Biochemistry 4th Edition by Donald
Voet - Test Bank
You are attempting to clone a 250-kb segment of mouse DNA in a
yeast artificial chromosome. You obtain 5000 similar-sized clones
representing the entire mouse genome. How confident are you that
you have cloned the DNA you are interested in? - ---ASNWERS----
Use Equation 3-1 to calculate P, given N = 5000 and f = 250
kb/2,500,000 kb = 10^4.
P = 1 - (1-f)^N
P = 1 - (1 - 10^-4)^5000
P = 0.39
The probability that you have cloned the desired DNA segment is
less than 40%.
Why is a genomic library larger than a cDNA library for a given
organism? - ---ASNWERS----The genomic library contains DNA
sequences corresponding to all the organism's DNA, which includes
genes and non-transcribed sequences. A cDNA library represents
only the DNA sequences that are transcribed into mRNA.
Why do cDNA libraries derived from different cell types within the
same organism differ from each other? - ---ASNWERS----Different
, cell types express different sets of genes. Therefore, the populations
of mRNA molecules used to construct the cDNA libraries also differ.
Describe the possible outcome of a PCR experiment in which (a) one
of the primers is inadvertently omitted from the reaction mixture
and (b) one of the primers is complementary to several sites in the
starting DNA sample. - ---ASNWERS----(a) Only single DNA
strands of variable length extending from the remaining primer
would be obtained. The number of these strands would increase
linearly with the number of cycles rather than geometrically.
(b) PCR would yield a mixture of DNA segments whose lengths
correspond to the distance between the position of the primer with a
single binding site and the various sites where the multispecific
primer binds.
A diploid organism with a 45,000-kb haploid genome contains 21%
G residues. Calculate the number of A, C, G, and T residues in the
DNA of each cell in this organism. - ---ASNWERS----Since the
haploid genome contains 21% G, it must contain 21% C (because G
C) and 58% A T (or 29% A and 29% T, because A T). Each cell is
diploid, containing 90,000 kb or 9*10^7 bases. Therefore,
A = T = (0.29) (9*10^7) = 2.61*10^7 bases
A = T = (0.21) (9*10^7) = 1.89*10^7 bases
A segment of DNA containing 20 base pairs includes 7 guanine
residues. How many adenine residues are in the segment? How
many uracil residues are in the segment? - ---ASNWERS----The
DNA contains 40 bases in all. Since G C, there are 7 cyto sine
residues. The remainder (40 14 26) must be adenine and thymine.
Voet - Test Bank
You are attempting to clone a 250-kb segment of mouse DNA in a
yeast artificial chromosome. You obtain 5000 similar-sized clones
representing the entire mouse genome. How confident are you that
you have cloned the DNA you are interested in? - ---ASNWERS----
Use Equation 3-1 to calculate P, given N = 5000 and f = 250
kb/2,500,000 kb = 10^4.
P = 1 - (1-f)^N
P = 1 - (1 - 10^-4)^5000
P = 0.39
The probability that you have cloned the desired DNA segment is
less than 40%.
Why is a genomic library larger than a cDNA library for a given
organism? - ---ASNWERS----The genomic library contains DNA
sequences corresponding to all the organism's DNA, which includes
genes and non-transcribed sequences. A cDNA library represents
only the DNA sequences that are transcribed into mRNA.
Why do cDNA libraries derived from different cell types within the
same organism differ from each other? - ---ASNWERS----Different
, cell types express different sets of genes. Therefore, the populations
of mRNA molecules used to construct the cDNA libraries also differ.
Describe the possible outcome of a PCR experiment in which (a) one
of the primers is inadvertently omitted from the reaction mixture
and (b) one of the primers is complementary to several sites in the
starting DNA sample. - ---ASNWERS----(a) Only single DNA
strands of variable length extending from the remaining primer
would be obtained. The number of these strands would increase
linearly with the number of cycles rather than geometrically.
(b) PCR would yield a mixture of DNA segments whose lengths
correspond to the distance between the position of the primer with a
single binding site and the various sites where the multispecific
primer binds.
A diploid organism with a 45,000-kb haploid genome contains 21%
G residues. Calculate the number of A, C, G, and T residues in the
DNA of each cell in this organism. - ---ASNWERS----Since the
haploid genome contains 21% G, it must contain 21% C (because G
C) and 58% A T (or 29% A and 29% T, because A T). Each cell is
diploid, containing 90,000 kb or 9*10^7 bases. Therefore,
A = T = (0.29) (9*10^7) = 2.61*10^7 bases
A = T = (0.21) (9*10^7) = 1.89*10^7 bases
A segment of DNA containing 20 base pairs includes 7 guanine
residues. How many adenine residues are in the segment? How
many uracil residues are in the segment? - ---ASNWERS----The
DNA contains 40 bases in all. Since G C, there are 7 cyto sine
residues. The remainder (40 14 26) must be adenine and thymine.
