Chapter 5 - Plasma Membrane and Function

Question 0

Adhesion Junction

Answer 0

Junction between cells in which the adjacent plasma membranes do not touch but are held together by intercellular filaments attached to buttonlike thickenings.

Question 1

Active Transport

Answer 1

Use of plasma membrane carrier protein to move a molecule or ion from a region of lower concentration to one of higher concentration; it opposes equilibrium and requires energy.

Question 2

Aquaporin

Answer 2

Channel protein through which water can diffuse across a membrane.

Question 3

Bulk Transport

Answer 3

Movement of substances, usually large particles, across the plasma membrane using vesicles.

Question 4

Carrier Protein

Answer 4

Protein in the plasma membrane that combines with and transports a molecule or ion across the plasma membrane.

Question 5

Cell recognition protein

Answer 5

Glycoproteins in the plasma membrane that identify self and help the body defend itself against pathogens.

Question 6

Channel protein

Answer 6

Protein that forms a channel to allow a particular molecule or ion to cross the plasma membrane.

Question 7

Cholesterol

Answer 7

A steroid found in the plasma membrane of animal cells and from which other types of steroids are derived.

Question 8

Concentration gradient

Answer 8

Gradual change in chemical concentration between two areas of differing concentrations.

Question 9

Crenation

Answer 9

In animals cells, shriveling of the cell due to water leaving the cell when the environment is hypertonic.

Question 10

Desmosome

Answer 10

Intercellular junctions that connect cytoskeletons of adjacent cells.

Question 11

Diffusion

Answer 11

Movement of molecules or ions from a region of higher to lower concentration; it requires no energy and tends to lead to an equal distribution (equilibrium).

Question 12

Endocytosis

Answer 12

Process by which substances are moved into the cell from the environment; includes phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Question 13

Exocytosis

Answer 13

Process in which an intracellular vesicle fuses with the plasma membrane so that the vesicle’s contents are released outside the cell.

Question 14

Extracellular matrix (ECM)

Answer 14

Nonliving substance secreted by some animal cells; is composed of protein and polysaccharides.

Question 15

Facilitated transport

Answer 15

Passive transfer of a substance into or out of a cell along a concentration gradient by a process that requires a protein carrier.

Question 16

Fluid mosaic model

Answer 16

Model for the plasma membrane based on the changing location and pattern of protein molecules in a fluid phospholipid bilayer.

Question 17

Gap junction

Answer 17

Junction between cells formed by the joining of two adjacent plasma membranes; it lends strength and allows ions, sugars, and small molecules to pass between cells.

Question 18

Glycolipid

Answer 18

Lipid in plasma membranes that contains an attached carbohydrate chain; assembled in Golgi apparatus.

Question 19

Glycoprotein

Answer 19

Protein in plasma membranes that has an attached carbohydrate chain; assembled in the Golgi apparatus.

Question 20

Hypertonic solution

Answer 20

Higher solute concentration (less water) than the cytoplasma of a cell; causes cell to lose water by osmosis.

Question 21

Hypotonic solution

Answer 21

Solution that contains a lower solute (more water) concentration than the cytoplasm of a cell; causes cell to gain water by osmosis.

Question 22

Isotonic solution

Answer 22

Solution that is equal in solute concentration to that of the cytoplasm of a cell; causes cell to neither lose nor gain water by osmosis.

Question 23

Junction protein

Answer 23

Proteins in the cell membrane that assist in cell-to-cell communication.

Question 24

Osmosis

Answer 24

Diffusion of water through a selectively permeable membrane.

Question 25

Osmotic pressure

Answer 25

Measure of the tendency of water to move across a selectively permeable membrane; visible as an increase in liquid on the side of the membrane with higher solute concentration.

Question 26

Phagocytosis

Answer 26

Process by which cells engulf large substances, forming an intracellular vacuole.

Question 27

Pinocytosis

Answer 27

Process by which vesicle formation brings macromolecules into the cell.

Question 28

Plasmodesmata

Answer 28

In plants, cytoplasmic connections in the cell wall that connect two adjacent cells.

Question 29

Plasmolysis

Answer 29

Contraction of the cell contents due to loss of water.

Question 30

Receptor-mediated endocytosis

Answer 30

Selective uptake of molecules into a cell by vacuole formation after they bind to specific receptor proteins in the plasma membrane.

Question 31

Selectively permeable

Answer 31

Property of the plasma membrane that allows some substances to pass, but prohibits the movement of others.

Question 32

Sodium-potassium pump

Answer 32

Carrier protein in the plasma membrane that moves sodium ions out of and potassium ions into cells; important in the function of nerve and muscle cells in animals.

Question 33

Tight junction

Answer 33

Junction between cells when adjacent plasma membrane proteins joins to form an impermeable barrier.

Question 34

Tonicity

Answer 34

The solute concentration (osmolarity) of a solution compared to that of a cell. If the solution is isotonic to the cell, there is no net movement of water; if the solution is hypotonic, the cell gains water; and if the solution is hypertonic, the cell loses water.

Question 35

Turgor pressure

Answer 35

Pressure of a cell contents against the cell wall; in plant cells, determined by the water content of the vacuole; provides internal support.

Question 36

Receptor protein

Answer 36

Proteins located in the plasma membrane or within the cell; bind to a substance that alters se metabolic aspect of the cell.