculate the number of times the DNA of a modern E. coli cell has been copied accurately since its earliest bacterial precursor cell arose about 3.5 billion years ago. Assume for simplicity that over this time period, E. coli has undergone, on average, one cell division every 12 hours (this is an overestimate for modern bacteria, but probably an underestimate for ancient bacteria).

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. 4.6 × 10^12 generations

  2. 3.4 × 10^13 generations

  3. 2.6 × 10^12 generations

  4. 2.6 × 10^11 generations

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TLS Online TPP Program

#Question id: 18956

#Unit 13. Methods in Biology

It is possible to calculate the number of clones that must be present in a gene library to give a probability of obtaining a particular DNA sequence. This formula is:
 
where N is the number of recombinants, P is the probability and f is the fraction of the genome in one insert. Thus for the E. coli DNA chromosome of 5 × 10 6 bp andan insert size of 20 kb ( f = 0.004), the number of clones needed ( N ) would be 1 × 10 3 ,with a probability of P will be
TLS Online TPP Program

#Question id: 18957

#Unit 13. Methods in Biology

A DNA fragment of 5000bp needs to be isolated from E.coli (genome size 4x103kb) genomic library. The minimum number of independent recombinant clones required to represent this fragment in genomic library are
TLS Online TPP Program

#Question id: 18958

#Unit 13. Methods in Biology

The number of clones to represent this fragment in genomic library with a probability of 95% are
TLS Online TPP Program

#Question id: 18959

#Unit 13. Methods in Biology

 Vectors used for construction of genomic libraries, and their capacity is given match them correctly
A- λ EMBL series                                                                                   I - 300kb - 1,400 kb
B - Cosmids                                                                                                 II - 45 kb
C – BACs and YACs (high capacity vectors)                                             III - 20kb
TLS Online TPP Program

#Question id: 18960

#Unit 13. Methods in Biology

cDNA library do not require very large vectors hence which of the following is commonly used in cDNA library
TLS Online TPP Program

#Question id: 18961

#Unit 13. Methods in Biology

When a cDNA library is generated by first removing those mRNA or cDNA sequences that are common to two sources, e.g., two different Cell types, such a library is called