Video segment. Assistance may be required. Watch the following video and then answer the questions below.

Source: Meth and Depression (Dopamine), mappsd, YouTube

According to the video, how did the chronic use of methamphetamine affect the person's dopamine?

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She had a hard time experiencing any type of pleasure because the chronic use of methamphetamine had depleted the dopamine stored in her brain. Close Pop Up

Why is this?

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Neurons have a hard time discriminating between the dopamine and the methamphetamine because they are chemically almost identical. Close Pop Up

The following images show a structure of methamphetamine and the chemical messenger dopamine.

Interactive exercise. Assistance may be required. Can you point out the similarities in the two structures? Click on each of the structures to see how they are similar.

The structure and shape of a molecule is extremely important. It determines the molecule’s properties and how it behaves. The shape also determines how the molecule will react under certain conditions.

In previous lessons, you looked at the structure and shape of molecules as flat two-dimensional representations. In reality molecules are not two-dimensional but, in fact, three-dimensional.

Ionic molecules form a specific shape. They have a crystal lattice structure, as seen below, because of the charged nature of the compounds formed during ionic bonding. In this particular compound, each chlorine anion is surrounded by six sodium ions, and six chlorine atoms surround each of those six sodium ions.

The shapes of covalent molecules are more complicated. In the next section, you will learn how to determine the 3-D shape of molecules created by covalent bonds.