Ch. 5

Question 1

What are the key ingredients of the plasma membrane?

Answer 1

phospholipids

Question 2

What are amphipathic molecules?

Answer 2

contain both a hydrophillic region and a hydrophobic region

Question 3

What is the Fluid Mosaic Model?

Answer 3

envisions the membrane as a “mosaic” of proteins drifting laterally in a fluid phospholipid bulayer

the currently accepted model of cell membrane structure

Question 4

What are the functions of membrane proteins?

Answer 4

1. transport
2. signaling
3. enzymes

Question 5

What is selective permeability?

Answer 5

a property of biological membranes that allows them to regulate the passage of substances across them

Question 6

What cannot easily pass through the cell membrane?

Answer 6

large molcules, polar molecules, ions

they require the help of membrane proteins!

Question 7

What are transport proteins?

Answer 7

proteins embedded in the membrane that help certain substances cross it

Question 8

What is an aquaporin?

Answer 8

a channel protein in the cell membrane that specifically facilitates osmosis

Question 9

What is diffusion?

Answer 9

the movement of substances from an area of high concentration to an area of low concentration

will continue to move down the gradient until equilibrium is reached

Question 10

What is passive transport?

Answer 10

the diffusion of a substance across a biological membrane with no energy expenditure

Question 11

What is osmosis?

Answer 11

the diffusion of water across a cell membrane

Question 12

What is tonicity?

Answer 12

the ability of a solution surrounding a cell to cause that cell to either gain or lose water

Question 13

What is a hypotonic solution?

Answer 13

having a lower concentration of solute than another solution

causes a cell to take up water

lyse

Question 14

What is a hypertonic solution?

Answer 14

having a higher concentration of solute than another solution

causes a cell to lose water

shrivel

Question 15

What is an isotonic solution?

Answer 15

having the same solute concentration as another solution

causes no net movement of water

Question 16

What is facilitated diffusion?

Answer 16

the passage of molecules across a membrane with the help of membrane proteins

requires no energy expenditure

Question 17

What is active transport?

Answer 17

the movement of a substance across a membrane mediated by specific transport proteins

requires an expenditure of energy

Question 18

What is membrane potential?

Answer 18

the voltage across a cell’s membrane, affects the activity of excitable cells and transmembrane movement

Question 19

What are ion pumps?

Answer 19

carrier proteins that carry cations and anions across a cell membrane

influece action potential

Question 20

What is cotransport?

Answer 20

occurs when active transport of a solute indirectly drives transport of other substances

Question 21

What is exocytosis?

Answer 21

the release of substances out of a cell by the fusion of a vesicle with the membrane

Question 22

What is endocytosis?

Answer 22

a process in which a cell engulfs extracellular material through an inward folding of its plasma membrane

Question 23

What are the 3 types of endocytosis?

Answer 23

1. phagocytosis
2. pinocytosis
3. receptor-mediated

Question 24

What is phagocytosis?

Answer 24

a cell engulfs large particles or whole cells

cell eating

Question 25

What is pinocytosis?

Answer 25

a cell ingests extracellular fluid and its dissolved solutes

cell drinking

Question 26

What is receptor-mediated endocytosis?

Answer 26

the uptake of specific molecules based on a cell’s receptor proteins

enables cell to acquire bulk quantities of a substance

Question 27

What are the 3 stages of cell signaling?

Answer 27

1. reception
2. transduction
3. response

Question 28

What is reception?

Answer 28

the binding of a signaling molecule to a receptor protein, activating the receptor by causing it to change shape

Question 29

What is transduction?

Answer 29

the binding of the signaling molecule alters the receptor and initiates a signal transduction pathway

occurs in a series of steps

Question 30

What is reception?

Answer 30

the change in a specific cellular activity brought about by a transduced signal from outside the cell

Question 31

What is a signal transduction pathway?

Answer 31

a series of steps linking a mechanical, chemical, or electrical stimulus to a specific cellular response