Which of the following might decrease the transcription of only one specific gene in a bacterial cell?
(a) a decrease in the amount of sigma factor
(b) a decrease in the amount of RNA polymerase
(c) a mutation that introduced a stop codon into the DNA that precedes the gene's coding sequence
(d) a mutation that introduced extensive sequence changes into the DNA that precedes the gene's transcription start site
(d) Such changes would probably destroy the function of the promoter, making RNA polymerase unable to bind to it. Decreasing the amount of sigma factor or RNA polymerase [choices (a) or (b)] would affect the transcription of most of the genes in the cell, not just one specific gene. Introducing a stop codon before the coding sequence [choice (c)] would have no effect on transcription of the gene, because the transcription machinery does not recognize translational stops.
You might also like to view...
A phospholipid molecule has a polar and a nonpolar end. Because of this, water molecules form
A. polar bonds with the nonpolar end of the phospholipid molecule. B. polar bonds with the polar end of the phospholipid molecule. C. hydrogen bonds with the nonpolar end of the phospholipid molecule. D. hydrogen bonds with the polar end of the phospholipid molecule. E. covalent bonds with the nonpolar end of the phospholipid molecule.
The skin infection streptothrichosis is caused by members of the genus ________.
A. Streptomyces B. Streptococcus C. Dermatophilus D. Propionibacterium
A new protein has been described that transports a growth factor across the plasma membrane. This protein is most likely a/an:
A. cytoplasmic protein. B. integral membrane protein. C. peripheral membrane protein, facing the cytoplasmic side. D. peripheral membrane protein, facing outward.
The autonomic subdivision of the vertebrate nervous system would innervate all but which organ?
a. intestinal muscles b. skeletal muscles c. heart d. pancreas e. liver