Biology 1306: Chapter 6 Lipids, Membranes, and the First Cells

Cooking oil and gasoline (A hydrogen) are NOT amphipathic molecules because they?

*Do Not* have a Polar or Charged region.

Diffusion: Water moves quickly across lipid bilayers?

False

What is true of osmosis?

In osmosis, Water moves across a membrane from areas of *LOWER* solute concentration to areas of *HIGHER* solute concentration.

Which aspect of phospholipids is most important to the formation of bilayers?

They are Amphipathic

A phospholipid is a

*Non-Polar* lipid molecule that is made amphipathic by the addition of a phosphate.

Lipids that form membranes have what kind of structure?

*Polar Heads* and *Non-Polar* tails. The polar heads interact with water.

Which of the following crosses lipid bilayers the *fastest*?

A *small*, Non-Polar molecule like Oxygen O2

Which of the following crosses lipid bilayers the SLOWEST?

A sodium ion

Which of the following allows water to move much faster across cell membranes?

Aquaporins

Fatty Acids

Are Insoluble in Water

Fats are considered to be lipids because they?

Are made of *fatty acids*

Phospholipids and Triglycerides both

Have a *Glycerol Backbone*.

Which of the following increases the strength of the hydrophobic interactions in lipid bilayers and thus makes them LESS permeable to polar molecules.

Increasing length of a hydrocarbon chains.

Passive transport occurs when substances diffuse across a membrane in the absence of an outside source?

True

The Fluid-Mosaic model of membrane structure suggests that some proteins are inserted into the lipid bilayer, thus making the membrane a fluid, dynamic mosaic of phospholipids and proteins?

True