Download 100生技所分生考題,林富邦老師部分

100 生技所分生考題,林富邦老師部分
複選題 (注意：全答對才給分，部份答對不給分) 每題 3 分,合計 9 分
1.
What are the correct following statements about amino acid activation
a. the activation step requires the hydrolysis of the terminal phosphate
group of GTP
b. the aminoacyl-tRNA synthetase is specific for a given amino acid
c. there may be more than one kind of tRNA for a given amino acid
d. aminoacyl-tRNA synthetases transfer the amino acid to the A on 3'end of
tRNA via an aminoacyl-AMP intermediate
e.
once an amino acid is attached to a given tRNA the specificty for
recognition of the appropriate codon on mRNA is due entirely to the
tRNA, and not at all to the amino acid
2. Characteristics of control mechanisms that regulate transcription in prokaryotes
are:
a. DNA : protein interactions are central to transcription regulation.
b. protein : protein interactions are an essential component of transcription
regulation.
c. regulatory proteins commonly bind DNA at sites of at least partial dyad
d.
e.
symmetry or inverted repeats.
regulatory proteins might undergo reversible conformational changes.
regulatory proteins receive cues that signal the status of the environment of
the cell.
3. 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.
e.
elimination of signal sequences after the protein has reached its proper
location.
CRP activation by cAMP.
單選題 (每題 2 分 共 16 分)
1. When the cellular level of tryptophan decreases in E. coli:
A. tryptophan-bound Trp repressor associates with trp operator.
B. trp repressor has a greater affinity for trp operator.
C. tryptophan binds trp inducer to promote positive control of trp promoter.
D. Trp aporepressor has lowered affinity for trp promoter allowing RNA.
polymerase binding and transcription of the trp operon.
E. none of the above.
2. How many high-energy phosphoric anhydride bonds per amino acid for the energy
expenditure for protein synthesis
A. 4
B. 3
C. 2
D. 1
E. 0
3. Termination of translation in prokaryotic cells requires:
A. binding of the terminator tRNA to the termination codon.
B. displacement of EF-G by EF-Tu:aminoacyl-tRNA
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. interaction of release factors with the termination codon.
4. 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. ACA
B. CAA C. CAC
D. CCA E. ACC
5. Cyclic AMP regulates the lac operon by
A. binding to the operator to turn on transcription
B. binding to the lac repressor to prevent transcription
C. combining with the catabolite activator protein to remove the latter's
inhibition of transcription
D. combining with the catabolite activator protein (CAP) to from a complex,
which turns on transcription by binding to the promoter
E. none of the above
6. DNA contains sequences of bases known as promoters which
A. are recongnized by the core enzyme of RNA polymerase
B. are not functional in prokaryotes
C. are single-stranded regions of the duplex DNA
D. are transcribed into RNA sequences
E. occur in the chain just before the message sequence that defines the message
RNA (mRNA)
7. 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 insertion downstream of, and close to, the start of the
coding sequence
E. a single nucleotide deletion near the end of the coding
8. 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. C, D, B, A, E
C. C, D, A, B, E
D. D, C, E, B, A
E. B, E, C, D, A