Chapter 7 - Membrane Structure

Question 0

Having both a hydrophilic and hydrophobic region

Answer 0

Amphipathic

Question 1

The plasma allows some substances to cross it more easily than others

Answer 1

Selective permeability

Question 2

Currently accepted model of the cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

Answer 2

Fluid mosaic model

Question 3

Proteins that penetrate the hydrophobic interior of the lipid bilayer; majority are transmembrane proteins

Answer 3

Integral proteins

Question 4

Proteins not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane often to expose parts of integral proteins

Answer 4

Peripheral proteins

Question 5

Short, branched chains of carbohydrates covalently bonded to lipids

Answer 5

Glycolipids

Question 6

Short, branched chains of carbohydrates covalently bound to proteins

Answer 6

Glycoproteins

Question 7

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane

Answer 7

Transport proteins

Question 8

Channel protein that facilitates the passage of water molecules through the membrane in certain cells; allows up to 3 billion water molecules per second

Answer 8

Aqua poring

Question 9

Movement of particles of any substance so that they spread out into the available space

Answer 9

Diffusion

Question 10

Region along which the density of a chemical substance increases or decreases

Answer 10

Concentration gradient

Question 11

Diffusion of free water across a selectively permeable membrane whether artificial or cellular

Answer 11

Osmosis

Question 12

The ability of a surrounding solution to cause a cell to gain or lose water

Answer 12

Tonicity

Question 13

No net movement of water across the cell membrane; equal solutes

Answer 13

Isotonic

Question 14

Solution causing a cell to lose water due to higher concentration of solutes outside the cell

Answer 14

Hypertonic

Question 15

Solutions causing cell to take up water due to lower concentration of solutes outside the cell

Answer 15

Hypotonic

Question 16

Control of solute concentrations and water balance

Answer 16

Osmoregulation

Question 17

very firm; healthy state for most plants (hypotonic)

Answer 17

Turgid

Question 18

Limp; no net tendency for water to enter the plant cell (isotonic)

Answer 18

Flaccid

Question 19

Process causing a plant to wilt and can lead to death; caused by hypertonic conditions

Answer 19

Plasmolysis

Question 20

Polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane

Answer 20

Facilitated diffusion

Question 21

Channel proteins that transport ions

Answer 21

Ion channels

Question 22

Ion channels that open or close in response to stimulus

Answer 22

Gated channels

Question 23

Movement of a solute across a membrane against its gradient requiring the expenditure of energy

Answer 23

Active transport

Question 24

Transport system which exchanges Na+ for K+ across the plasma membrane of animal cells

Answer 24

Sodium-potassium pump

Question 25

Voltage across a membrane ranging from about -50 to -200 millivolts

Answer 25

Membrane potential

Question 26

Combination of forces acting on an ion; these forces are a chemical force (the ion’s concentration gradient) and an electrical force (the effect of the membrane potential on the ion’s movement)

Answer 26

Electrochemical gradient

Question 27

Transport protein that generates voltage across a membrane

Answer 27

Electrogenic pump

Question 28

Main electrogenic pump of plants, fungi, and bacteria which actively transports protons (H+) out of the cell transferring positive charge from the cytoplasm to the extra cellular solution

Answer 28

Proton pump

Question 29

Mechanism when a transport protein can couple the “downhill” diffusion of the solute to the “uphill” transport of a second substance against its own concentration gradient

Answer 29

Cotransport

Question 30

Cell secretion of certain molecules by the fusion of vesicles with the plasma membrane

Answer 30

Exocytosis

Question 31

Cell intake of molecules and particulate matter by forming new vesicles from the plasma membrane

Answer 31

Endocytosis

Question 32

Any molecule that binds specifically to a receptor site on another molecule

Answer 32

Ligands

Question 33

Cell engulfs a particle by extending pseudopodia around it and packaging it within a food vacuole; the particle is digested after the vacuole fuses with a lysosome

Answer 33

Phagocytosis

Question 34

Cell gulps droplets of extra cellular fluid into tiny vesicles

Answer 34

Pinocytosis

Question 35

Specialized type of pinocytosis that enables the cell to acquire bulk quantities of specific substances even though those may not be concentrated in the extra cellular fluid

Answer 35

Receptor-mediated endocytosis