ANSC 221 EXAM QUESTIONS WITH
CORRECT ANSWERS
The lac repressor binds to the operator site and prevents RNA polymerase from
transcribing the operon. When ( ) binds to the repressor, a ( ) occurs that prevents the
repressor from binding to the operator site so transcription can proceed.
A. lactose, shift
B. allolactose, conformational change
C. DNA, change
D. methyl group, conformational change
E. ribosome, shift - Answer-b
General transcription factors (GTFs) are needed for ( ) to bind to the core promoter
which is made up of the transcriptional start site and ( )
A. DNA polymerase, the TATA box
B. ribosome, the -10 region
C. RNA polymerase II, the TATA box.
D. TFIID, promoter
E. DNA methylation - Answer-a
Translation requires ( ), ( ), ( ), and many translation factors.
A. DNA polymerase, tRNA synthetase, codons
B. RNA polymerase, DNA polymerase, codons
C. Aminoacyl tRNA synthtases, tRNA, codons
D. mRNA, aminoacyl tRNAs, ribosomes
E. mRNA, DNA polymerase, RNA polymerase - Answer-d
In bacteria, ( ) binds to RNA polymerase and to a promoter, thereby promoting the
initiation of transcription.
A. sigma factor
B. activator
C. silencer
D. chromatin
E. nucleosome - Answer-a
, The enzyme aminoacyl tRNA synthetase attaches the correct amino acid to a tRNA
molecule to create a ( ).
A. linked tRNA
B. charged tRNA
C. amino acid tRNA
D. tRNA amino acid
E. acid tRNA - Answer-b
Ribosomes have three sites, the ( ), ( ), and ( ) sites.
A. control, synthesis, leaving
B. Protein, Amino acid, extension
C. promoter, transcription, replication
D. initiation, elongation, termination
E. exit (E), peptidyl (P), aminoacyl (A) - Answer-e
In DNA replication, the action of DNA helicase during unwinding of DNA generates
additional coiling just ahead of the replication fork. This excessive coiling is alleviated by
another enzyme called ( ).
A. single strand DNA binding protein
B. origin recognition complex
C. topoisomerase
D. RNA polymerase
E. DNA primase - Answer-c
DNA polymerases are incapable of initiating DNA synthesis on a bare template. They
require a different enzyme to synthesize an RNA primer that can then be extended by
the DNA polymerase. This enzyme that primes DNA synthesis by DNA polymerases is
called
( ).
A. DNA ligase
B. DNA primase
C. histonase
D.proteinase
E. integrase - Answer-b
tRNA molecules have a ( ) structure. Two important sites are the ( ), which covalently
binds to an amino acid, and the ( ) which base-pairs with a codon in mRNA.
A. circular, double stranded, semi-codon
B. cloverleaf, 3' single-stranded region, anticodon
C. dumbbell, double-stranded region, semi-codon
D. X-shaped, single-stranded, anticodon
CORRECT ANSWERS
The lac repressor binds to the operator site and prevents RNA polymerase from
transcribing the operon. When ( ) binds to the repressor, a ( ) occurs that prevents the
repressor from binding to the operator site so transcription can proceed.
A. lactose, shift
B. allolactose, conformational change
C. DNA, change
D. methyl group, conformational change
E. ribosome, shift - Answer-b
General transcription factors (GTFs) are needed for ( ) to bind to the core promoter
which is made up of the transcriptional start site and ( )
A. DNA polymerase, the TATA box
B. ribosome, the -10 region
C. RNA polymerase II, the TATA box.
D. TFIID, promoter
E. DNA methylation - Answer-a
Translation requires ( ), ( ), ( ), and many translation factors.
A. DNA polymerase, tRNA synthetase, codons
B. RNA polymerase, DNA polymerase, codons
C. Aminoacyl tRNA synthtases, tRNA, codons
D. mRNA, aminoacyl tRNAs, ribosomes
E. mRNA, DNA polymerase, RNA polymerase - Answer-d
In bacteria, ( ) binds to RNA polymerase and to a promoter, thereby promoting the
initiation of transcription.
A. sigma factor
B. activator
C. silencer
D. chromatin
E. nucleosome - Answer-a
, The enzyme aminoacyl tRNA synthetase attaches the correct amino acid to a tRNA
molecule to create a ( ).
A. linked tRNA
B. charged tRNA
C. amino acid tRNA
D. tRNA amino acid
E. acid tRNA - Answer-b
Ribosomes have three sites, the ( ), ( ), and ( ) sites.
A. control, synthesis, leaving
B. Protein, Amino acid, extension
C. promoter, transcription, replication
D. initiation, elongation, termination
E. exit (E), peptidyl (P), aminoacyl (A) - Answer-e
In DNA replication, the action of DNA helicase during unwinding of DNA generates
additional coiling just ahead of the replication fork. This excessive coiling is alleviated by
another enzyme called ( ).
A. single strand DNA binding protein
B. origin recognition complex
C. topoisomerase
D. RNA polymerase
E. DNA primase - Answer-c
DNA polymerases are incapable of initiating DNA synthesis on a bare template. They
require a different enzyme to synthesize an RNA primer that can then be extended by
the DNA polymerase. This enzyme that primes DNA synthesis by DNA polymerases is
called
( ).
A. DNA ligase
B. DNA primase
C. histonase
D.proteinase
E. integrase - Answer-b
tRNA molecules have a ( ) structure. Two important sites are the ( ), which covalently
binds to an amino acid, and the ( ) which base-pairs with a codon in mRNA.
A. circular, double stranded, semi-codon
B. cloverleaf, 3' single-stranded region, anticodon
C. dumbbell, double-stranded region, semi-codon
D. X-shaped, single-stranded, anticodon
