ETS major field test in Biology
Questions All Solved.
Pyrimidine dimers formed in DNA due to UV radiation can be repaired by?
SOS repair
Double strand break repair
Mismatch repair
Photoreactivation repair (nucleotide excision repair)
Base excision repair - Answer Photoreactivation repair (nucleotide excision repair)
Which of the following repair mechanisms uses methyl groups to distinguish between parental and
daughter strands?
Answers:
Mismatch repair
Photoreactivation repair (Nucleotide excision repair)
SOS repair
Double strand break repair
Base excision repair - Answer Mismatch repair
Which of the following types of molecules is always found in virions?
Answers:
Protein
RNA
Lipid
DNA
Carbohydrate - Answer Protein
,A Barr body found within the female mammalian cell's nucleus is an example of ___
Answers:
Euchromatin
Polytene chromosome
Pseudogenes
Heterochromatin
Cistron - Answer Heterochromatin
In vertebrate genes, transcription regulatory regions that contain CpG islands are inactivated by which
CpG modification?
Answers:
Methylation
Ubiquitination
Acetylation
Phosphorylation
Myristoylation - Answer Methylation
TATA-binding protein (TBP) is a key transcription factor in eukaryotes. A schematic representation of the
240-amino acid TBP of yeast is shown in Fig. 1 below, with the positions of 2 mutations indicated. The
boxed area represents the evolutionarily conserved C-terminal domain of TBP, and the shaded (dark)
regions of this domain represent two repeated elements involved in DNA binding. One mutation (P65S)
changes proline 65 to serine and the other I143N changes isoleucine 143 to asparagine. Fig. 2 below
represents autoradiographs of gels containing RNA transcripts produced in extracts of wild type or
mutant cells. Lanes 1-2 are from wild-type yeast (WT), lanes 3-4 are from the I143N mutant and lanes 5-
6 are from P65S mutant, as indicated. Fig. 2A shows transcripts of a gene transcribed by RNA polymerase
I (Pol I). Fig. 2B shows transcripts of a gene transcribed by RNA polymerase II (Pol II). Fig. 2C shows
transcripts - Answer Whether mutant transcription phenotypes are due to perturbation of TBP
function.
A set of genes from Bacillus subtilis that encode the proteins required for sporulation have conserved
DNA sequences -35 and -10 nucleotides before the site of transcript initiation. However, the sequence at
-35 is different from that seen in most other genes from that species. Which of the following best
explains this difference?
Answers:
,Transcription of these genes is induced by cAMP
Translation of the mRNAs transcribed from these genes requires specific ribosomes that recognize a
modified Shine-Dalgarno sequence
A novel sigma factor is required for transcription initiation at these genes
The -35 sequence is the binding site for a repressor of transcription
The replication of these genes requires a specifically modified DNA polymerase. - Answer A novel sigma
factor is required for transcription initiation at these genes
Which of the following repair mechanisms is often mutagenic?
Answers:
Mismatch repair
Photoreactivation repair (Nucleotide excision repair)
Base excision repair
SOS repair - Answer SOS repair
The polytene chromosomes seen in Drosophila are
Answers:
Multiple copies of a single chromosome
Produced by repeated rounds of DNA replication followed by nuclear division
Produced only after the completion of mitosis
Not carrying out transcription
smooth in appearance - Answer Multiple copies of a single chromosome
A frameshift mutation is created when
Answers:
A codon's nucleotide sequence changes so that it calls for production of a different amino acid than the
original one
An initial mutation is reversed by a second mutation
A codon's nucleotide sequence changes so that instead of coding for a given amino acid, it acts to
terminate translation
, A base pair is either inserted or deleted in a gene
A codon's nucleotide sequence changes but the amino acid it codes for does not change. - Answer A
base pair is either inserted or deleted in a gene
Which of the following best explains how mutations in DNA can result in the expression of a new
phenotype?
Answers:
The polarity of tRNA becomes the opposite of that of DNA
A different polypeptide is produced
Eukaryotes and prokaryotes have similar ribosomes
The gene is now read in the 3' to 5' direction
Nucleic acids are methylated - Answer A different polypeptide is produced
Based on the figure shown, the RNA primer can be found at
Answers:
C
D
E
A
B - Answer A
In genetic engineering, bacteria are commonly used to produce mammalian proteins. In these instances
the cDNA that codes for the protein is used rather than the genomic DNA. Which of the following
provides the best explanation for doing this?
Answers:
It is easier to clone RNA than DNA
It is not possible to clone the entire coding region of the gene
It is easier to clone cDNA than genomic DNA of comparable size
Most eukaryotic genes have introns that cannot be removed in bacteria.
Questions All Solved.
Pyrimidine dimers formed in DNA due to UV radiation can be repaired by?
SOS repair
Double strand break repair
Mismatch repair
Photoreactivation repair (nucleotide excision repair)
Base excision repair - Answer Photoreactivation repair (nucleotide excision repair)
Which of the following repair mechanisms uses methyl groups to distinguish between parental and
daughter strands?
Answers:
Mismatch repair
Photoreactivation repair (Nucleotide excision repair)
SOS repair
Double strand break repair
Base excision repair - Answer Mismatch repair
Which of the following types of molecules is always found in virions?
Answers:
Protein
RNA
Lipid
DNA
Carbohydrate - Answer Protein
,A Barr body found within the female mammalian cell's nucleus is an example of ___
Answers:
Euchromatin
Polytene chromosome
Pseudogenes
Heterochromatin
Cistron - Answer Heterochromatin
In vertebrate genes, transcription regulatory regions that contain CpG islands are inactivated by which
CpG modification?
Answers:
Methylation
Ubiquitination
Acetylation
Phosphorylation
Myristoylation - Answer Methylation
TATA-binding protein (TBP) is a key transcription factor in eukaryotes. A schematic representation of the
240-amino acid TBP of yeast is shown in Fig. 1 below, with the positions of 2 mutations indicated. The
boxed area represents the evolutionarily conserved C-terminal domain of TBP, and the shaded (dark)
regions of this domain represent two repeated elements involved in DNA binding. One mutation (P65S)
changes proline 65 to serine and the other I143N changes isoleucine 143 to asparagine. Fig. 2 below
represents autoradiographs of gels containing RNA transcripts produced in extracts of wild type or
mutant cells. Lanes 1-2 are from wild-type yeast (WT), lanes 3-4 are from the I143N mutant and lanes 5-
6 are from P65S mutant, as indicated. Fig. 2A shows transcripts of a gene transcribed by RNA polymerase
I (Pol I). Fig. 2B shows transcripts of a gene transcribed by RNA polymerase II (Pol II). Fig. 2C shows
transcripts - Answer Whether mutant transcription phenotypes are due to perturbation of TBP
function.
A set of genes from Bacillus subtilis that encode the proteins required for sporulation have conserved
DNA sequences -35 and -10 nucleotides before the site of transcript initiation. However, the sequence at
-35 is different from that seen in most other genes from that species. Which of the following best
explains this difference?
Answers:
,Transcription of these genes is induced by cAMP
Translation of the mRNAs transcribed from these genes requires specific ribosomes that recognize a
modified Shine-Dalgarno sequence
A novel sigma factor is required for transcription initiation at these genes
The -35 sequence is the binding site for a repressor of transcription
The replication of these genes requires a specifically modified DNA polymerase. - Answer A novel sigma
factor is required for transcription initiation at these genes
Which of the following repair mechanisms is often mutagenic?
Answers:
Mismatch repair
Photoreactivation repair (Nucleotide excision repair)
Base excision repair
SOS repair - Answer SOS repair
The polytene chromosomes seen in Drosophila are
Answers:
Multiple copies of a single chromosome
Produced by repeated rounds of DNA replication followed by nuclear division
Produced only after the completion of mitosis
Not carrying out transcription
smooth in appearance - Answer Multiple copies of a single chromosome
A frameshift mutation is created when
Answers:
A codon's nucleotide sequence changes so that it calls for production of a different amino acid than the
original one
An initial mutation is reversed by a second mutation
A codon's nucleotide sequence changes so that instead of coding for a given amino acid, it acts to
terminate translation
, A base pair is either inserted or deleted in a gene
A codon's nucleotide sequence changes but the amino acid it codes for does not change. - Answer A
base pair is either inserted or deleted in a gene
Which of the following best explains how mutations in DNA can result in the expression of a new
phenotype?
Answers:
The polarity of tRNA becomes the opposite of that of DNA
A different polypeptide is produced
Eukaryotes and prokaryotes have similar ribosomes
The gene is now read in the 3' to 5' direction
Nucleic acids are methylated - Answer A different polypeptide is produced
Based on the figure shown, the RNA primer can be found at
Answers:
C
D
E
A
B - Answer A
In genetic engineering, bacteria are commonly used to produce mammalian proteins. In these instances
the cDNA that codes for the protein is used rather than the genomic DNA. Which of the following
provides the best explanation for doing this?
Answers:
It is easier to clone RNA than DNA
It is not possible to clone the entire coding region of the gene
It is easier to clone cDNA than genomic DNA of comparable size
Most eukaryotic genes have introns that cannot be removed in bacteria.
