"Housekeeping Genes" in Bacteria Are Commonly Expressed Constitutively, but Not

question 74

Multiple Choice

"Housekeeping genes" in bacteria are commonly expressed constitutively, but not all of these genes are expressed at the same level (the same number of molecules per cell) . The primary mechanism responsible for variations in the level of constitutive enzymes from different genes is that:

• A) all constitutive enzymes are synthesized at the same rate, but are not degraded equally.
• B) their promoters have different affinities for RNA polymerase holoenzyme.
• C) some constitutively expressed genes are more inducible than others.
• D) some constitutively expressed genes are more repressible than others.
• E) the same number of mRNA copies are made from each gene but are translated at different rates.

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Definitions:

Continental Rifts

Areas where the Earth's crust is stretching and splitting apart, leading to the formation of new oceanic crust.

Felsic

Refers to igneous rocks that are rich in silica and light in color, including granite and rhyolite.

Mafic Magma

Refers to a type of magma that is rich in magnesium and iron, characterized by its dark color and low viscosity.

Subduction Zones

Areas where one tectonic plate is being forced down into the mantle by another plate, often associated with volcanic activity and earthquakes.