MOLECULAR BIOLOGY EXAM 1
QUESTIONS AND ANSWERS 100%
CORRECT
The process of ------ in eukaryotic cells is analogous to bacterial transformation.
a. Transfection
b. Transcription
c. Transition
d. Translation
e. Translocation - ANSWER-A. Transfection
Hersehy and Chase tracked DNA during phage infection using a radioisotope of:
a. oxygen
b. sulfur
c. nitrogen
d. phosphorus
e. carbon - ANSWER-d. phosphorus
Mutations that have no apparent effect are called:
a. silent mutations
b. loss-of-function mutations
c. null mutations
d. leaky mutations
e. gain-of-function mutations - ANSWER-a. silent mutations
If the mole % of A residues in double-stranded DNA is 29%, what would the mole % of
G residues be? - ANSWER-21%
Meselson and Stahl used density labeling of DNA to show that DNA replication occurs
via a semiconservative mechanism. If DNA is isolated and separated by density, how
many bands would be observed and how would their density compare with the starting
DNA? The DNA would yield two different density bands. - ANSWER-Two of the
daughters would contain one original heavy parental strand and one light daughter
strand (hybrid density), and two of the daughters would contain two light strands (light
density)
G-C content of one of them is 32% and the G-C content of the other is 62%. One of the
organisms lived deep in the ocean at temperatures around 10 C and the other was
isolated from the mojave desert, where temps reached 45 C - ANSWER-Mojave desert
, is likely to have a G-C content of 62% and the ocean bacteria is likely to have a G-C
content of 32%. Organisms that thrive at elevated temperatures have genomes with a
higher fraction of G-C base pairs to stabilize the double helical structure of their DNA
Define a molecular probe and describe its use to identify a specific nucleic acid
sequence - ANSWER-A probe is a single-stranded polynucleotide (DNA or RNA) that
has a radiolabel or fluorescent label. It must be complementary to the (single-stranded)
target sequence of interest so that it will hybridize to the target, and thus the presence
of the target will be revealed by the label
Describe the technique of in situ hybridization and its purpose - ANSWER-allows detect
of a specific sequence at a specific location in an intact cell or tissue
Compare the purpose of gene knockouts, knock-ins, and knockdowns - ANSWER-Gene
knockout- used to "delete" a gene by frameshift insertion
Gene knock-in- replacing a gene with an alternate version of the same gene
Gene knockdowns- do not alter the product of the gene, but rather decrease its level of
expression
What is the advantage of the use of a DNA microarray over Southern blotting/ probe
hybridization - ANSWER-DNA microarray, can contain hundreds of thousands of DNA
fragments that can be simultaneously hybridized
Which of the following sequences is inversely palindromic?
a. 5' GCATGC 3'
b. 5' GCAACG 3'
c. 5' GCAT 3'
d. 5' GCAACGC 3'
e. 5' GGAAAAGG 3' - ANSWER-a. 5' GCATGC 3'
Which of the following is not a good feature of a plasmid vector?
a. multiple cloning site
b. telomeres
c. antibiotic resistance gene
d. origin of replication
e. blue/white selection system - ANSWER-b. telomeres
during meiosis, genes that are on opposite ends of a long eukaryotic chromosome:
a. never recombine
b. show less than 50% recombination
c. show exactly 50% recombination
d. show between 50% and 100% recombination
e. show 100% recombination - ANSWER-c. show exactly 50% recombination
QUESTIONS AND ANSWERS 100%
CORRECT
The process of ------ in eukaryotic cells is analogous to bacterial transformation.
a. Transfection
b. Transcription
c. Transition
d. Translation
e. Translocation - ANSWER-A. Transfection
Hersehy and Chase tracked DNA during phage infection using a radioisotope of:
a. oxygen
b. sulfur
c. nitrogen
d. phosphorus
e. carbon - ANSWER-d. phosphorus
Mutations that have no apparent effect are called:
a. silent mutations
b. loss-of-function mutations
c. null mutations
d. leaky mutations
e. gain-of-function mutations - ANSWER-a. silent mutations
If the mole % of A residues in double-stranded DNA is 29%, what would the mole % of
G residues be? - ANSWER-21%
Meselson and Stahl used density labeling of DNA to show that DNA replication occurs
via a semiconservative mechanism. If DNA is isolated and separated by density, how
many bands would be observed and how would their density compare with the starting
DNA? The DNA would yield two different density bands. - ANSWER-Two of the
daughters would contain one original heavy parental strand and one light daughter
strand (hybrid density), and two of the daughters would contain two light strands (light
density)
G-C content of one of them is 32% and the G-C content of the other is 62%. One of the
organisms lived deep in the ocean at temperatures around 10 C and the other was
isolated from the mojave desert, where temps reached 45 C - ANSWER-Mojave desert
, is likely to have a G-C content of 62% and the ocean bacteria is likely to have a G-C
content of 32%. Organisms that thrive at elevated temperatures have genomes with a
higher fraction of G-C base pairs to stabilize the double helical structure of their DNA
Define a molecular probe and describe its use to identify a specific nucleic acid
sequence - ANSWER-A probe is a single-stranded polynucleotide (DNA or RNA) that
has a radiolabel or fluorescent label. It must be complementary to the (single-stranded)
target sequence of interest so that it will hybridize to the target, and thus the presence
of the target will be revealed by the label
Describe the technique of in situ hybridization and its purpose - ANSWER-allows detect
of a specific sequence at a specific location in an intact cell or tissue
Compare the purpose of gene knockouts, knock-ins, and knockdowns - ANSWER-Gene
knockout- used to "delete" a gene by frameshift insertion
Gene knock-in- replacing a gene with an alternate version of the same gene
Gene knockdowns- do not alter the product of the gene, but rather decrease its level of
expression
What is the advantage of the use of a DNA microarray over Southern blotting/ probe
hybridization - ANSWER-DNA microarray, can contain hundreds of thousands of DNA
fragments that can be simultaneously hybridized
Which of the following sequences is inversely palindromic?
a. 5' GCATGC 3'
b. 5' GCAACG 3'
c. 5' GCAT 3'
d. 5' GCAACGC 3'
e. 5' GGAAAAGG 3' - ANSWER-a. 5' GCATGC 3'
Which of the following is not a good feature of a plasmid vector?
a. multiple cloning site
b. telomeres
c. antibiotic resistance gene
d. origin of replication
e. blue/white selection system - ANSWER-b. telomeres
during meiosis, genes that are on opposite ends of a long eukaryotic chromosome:
a. never recombine
b. show less than 50% recombination
c. show exactly 50% recombination
d. show between 50% and 100% recombination
e. show 100% recombination - ANSWER-c. show exactly 50% recombination
