Why do cells have a plasma membrane (to separate proteins from the nucleus, to define the size of the cell, to distinguish plants from animals or to separate inside the cell from its own environment? ) !

The trp operon in e.coli regulates genes that code for enzymes required for synthesis of the repressible operon. when tryptophan is not available amino acid tryptophan. the trp operon is a in the environment, the trp repressor protein activeinactiveregulated. therefore, rna polymerase can bind to the genes to begin transcription.

What initially causes a nerve impulse? release of enzymes out of the neuron movement of chemicals into the dendrites of the neuron pathogens attacking the dendrites of the neuron red blood cells bathing the neuron

When elements that form a mineral dissolve in hot water, they form a mixture called a(n) a)geode b)vein c)evaporation d)crystallization e)magma f)lava g)solution h)gem