MasteringBio

Phospholipids vary in the small molecules attached to the phosphate group. The phospholipid show in the figure has a_____ attached to phosphate

Choline Group

The presence of cholesterol in the plasma membranes of some animals

Enables the membrane to stay fluid more easily when cell temperature drops

A phospholipid has a head made up of a glycerol molecule attached to a single____ which is attached to another small molecule

Phosphate Group

Cell membranes are asymmetrical. Which of the following is the most likely explanation?

The two sides of a cell membrane face different environments and carry out different functions

Why are lipids and proteins free to move laterally in membranes?

There are only weak hydrophobic interactions in the interior of the membrane

Mammalian blood contains the equivalent of 0.15M NaCl. Seawater contains the equivalent of 0.45M NaCl what will happen if red blood cells are transferred to seawater?

Water will leave the cells causing them to shrivel and collapse

A protein that spans the phospholipid bilayer one or more times is

a transmembrane protein

In order for a protein to be an integral membrane protein it would have to be

amphipathic with at least one hydrophobic region

Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?

by increasing the percentage of unsaturated phospholipids in the membrane

In a paramecium, cell surface integral membrane proteins are synthesized

by ribosomes bound to the rough ER

The movement of hydrophobic gas, laughing gas into a cell is an example of

diffusion across the lipid bilayer

A phospholipid also has two tails made up of two ____ molecules which consists of a carboxyl group with long hydrocarbon chain attached

fatty acid

Because the phosphate group and its attachments are either charged or polar, the phospholipid head is ____ which means it has an affinity of water

hydrophilic

Because the C-H bonds in the fatty acid tails are relatively nonpolar the phospholipid tails are ___which means they are excluded from water

hydrophobic

What lipids can move across the lipid bilayer of a membrane directly?

lipids, carbon dioxide, oxygen, and water

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

What molecules can not rapidly pass through the plasma membrane

water, glucose, and hydrogen ions