Download 分子生物學 考題 – 林富邦老師部份

分子生物學 考題 – 林富邦老師部份
一 單選題 (每題 2 分 共 18 分)
1. When the cellular level of tryptophan decreases in E. coli:
A. tryptophan-bound Trp repressor associates with trp operator.
B. Trp aporepressor has lowered affinity for trp promoter allowing RNA.
polymerase binding and transcription of the trp operon.
C. tryptophan binds trp inducer to promote positive control of trp promoter.
D. trp repressor has a greater affinity for trp operator.
E. none of the above.
2. How many high-energy phosphoric anhydride bonds per amino acid for the energy
expenditure for protein synthesis
A. 0
B. 1
C. 2
D. 3
E. 4
3. Termination of translation in prokaryotic cells requires:
A. binding of the terminator tRNA to the termination codon.
B. interaction of release factors with the termination codon.
C. ternary interaction of the release factor and the termination tRNA with the
termination codon.
D. release factor interaction with the Shine-Dalgarno sequence and
subsequent dissociation of the two ribosomal subunits.
E. displacement of EF-G by EF-Tu:aminoacyl-tRNA
4. Eukaryotic secretory proteins are synthesized and translocated via the endoplasmic
reticulum. Order the following sequence of events for this process.
A. signal sequence removed.
B. glycosylation in the ER lumen.
C. signal sequence synthesis on ribosomes.
D. SRP binds signal sequence and subsequently binds SRP-receptor.
E. ribosome dissociates.
A. A, C, E, B, D
B. C, D, A, B, E
C. C, A, D, B, E
D. A, C, B, D, E
E. C, B, D, E, A
5. Translation of a synthetic polyribonucleotide containing the repeating sequence
CAA in a cell-free protein-synthesizing system produced three homopolypeptides:
polyglutamine, polyasparagine, and polythreonine. If the codons for glutamine and
asparagine are CAA and AAC, respectively, which of the following triplets is a codon
for threonine?
A. ACC
B. CAA C. CAC
D. CCA E. ACA
6. Cyclic AMP regulates the lac operon by
A.
B.
C.
binding to the operator to turn on transcription
binding to the lac repressor to prevent transcription
combining with the catabolite activator protein (CAP) to from a complex,
which turns on transcription by binding to the promoter
D. combining with the catabolite activator protein to remove the latter's
inhibition of transcription
E. none of the above
7. DNA contains sequences of bases known as promoters which
A. are recongnized by the core enzyme of RNA polymerase
B. occur in the chain just before the message sequence that defines the message
RNA (mRNA)
C. are single-stranded regions of the duplex DNA
D. are transcribed into RNA sequences
E. are not functional in prokaryotes
8. Which of the following mutations would be most likely to have a harmful effect on
an organism?
A. a base-pair substitution
B. a deletion of three nucleotides near the middle of a gene
C. a single nucleotide deletion in the middle of an intron
D. a single nucleotide deletion near the end of the coding
E. a single nucleotide insertion downstream of, and close to, the start of the
coding sequence
9. The appropriate order for the basic steps of protein synthesis are:
A. The elongation reaction transfers the peptide chain from the peptidyl-tRNA in the P
site to the aminoacyl-tRNA in the A site.
B. The P site is occupied by peptidyl-tRNA carrying the growing polypeptide chain.
C. Binding of mRNA by the small subunit followed by association of a particular
initiator aminoacyl-tRNA that recognizes the first codon.
D. The large ribosomal subunit joins the initiation complex, preparing it for the
elongation stage.
E. The new, longer peptidyl-tRNA moves from the A site into the P site as the ribosome
moves one codon further along the mRNA.
A. A, C, E, B, D
B. B, E, C, D, A
C. C, D, A, B, E
D. D, C, E, B, A
E. C, D, B, A, E
二 複選題 (每題 3 分 共 15 分)
1. Characteristics of control mechanisms that regulate transcription in prokaryotes
are:
A. protein : protein interactions are an essential component of transcription
regulation.
B. DNA : protein interactions are central to transcription regulation.
C. regulatory proteins commonly bind DNA at sites of at least partial dyad
symmetry or inverted repeats.
D. regulatory proteins receive cues that signal the status of the environment of
the cell.
E. None of the above.
2. The genetic code has the following characteristics:
A. It is degenerate.
B. It is read 3' to 5'.
C. It is read from a fixed starting point without punctuation.
D. It is not overlapping.
E. A group of three bases codes for one amino acid
3. The correct statements about the tRNA molecule with the anticodon 5'CAU are:
A. It is the anticodon for tRNAfmet.
B. The wobble base in the anticodon would be cytosine.
C. Its anticodon can theoretically base pair with up to three different codons.
D. Its anticodon can base pair to the codon 5'AUG.
E. All are correct.
4. GTP hydrolysis is essential for the following:
A. the formation of the initiation complex (translationally active 70 S
ribosome complex).
B. the elongation step of translation.
C. the translocation step of translation.
D. the binding of release factors to the ribosome.
E. all utilize GTP hydrolysis
5. Proteolytic cleavages have been shown to be involved in the following processes:
A. inactivation of lacI repressor.
B. elimination of the N-terminal Met residue.
C. activation of zymogens.
D. elimination of signal sequences after the protein has reached its proper
location.
E. digestion of dietary proteins.