Chapter Five - Membranes and Transport

Question 1

Plasma (Cell) Membrane

Answer 1

The outer limit of the cytoplasm responsible for the regulation of substances moving into and out of cells.

Question 2

Fluid Mosaic Model

Answer 2

Model proposing that the membrane consists of a fluid phospholipid bilayer in which proteins are embedded and float freely.

Question 3

Membrane Asymmetry

Answer 3

Particles on either side of the membrane differ in size, number, and shape, providing evidence that the two sides are distinctly different.

Question 4

Phospholipid

Answer 4

A phosphate-containing lipid.

Question 5

Amphipathic Bilayer

Answer 5

Contains a region that is hydrophobic and a region that is hydrophilic.

Question 6

Hydrophobic

Answer 6

Non polar substances that are excluded by water and other polar molecules.

Question 7

Hydrophilic

Answer 7

Polar molecules that associate readily with water.

Question 8

Micelle

Answer 8

A sphere composed of a single layer of lipid molecules.

Question 9

Membrane Fluidity

Answer 9

Fluidity of the lipid bilayer is dependent on how densely the individual lipid molecules can pack together influenced by two factors.

1. Composition of lipid molecules.
2. Temperature.

Question 10

Saturated Fatty Acids

Answer 10

Fatty acid with only single bonds linking the carbon atoms.

Question 11

Unsaturated Fatty Acids

Answer 11

Fatty acid with one or more double bonds linking the carbons.

Question 12

Desaturases

Answer 12

A group of enzymes that synthesize unsaturated fatty acids.

Question 13

Cholesterol

Answer 13

The predominant sterol of animal cell membranes.

Question 14

Integral Membrane Proteins

Answer 14

Protein embedded in a phospholipid bilayer.

Question 15

Peripheral Membrane Proteins

Answer 15

Protein held to membrane surfaces by noncovalent bonds formed with the polar parts of integral membrane proteins or membrane lipids.

Question 16

Passive transport

Answer 16

The transport of substances across cell membranes without expenditure of energy, as in diffusion.

Question 17

Diffusion

Answer 17

The net movement of ions or molecules from a region of higher concentration to a region of lower concentration.

Question 18

Facilitated Diffusion

Answer 18

Mechanism by which polar and charged molecules diffuse across membranes with the help of transport proteins.

Question 19

Carrier Proteins

Answer 19

Transport protein that binds a specific single solute and transports it across the lipid bilayer.

Question 20

Analogous

Answer 20

Performing same function but different evolutionary origin.

Question 21

Osmosis

Answer 21

The passive transport of water across a selectively permeable membrane in response to solute concentration gradients, a pressure gradients, or both.

Question 22

Aquaporins

Answer 22

A specialized protein channel that facilitates diffusion of water through cell membranes.

Question 23

Simple Diffusion

Answer 23

Mechanism by which certain small substances diffuse through the lipid part of biological membrane.