Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with
the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?A) The repressor protein attaches to the regulator.B) Allolactose binds to the repressor protein.C) Allolactose binds to the regulator gene.D) The repressor protein and allolactose bind to RNA polymerase.E) RNA polymerase attaches to the regulator.
RNA polymerase must bind to the promoter, and the repressor must be inactive. Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source.
The process of muscle contraction requires several steps.
The most famous theory on how the contraction and relaxation of muscles take place is the sliding filament theory.
However, this theory has been refined and one important addition to it is the mechanism by which myosin can pull actin and cause shortening of the sarcomere.
For the movement of myosin, it binds and releases actin and forms cross bridges.
Myosin is subdivided into two regions - S1 and S2. The contraction of the S1 region is what constitutes the power stroke.
An important requirement of the power stroke is the hydrolysis of ATP to release an inorganic phosphate which provides energy for the process.
