TrmB protein can bind to the promoter region of malE gene, and trehalose can bind to TrmB protein. In the presence of trehalose, the binding of TrmB protein to malE gene was inhibited, leading to the transcription of malE gene. So we can know that TrmB protein is a ()
A. Inducer
B. Positive control protein
C. Operon
D. Repressor
E. Repressor gene
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Here is a mRNA of prokaryote. 5'-GGCGAACAUGGAGGCTAGAUGCACCCUUCGCAGUACGU-3'. The codons to be translated can be().
A. -AUG-ACG-CUU-CCC-ACG-UAG-CTA-
B. -AUG-GAG-GCT-AGA-UGC-ACC-CUU-CGC-AGU-ACG-
C. -AUG-UUC-GCC-
D. -CTA-GAU-GCA-CCC-UUC-GCA-GUA-CGU-
E. -AUG-CAC-CCU-UCG-CAG-UAC-
The content of which chemical element is usually constant in a nucleic acid: ____
A. C
B. O
C. N
D. H
E. P
Two important experiments to prove that DNA is genetic material are: virulence transformation experiment of Diplococcus pneumoniaand infection experiment of T2 phage to E. coli. The key point of these two experiments is:
A. DNA isolated from infected organisms can be used as pathogenic agents.
B. It is DNA mutation that cause the loss of virulence.
C. Foreign DNA (not protein) absorbed by organisms changed genetic potency.
DNA cannot be transferred between different organisms, so it must be a very conservative molecule.
E. DNA of eukaryotes, prokaryotes and virus can be mixed and replaced with each other.
A gene is the DNA sequences encoding a protein():( )