Actin Filaments Have Polarity

question 60

Multiple Choice

Actin filaments have polarity. This means that the two ends can be identified due to structural differences. The plus end is the end to which subunits are added more rapidly, or the end of polymerization. Which of the following would enable you to identify the plus end of actin filaments?

• A) adding radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization
• B) adding radiolabeled actin subunits to a mixture of actin filaments in which conditions favor depolymerization
• C) determining the ionic charge of the ends of the actin filaments

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Definitions:

Continental Crust

The thick, buoyant part of the Earth's crust that forms the continents; it is generally older and more complex than oceanic crust.

Granite

A common and widely occurring type of intrusive, felsic, igneous rock, characterized by its granular texture.

Abundant Elements

Chemical elements that occur in large quantities in Earth's crust, atmosphere, or oceans, such as oxygen, silicon, and aluminum.

Calcium Carbonate

A chemical compound with the formula CaCO3, commonly found in rocks as the minerals calcite and aragonite and is the main component of pearls, the shells of marine organisms, snails, and eggs.