BIO 107 EXAM II QUESTIONS AND
ANSWERS
Suppose you are provided with an actively dividing culture of E. coli bacteria to which
radioactive thymine has been added. What would happen if a cell replicates once in the
presence of this radioactive base? - Correct Answers -DNA in both daughter cells would
be radioactive
Put the following steps of DNA replication in chronological order:
1. Primase binds to the site of origin
2. Single stranded primase attach to DNA strands
3. Hydrogen bonds between base pairs of anti parallel strands are broken
4. DNA polymerase binds to the template strand
5. RNA primer is added - Correct Answers -3,2,1,5,4
Which of the following is incorrectly paired? - Correct Answers -D) sliding clamp
synthesizes DNA
The leading and the lagging strand differ in that ________ - Correct Answers -the
leading strand is synthesized in the same direction as the movement of the replication
fork, and the lagging strand is synthesized in the opposite direction
The epsilon subunit of DNA polymerase III of E. coli has exonuclease activity. How does
it function in the proofreading process? The epsilon subunit_______ - Correct Answers -
removes a mismatched nucleotide
The mutation resulting in sickle cell disease changes one base pair of DNA so that a
codon now codes for a different amino acid, making in an example of a
________________. - Correct Answers -missense mutation
Which of the following mutations would be most likely to have a harmful effect on an
organism? - Correct Answers -a single nucleotide insertion downstream of, and close to,
the start of the coding sequence
Put the following events of bacterial transcription in chronological order.
1. Sigma is released.
2. Sigma binds to RNA polymerase.
3. Sigma binds to the promoter region
4. The double helix of DNA is unwound, breaking hydrogen bonds between
complementary strands
, 5. Transcription begins. - Correct Answers -2,3,4,5,1
What molecules in the splicesome catalyze the intron removal reactions? - Correct
Answers -Ribozymes
5'UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'
Which components of the previous molecule will also be found in mRNA in the cytosol?
- Correct Answers -5' UTR E1 E2 E3 E4 UTR 3'
What ensures that the correct amino acid is added during translation? - Correct
Answers -The anticodon of a properly formed aminoacyl tRNA
How does termination of translation take place? - Correct Answers -a stop codon is
reached
What characteristic of short tandem repeats (STRs) DNA makes it useful for DNA
fingerprinting? - Correct Answers -the number of repeats varies widely from person to
person or animal to animal
A labratory might use dideoxyribnucleotides to __________________. - Correct
Answers -sequence a DNA fragment
What is an example of metagenomics? - Correct Answers -Sequencing DNA from a
group of species from the same ecosystem
Once a peptide bond has been formed between the amino acid attached to the tRNA in
the P site and the amino acid associated with the tRNA in the A site, what occurs next?
- Correct Answers -translocation
Bacterial and eukaryotic cells primarily control gene expression at the level of
transcription. If instead cells exerted control of gene expression primarily at the post-
translation level, what would be different? - Correct Answers -cells would expend
significantly more energy
The greatest expression of the lac operon occurs when lactose levels are
_____________. - Correct Answers -high and glucose levels are low
According to the lac operon model proposed by Jacob and Monod, what is predicted to
occur if the operator is removed from the operon? - Correct Answers -the lac operon
would be transcribed continuously
Why are the genes involved in lactose metabolism considered to be an operon? -
Correct Answers -they are all controlled by the same operator
If you were to observe the activity of methylated DNA, you would expect it to
_______________. - Correct Answers -have turned off or slowed down the process of
transcription
ANSWERS
Suppose you are provided with an actively dividing culture of E. coli bacteria to which
radioactive thymine has been added. What would happen if a cell replicates once in the
presence of this radioactive base? - Correct Answers -DNA in both daughter cells would
be radioactive
Put the following steps of DNA replication in chronological order:
1. Primase binds to the site of origin
2. Single stranded primase attach to DNA strands
3. Hydrogen bonds between base pairs of anti parallel strands are broken
4. DNA polymerase binds to the template strand
5. RNA primer is added - Correct Answers -3,2,1,5,4
Which of the following is incorrectly paired? - Correct Answers -D) sliding clamp
synthesizes DNA
The leading and the lagging strand differ in that ________ - Correct Answers -the
leading strand is synthesized in the same direction as the movement of the replication
fork, and the lagging strand is synthesized in the opposite direction
The epsilon subunit of DNA polymerase III of E. coli has exonuclease activity. How does
it function in the proofreading process? The epsilon subunit_______ - Correct Answers -
removes a mismatched nucleotide
The mutation resulting in sickle cell disease changes one base pair of DNA so that a
codon now codes for a different amino acid, making in an example of a
________________. - Correct Answers -missense mutation
Which of the following mutations would be most likely to have a harmful effect on an
organism? - Correct Answers -a single nucleotide insertion downstream of, and close to,
the start of the coding sequence
Put the following events of bacterial transcription in chronological order.
1. Sigma is released.
2. Sigma binds to RNA polymerase.
3. Sigma binds to the promoter region
4. The double helix of DNA is unwound, breaking hydrogen bonds between
complementary strands
, 5. Transcription begins. - Correct Answers -2,3,4,5,1
What molecules in the splicesome catalyze the intron removal reactions? - Correct
Answers -Ribozymes
5'UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'
Which components of the previous molecule will also be found in mRNA in the cytosol?
- Correct Answers -5' UTR E1 E2 E3 E4 UTR 3'
What ensures that the correct amino acid is added during translation? - Correct
Answers -The anticodon of a properly formed aminoacyl tRNA
How does termination of translation take place? - Correct Answers -a stop codon is
reached
What characteristic of short tandem repeats (STRs) DNA makes it useful for DNA
fingerprinting? - Correct Answers -the number of repeats varies widely from person to
person or animal to animal
A labratory might use dideoxyribnucleotides to __________________. - Correct
Answers -sequence a DNA fragment
What is an example of metagenomics? - Correct Answers -Sequencing DNA from a
group of species from the same ecosystem
Once a peptide bond has been formed between the amino acid attached to the tRNA in
the P site and the amino acid associated with the tRNA in the A site, what occurs next?
- Correct Answers -translocation
Bacterial and eukaryotic cells primarily control gene expression at the level of
transcription. If instead cells exerted control of gene expression primarily at the post-
translation level, what would be different? - Correct Answers -cells would expend
significantly more energy
The greatest expression of the lac operon occurs when lactose levels are
_____________. - Correct Answers -high and glucose levels are low
According to the lac operon model proposed by Jacob and Monod, what is predicted to
occur if the operator is removed from the operon? - Correct Answers -the lac operon
would be transcribed continuously
Why are the genes involved in lactose metabolism considered to be an operon? -
Correct Answers -they are all controlled by the same operator
If you were to observe the activity of methylated DNA, you would expect it to
_______________. - Correct Answers -have turned off or slowed down the process of
transcription
