The Structure Of Function Of The Plasma Membrane -

Question 1

allows specialized activities to proceed without external interference and enables cellular activities to be regulated
independently of one another.

Answer 1

Compartmentalization

Question 2

also, a distinct compartment. For reactants floating around in solution, their interactions are dependent on random collisions.

Answer 2

Scaffold for biochemical activities.

Question 3

Membranes prevent the unrestricted exchange of molecules from one side to the other. At the same time, membranes provide the means of communication between the compartments they separate.

Answer 3

Providing a selectively permeable barrier

Question 4

physically transporting substances from one side of the membrane to another, often from a region where the solute is present at low concentration into a region with a much higher concentration. The membrane’s transport Machinery allows a cell to accumulate substances, such as sugars and
amino acids the plasma membrane is also able to transport specific ions, thereby establishing ionic gradients across itself.

Answer 4

Transporting solutes

Question 5

The interaction of a plasma membrane receptor with an external stimulus may cause the membrane to generate a signal that stimulates or inhibits internal activities

Answer 5

Responding to external stimuli

Question 6

knew that nonpolar solutes dissolved more
readily in nonpolar solvents than in polar solvents, and those polar solutes had the opposite solubility.

He discovered that the more lipid‐soluble the solute, the more rapidly it would enter
the root hair cells

Answer 6

Ernst Overton

Question 7

type of energy is converted to another
type (energy transduction). The most fundamental energy transduction occurs during photosynthesis when the energy in sunlight is absorbed by membrane‐bound pigments, converted into chemical energy, and stored in carbohydrates.

Answer 7

Energy transduction

Question 7

mediates the interactions between a cell and its neighbors. The plasma membrane allows cells to recognize and signal one another, to adhere when appropriate, and to exchange materials and information.

Answer 7

Intercellular interaction.

Question 8

the core of a membrane contains a bimolecular layer of phospholipids oriented with their water‐soluble head groups facing the outer surfaces and their hydrophobic fatty acid tails facing the interior. cellular membranes might contain a lipid bilayer was made in 1925 by two Dutch scientists.

Answer 8

Gorter and Grendel

Question 9

that is, they contain both hydrophilic and hydrophobic regions

Answer 9

amphipathic

Question 10

What are the three main types of membrane lipids?

Answer 10

phosphoglycerides, sphingolipids, and cholesterol.

Question 11

is virtually absent in
most membranes

Answer 11

phosphatidic acid

Question 12

A less abundant class of membrane lipids,
called sphingolipids,

Answer 12

SPHINGOLIPIDS

Question 12

phosphoglycerides have an
additional group linked to the phosphate, most commonly either

Answer 12

phosphatidylcholine, PC. phosphatidylethanolamine, PE
phosphatidylserine, PS
phosphatidylinositol, PI).

Question 13

is the only phospholipid of the
membrane that is not built with a glycerol backbone.

Answer 13

sphingomyelin

Question 14

molecules are oriented with their small hydrophilic hydroxyl group toward the membrane surface and the remainder
of the molecule embedded in the lipid bilayer

Answer 14

Cholesterol

Question 14

If the carbohydrate is a simple sugar, the glycolipid is called

Answer 14

cerebroside

Question 14

if it is a small cluster of sugars that includes sialic acid, the glycolipid is called

Answer 14

ganglioside

Question 15

The lipid bilayer consists of two distinct leaflets that have a distinctly different lipid composition

Answer 15

One line of experiments that has led to
this conclusion takes advantage of the fact that lipid‐digesting enzymes cannot penetrate the plasma membrane and, consequently, are only able to digest lipids that reside in the outer leaflet of the bilayer.

Question 15

the phospholipid molecules assemble spontaneously to form the walls of fluid‐filled
spherical vesicles, called

Answer 15

liposomes